Leaflet and Census TIGERweb


Fig 1 – Sample Leaflet interface to the US Census Bureau’s new TIGERweb WMS service with Bing Maps background

Ref: http://silverlight.onterrasys.com/MapSavvyLeaflet/

US Bureau of the Census – some background

1990 Census
The 1990 Census line data made a revolutionary leap from GBF-DIME format to TIGER, Topologically Integrated Geographic Encoding and Referencing, and also adopted CD-ROM media distribution. In the early 90′s I wrote a few TIGER translation programs for AutoCAD users and users of a popular (now defunct) desktop GIS package called Atlas*GIS. TIGER was useful for its linear data, but was more often used for the boundary polygons that could be tied to Census population demographic data. The line features of the 1990 TIGER were based on the older 1980 GBF-DIME enhanced with USGS 1:100,000 DLG features. GBF DIME was notable for the tell tale zigzag streets in urban areas.

2000 Census
By the mid 90’s Open GIS Consortium (OGC) was actively working on OpenGIS standards. As the internet continued ramping up, OGC released the OpenGIS Web Map Server (WMS) Specification in 2000. Even though Census data releases are a year or so after the actual census, it was several more years before the Census Bureau started investigating alternative WMS services for distributing data. In the meantime boundaries were available for internet and ftp download in ESRI shp and E00 formats. This was convenient, but requires self hosting web solutions.

2010 Census
Ever since the 2000 WMS specification there were hopes for a service distribution of census TIGER/Line. Not until the end of 2011 was this belatedly realized as TIGERweb. But of course by the mid 2000s internet mapping began changing radically with the popularity of Google Maps, GPS, Bing Maps, Open Street Maps, and now ubiquitous mobile devices. The Census Bureau will need to continue evolving to meet the challenges of these rapid changes.

TIGERweb 2011
So why not use the TIGERweb for an experimental look at some more recent web tools? TIGERweb Viewer UI is based on the ESRI Silverlight APIs. Silverlight is a powerful UI technology, but it is destined to be supplanted by html5. As browser market fragmentation and mobile devices force adoption of standards based technologies, proprietary plugins are just not making the transition, at least for public facing web apps.


Fig 2 – TIGERweb Viewer based on ESRI Silverlight API

TIGERweb Viewer seems oddly designed. Rather than the clean, spare look popular today, TIGERweb Viewer seems to be a throwback to an earlier internet. Unusual matrice animations with rotating panels and creepy crawling boundary selectors seem a bit out of place in the modern web. Even though technically possible, and simple to implement in Silverlight, such distractions do nothing to make the UI endearing. After the first blink most users will inevitably recall early internet flashing text and PowerPoint decks filled with animated gifs. Anyone remember the irritation of Clippy?

However, TIGERweb WMS Service is a wide open door for standards based javascript libraries. One of the more elegant available tools is LeafletJS. This is a “lightweight” js map library that works well with jQuery and abstracts away some of the complexity of supporting a fragmenting mobile browser world.

Leaflet is Open Source BSD-licensed with an active contributing community and available on github. It uses newer html5 technologies available in A-grade browsers, but includes fall back for older browsers. It’s nice to have touch events and the geolocation api.

The Leaflet api provides a convenient L.TileLayer.WMS object that transforms a WMS endpoint into a slippy tile map. Performance isn’t as good as a static tile pyramid, but it isn’t bad and simplifies life immensely.

  var censusTracts = new L.TileLayer.WMS("http://tigerweb.geo.census.gov/ArcGIS/services/tigerWMS/MapServer/WMSServer",
  {
    layers: 'Census Tracts',
    format: 'image/png',
    transparent: true,
    attribution: TigerAttribution
  });

Bing Maps
Unlike Google Maps, Microsoft Bing allows licensed access to tile servers. For development, non-profit, and education uses, this is just a matter of registering for a Bing key. Adding a Bing Maps layer with Leaflet is possible using https://gist.github.com/1221998. Once this Leaflet Bing extension javascript is referenced into a page, adding Bing Map styles is simply a matter of adding L.TileLayer.Bing.

var BingAerialWithLabels = new L.TileLayer.Bing(bingkey, "AerialWithLabels",
{
  maxZoom: 21,
  attribution: BingAttribution
});

Fig 3 – Leaflet Census TIGER WMS with Bing Maps Road style

TIGER/Line 2010 accuracy has been upgraded substantially, but you can occasionally see some discrepancies against Bing Aerial.

Fig 4 – Leaflet Census TIGER WMS with Bing Maps Aerial with Labels style

Once all of the WMS and Bing L.TileLayers are instantiated, a new L.Map with the desired L.TileLayer set is declared this way:

            map = new L.Map('mapDiv',
                    {
                        center: new L.LatLng(39.748, -104.981),
                        zoom: 8,
                        layers: [censusStates, censusCounties, censusTracts, censusBlockGrps, censusBlocks]
                    });

Leaflet also provides a simple L.Control.Layers for a user layer control panel:

            var baseMaps = {
                "BingRoads": BingRoad,
                "BingAerial": BingAerial,
                "BingAerialWithLabels": BingAerialWithLabels
            };

            var overlayMaps = {
                "States": censusStates,
                "Counties": censusCounties,
                "Tracts": censusTracts,
                "BlockGroups": censusBlockGrps,
                "Blocks": censusBlocks,
                "Lakes": censusArealHydrography,
                "Rivers Streams": censusLinearHydrography,
                "LocalRoads": censusLocalRoads,
                "SecondaryRoads": censusSecondaryRoads,
                "PrimaryRoads": censusPrimaryRoads,
                "Nexrad": nexrad
            };

            var layersControl = new L.Control.Layers(baseMaps, overlayMaps,
            {
                collapsed: !L.Browser.touch
            });
            map.addControl(layersControl);

Fig 5 – Leaflet L.Control.Layers

TIGERweb WMS GetFeatureInfo is available for queries. For example:

http://tigerweb.geo.census.gov/ArcGIS/services/tigerWMS/MapServer/WMSServer?Service=WMS&Version=1.1.1&Request=GetFeatureInfo&Layers=Counties&SRS=EPSG:4326&BBOX=-122.5,37.75,-122.25,38.0&width=1000&height=1000&QUERY_LAYERS=Counties&INFO_FORMAT=text/xml&X=100&Y=100

<?xml version="1.0"?>
<FeatureInfoResponse xmlns="http://www.esri.com/wms" xmlns:esri_wms="http://www.esri.com/wms">
<FIELDS
  HU100="111214" --HousingUnits
  POP100="252409"
  INTPTLON="-122.7459738"
  INTPTLAT="+38.0518169"
  CENTLON="-122.7485752"
  CENTLAT="+38.0551413"
  STGEOMETRY="Polygon"
  UR="Null"
  STATE="06"
  OID="27590357299439"
  NAME="Marin County"
  BASENAME="Marin"
  MTFCC="G4020"
  METDIV="41884"
  LSADC="06"
  GEOID="06041"
  FUNCSTAT="A"
  CSA="488"
  COUNTY="041"
  COUNTYCC="H1"
  CBSA="41860"
  AREAWATER="797420433"
  AREALAND="1347585521"
  COUNTYNS="00277285"/>
</FeatureInfoResponse>

jQuery makes XMLHttpRequest communication easy, but TIGERweb WMS doesn’t expose an open ClientAccessPolicy.xml, so a self hosted proxy is required.

            $.ajax({
                type: "GET",
                url: getInfoURL,
                dataType: "xml",
                success: GetFeatureInfo
            });

Fig 6 – Leaflet Popup panel with the results of TIGERweb WMS GetFeatureInfo request

Some Caveats

TIGERweb
1) The TIGERweb WMS furnishes images for all the TIGER boundary and line features. However, there doesn’t seem to be a WMS layer for labels like those on the TIGERweb Viewer. There is an undocumented label service that might be useful.

http://tigerweb.geo.census.gov/ArcGIS/rest/services/Labels/MapServer/export

2) WMS GetFeatureInfo requests can provide information from the polygon stack, but the lack of a cross-domain policy file on the TIGERweb WMS server means that a pass through proxy service needs to be hosted on the same server as the Leaflet web app. This proxy service simply provides the same GetFeatureInfo result to the client while avoiding cross-domain issues.

Leaflet
1) Bing javascript
The Bing javascript extension seemed to run into a problem with intersect at this line:
if (zoom = coverage.zoomMin && coverage.bbox.intersects(bounds))

Removing the intersect(bounds) clause seemed to get things working without noticeable problems:
if (zoom = coverage.zoomMin )

2) Leaflet seems to have problems with TileLayer ordering. Bing TileLayers can mask other features if directly added to the map layer set.

3) There are some odd behaviors on Amazon Kindle Fire, possibly due to the Silk web browser’s EC2 caching.

4) Leaflet L.Control.Layers doesn’t work consistently in the mobile browsers I tested. The collapsed layer control icon never opened for iPhone or Kindle Fire. Adding the suggested option collapsed: !L.Browser.touch keeps the layer control open instead of closing when untouched. This wouldn’t be a problem except that mobile devices don’t have the screen space for extra panels.

5) The default attribution for Bing gets quite lengthy, especially when displaying Aerial vendor meta data. Turning this off and deferring to the Bing Maps Logo frees up more screen space which is at a premium on mobile devices.

Summary

Census Bureau’s new TIGERweb is a great step forward for users of TIGER data. Hopefully the momentum will continue forward to include demographic data. SF1 data joined to TIGER polygons would be a more useful service. Adding an OGC WFS service would be the ideal, but WFS always has problems with potentially very large result sets, so I’m not sure this is practical on a public OGC service.

Since the first time I saw Leaflet I’ve been intrigued with its elegance and the potential for abstracting away some of the issues surrounding web apps targeted at mobile and touch clients. In spite of a few minor issues Leaflet is one of the best javascript map apis I’ve used. I believe the issues I ran into are on a bug list and could be resolved by next release.

This bare bones CensusTest project took only a few hours over the weekend to write using Leaflet.

Fig 7 – Lower Manhattan

Extraterrestrial Map Kinections

image

Fig 1 – LRO Color Shaded Relief map of moon – Silverlight 5 XNA with Kinect interface

 

Silverlight 5 was released after a short delay, at the end of last week.
Just prior to exiting stage left, Silverlight, along with all plugins, shares a last aria. The spotlight now shifts abruptly to a new diva, mobile html5. Backstage the enterprise awaits with a bouquet of roses. Their concourse will linger long into the late evening of 2021.

The Last Hurrah?

Kinect devices continue to generate a lot of hacking interest. With the release of an official Microsoft Kinect beta SDK for Windows, things get even more interesting. Unfortunately, Kinect and the web aren’t exactly ideal partners. It’s not that web browsers wouldn’t benefit by moving beyond the venerable mouse/keyboard events. After all, look at the way mobile touch, voice, inertia, gyro, accelerometer, gps . . . have all suddenly become base features in mobile browsing. The reason Kinect isn’t part of the sensor event farmyard may be just a lack of portability and an ‘i’ prefix. Shrinking a Kinect doesn’t work too well as stereoscopic imagery needs a degree of separation in a Newtonian world.

[The promised advent of NearMode (50cm range) offers some tantalizing visions of 3D voxel UIs. Future mobile devices could potentially take advantage of the human body’s bi-lateral symmetry. Simply cut the device in two and mount one half on each shoulder, but that isn’t the state of hardware at present. ]

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Fig 2 – a not so subtle fashion statement OmniTouch

 

For the present, experimenting with Kinect control of a Silverlight web app requires a relatively static configuration and a three-step process: the Kinect out there, beyond the stage lights, and the web app over here, close at hand, with a software piece in the middle. The Kinect SDK, which roughly corresponds to our visual and auditory cortex, amplifies and simplifies a flood of raw sensory input to extract bits of “actionable meaning.” The beta Kinect SDK gives us device drivers and APIs in managed code. However, as these APIs have not been compiled for use with Silverlight runtime, a Silverlight client will by necessity be one step further removed.

Microsoft includes some rich sample code as part of the Kinect SDK download. In addition there are a couple of very helpful blog posts by David Catuhe and a codeplex project, kinect toolbox.

Step 1:

The approach for using Kinect for this experimental map interface is to use the GestureViewer code from Kinect Toolbox to capture some primitive commands arising from sensory input. The command repertoire is minimal including four compass direction swipes, and two circular gestures for zooming, circle clockwise zoom in, and circle counter clockwise zoom out. Voice commands are pretty much a freebie, so I’ve added a few to the mix. Since GestureViewer toolbox includes a learning template based gesture module, you can capture just about any gesture desired. I’m choosing to keep this simple.

Step 2:

Once gesture recognition for these 6 commands is available, step 2 is handing commands off to a Silverlight client. In this project I used a socket service running on a separate thread. As gestures are detected they are pushed out to local port 4530 on a tcp socket service. There are other approaches that may be better with final release of Silverlight 5.

Step 3:

The Silverlight client listens on port 4530, reading command strings that show up. Once read, the command can then be translated into appropriate actions for our Map Controller.

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Fig 3 – Kinect to Silverlight architecture

Full Moon Rising

 

But first, instead of the mundane, let’s look at something a bit extraterrestrial, a more fitting client for such “extraordinary” UI talents. NASA has been very busy collecting large amounts of fascinating data on our nearby planetary neighbors. One data set that was recently released by ASU, stitches together a comprehensive lunar relief map with beautiful color shading. Wow what if the moon really looked like this!

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Fig 4 – ASU LRO Color Shaded Relief map of moon

In addition to our ASU moon USGS has published a set of imagery for Mars, Venus, Mercury, as well as some Saturn and Jupiter moons. Finally, JPL thoughtfully shares a couple of WMS services and some imagery of the other planets:
http://onmars.jpl.nasa.gov/wms.cgi?version=1.1.1&request=GetCapabilities
http://onmoon.jpl.nasa.gov/wms.cgi?version=1.1.1&request=GetCapabilities

This type of data wants to be 3D so I’ve brushed off code from a previous post, NASA Neo 3D XNA, and adapted it for planetary data, minus the population bump map. However, bump maps for depicting terrain relief are still a must have. A useful tool for generating bump or normal imagery from color relief is SSBump Generator v5.3 . The result using this tool is an image that encodes relative elevation of the moon’s surface. This is added to the XNA rendering pipeline to combine a surface texture with the color relief imagery, where it can then be applied to a simplified spherical model.

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Fig 5 – part of normal map from ASU Moon Color Relief imagery

The result is seen in the MoonViewer client with the added benefit of immediate mode GPU rendering that allows smooth rotation and zoom.

The other planets and moons have somewhat less data available, but still benefit from the XNA treatment. Only Earth, Moon, Mars, Ganymede, and Io have data affording bump map relief.

I also added a quick WMS 2D viewer html using OpenLayers against the JPL WMS servers to take a look at lunar landing sites. Default OpenLayers isn’t especially pretty, but it takes less than 20 lines of js to get a zoomable viewer with landing locations. I would have preferred the elegance of Leaflet.js, but EPSG:4326 isn’t supported in L.TileLayer.WMS(). MapProxy promises a way to proxy in the planet data as EPSG:3857 tiles for Leaflet consumption, but OpenLayers offers a simpler path.

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Fig 6 – OpenLayer WMS viewer showing lunar landing sites

Now that the Viewer is in place it’s time to take a test drive. Here is a ClickOnce installer for GestureViewer modified to work with the Silverlight Socket service: http://107.22.247.211/MoonKinect/

Recall that this is a Beta SDK, so in addition to a Kinect prerequisite, there are some additional runtime installs required:

Using the Kinect SDK Beta

Download Kinect SDK Beta 2:
http://www.kinectforwindows.org/download/

Be sure to look at the system requirements and the installation instructions further down the page. This is Beta still, and requires a few pieces. The release SDK is rumored to be available the first part of 2012.

You may have to download some additional software as well as the Kinect SDK:

Finally, we are making use of port 4530 for the Socket Service. It is likely that you will need to open this port in your local firewall.

As you can see this is not exactly user friendly installation, but the reward is seeing Kinect control of a mapping environment. If you are hesitant to go through all of this install trouble, here is a video link that will give you an idea of the results.

YouTube video demonstration of Kinect Gestures

 

Voice commands using the Kinect are very simple to add so this version adds a few.

Here is the listing of available commands:

       public void SocketCommand(string current)
        {
            switch (command)
            {
                    // Kinect voice commands
                case "mercury-on": { MercuryRB.IsChecked = true; break; }
                case "venus-on": { VenusRB.IsChecked = true; break; }
                case "earth-on": { EarthRB.IsChecked = true; break; }
                case "moon-on": { MoonRB.IsChecked = true; break;}
                case "mars-on": { MarsRB.IsChecked = true; break;}
                case "marsrelief-on": { MarsreliefRB.IsChecked = true; break; }
                case "jupiter-on": { JupiterRB.IsChecked = true; break; }
                case "saturn-on": { SaturnRB.IsChecked = true; break; }
                case "uranus-on": { UranusRB.IsChecked = true; break; }
                case "neptune-on": { NeptuneRB.IsChecked = true; break; }
                case "pluto-on": { PlutoRB.IsChecked = true; break; }

                case "callisto-on": { CallistoRB.IsChecked = true; break; }
                case "io-on": { IoRB.IsChecked = true;break;}
                case "europa-on": {EuropaRB.IsChecked = true; break;}
                case "ganymede-on": { GanymedeRB.IsChecked = true; break;}
                case "cassini-on": { CassiniRB.IsChecked = true; break; }
                case "dione-on":  {  DioneRB.IsChecked = true; break; }
                case "enceladus-on": { EnceladusRB.IsChecked = true; break; }
                case "iapetus-on": { IapetusRB.IsChecked = true;  break; }
                case "tethys-on": { TethysRB.IsChecked = true; break; }
                case "moon-2d":
                    {
                        MoonRB.IsChecked = true;
                        Uri uri = Application.Current.Host.Source;
                        System.Windows.Browser.HtmlPage.Window.Navigate(new Uri(uri.Scheme + "://" + uri.DnsSafeHost + ":" + uri.Port + "/MoonViewer/Moon.html"), "_blank");
                        break;
                    }
                case "mars-2d":
                    {
                        MarsRB.IsChecked = true;
                        Uri uri = Application.Current.Host.Source;
                        System.Windows.Browser.HtmlPage.Window.Navigate(new Uri(uri.Scheme + "://" + uri.DnsSafeHost + ":" + uri.Port + "/MoonViewer/Mars.html"), "_blank");
                        break;
                    }
                case "nasaneo":
                    {
                        EarthRB.IsChecked = true;
                        System.Windows.Browser.HtmlPage.Window.Navigate(new Uri("http://107.22.247.211/NASANeo/"), "_blank"); break;
                    }
                case "rotate-east": {
                        RotationSpeedSlider.Value += 1.0;
                        tbMessage.Text = "rotate east";
                        break;
                    }
                case "rotate-west":
                    {
                        RotationSpeedSlider.Value -= 1.0;
                        tbMessage.Text = "rotate west";
                        break;
                    }
                case "rotate-off":
                    {
                        RotationSpeedSlider.Value = 0.0;
                        tbMessage.Text = "rotate off";
                        break;
                    }
                case "reset":
                    {
                        RotationSpeedSlider.Value = 0.0;
                        orbitX = 0;
                        orbitY = 0;
                        tbMessage.Text = "reset view";
                        break;
                    }

                //Kinect Swipe algorithmic commands
                case "swipetoleft":
                    {
                        orbitY += Microsoft.Xna.Framework.MathHelper.ToRadians(15);
                        tbMessage.Text = "orbit left";
                        break;
                    }
                case "swipetoright":
                    {
                        orbitY -= Microsoft.Xna.Framework.MathHelper.ToRadians(15);
                        tbMessage.Text = "orbit right";
                        break;
                    }
                case "swipeup":
                    {
                        orbitX += Microsoft.Xna.Framework.MathHelper.ToRadians(15);
                        tbMessage.Text = "orbit up";
                        break;
                    }
                case "swipedown":
                    {
                        orbitX -= Microsoft.Xna.Framework.MathHelper.ToRadians(15);
                        tbMessage.Text = "orbit down";
                        break;
                    }

                //Kinect gesture template commands
                case "circle":
                    {

                        if (scene.Camera.Position.Z > 0.75f)
                        {
                            scene.Camera.Position += zoomInVector * 5;
                        }
                        tbMessage.Text = "zoomin";
                        break;
                    }
                case "circle2":
                    {
                        scene.Camera.Position += zoomOutVector * 5;
                        tbMessage.Text = "zoomout";
                        break;
                    }
            }
        }

Possible Extensions

After posting this code, I added an experimental stretch vector control for zooming and 2 axis twisting of planets. These are activated by voice: ‘vector twist’, ‘vector zoom’, and ‘vector off.’ The Map control side of gesture commands could also benefit from some easing function animations. Another avenue of investigation would be some type of pointer intersection using a ray to indicate planet surface locations for events.

Summary

Even though Kinect browser control is not prime time material yet, it is a lot of experimental fun! The MoonViewer control experiment is relatively primitive. Cursor movement and click using posture detection and hand tracking is also feasible, but fine movement is still a challenge. Two hand vector controlling for 3D scenes is also promising and integrates very well with SL5 XNA immediate mode graphics.

Kinect 2.0 and NearMode will offer additional granularity. Instead of large swipe gestures, finger level manipulation should be possible. Think of 3D voxel space manipulation of subsurface geology, or thumb and forefinger vector3 twisting of LiDAR objects, and you get an idea where this could go.

The merger of TV and internet holds promise for both whole body and NearMode Kinect interfaces. Researchers are also adapting Kinect technology for mobile as illustrated by OmniTouch.

. . . and naturally, lip reading ought to boost the Karaoke crowd (could help lip synching pop singers and politicians as well).

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Fig 7 – Jupiter Moon Io

Paradise Lost

image

Fig 1 – web mapping utopia, location uncertain

“Not surprisingly, in a culture in which information was becoming standardized and repeatable, mapmakers began to exclude “paradise” from their charts on the grounds that its location was too uncertain.”

—Neil Postman, Technopoly (1992)

I recently spent a few hours re-reading some old books on the shelf. Neil Postman’s Technopoly triggered some reflection on the present state of web mapping. As a technophile, I tend to look forward to the next version of whatever with anticipation. Taking the longer view, however, can be a useful exercise.

Progress – yes, no, maybe?

Postman’s critique asserts that Technology is in the vanguard of illusory “progress.” That the impact of technology shapes deep things in a culture with unimagined side effects. The core technology of our current cultural turnover is electronics and the key utility is “Information,” its storage and flow. Information volume and velocity apparently grow exponentially over time loosely tracking the famous Moore’s Law time curve. Our web mapping subset of Technology is embedded in this Information ramp up, and we are still grappling with the confusion of Information and Knowledge, resulting from an accelerating information glut.

The principle of Information is popping up all over, from Claude Shannon’s Information Theory to Hawking-Berkenstein’s Black hole solution which surprisingly showed that the total Information content of a Black hole is proportional to the Planck square surface area of its event horizon (as opposed to a cubic volume relation). Naturally the concept of Information leaks into the soft sciences as well. Bit obsession is now woven into Western economic fabric with the assumption of continuous progress.

Sociologically, this all leads to a breakup of previous generations of “knowledge monopolies” and a hyper-sensitivity to initial conditions, (the old Ray Bradbury crushed butterfly scenario at the root of chaos theory). The upheaval is met with a kind of assumed optimism, an unquestioned utopian view of progress around the benefits of modern technology. Information is good, right? More information faster is even better! Web maps contribute more information faster, so web mapping is on the side of the Good, the True, and the Beautiful. Naturally web maps can be quite beautiful, whatever that means subjectively.

The age of typography, ushered into Western culture by Gutenberg, had profound and enduring effects on history and culture, affecting everything – from the Reformation and the rise of Democratic Nationalism to our educational bureaucracy and even common definitions of truth and knowledge. But not until Marshall McLuhan were the typographic origins of these effects popularly visible, and only in retrospect. The electronic age, in its current internet iteration, is undoubtedly creating similarly profound dislocations, whose consequences are not at all apparent at present. Unintended side effects are just that, unintended. Consequences are unintended, because they are unknowable.

“Technology solved the problem of information scarcity, the disadvantages of which were obvious. But it gave no warnings about the danger of information glut, the disadvantages of which were not seen so clearly, the long range result – information chaos.”

 

“The world has never before been confronted with information glut and has hardly had time to reflect on its consequences.”

—Neil Postman, Technopoly (1992)

Whither web mapping?

So the question at hand revolves around the smaller microcosm of mapping in the internet era. That an ever growing amount of this information flood is geospatial is indisputable. Computing mobility adds terrestrial location to all business and social enterprise – Tweets to Facebook, Fleet Tracking to Risk Analysis are increasingly tethered to spatial attributes. Maps take all of these streams into a symbolic spatial representation, which filters for location. To a mapmaker everything is a map and terra incognita has long since vanished.

Web mapping adds an element of exploration, with zoom and pan flight through these abstract spaces, that mirrors movement in our physical world. Our community is also wont to add controls affording endless tinkering with the form, as if one more contribution to universal “Choice fatigue” will add value. But Google glommed on to the real deal. In a state of information overload, the key to riches is meaningful information reduction. Simplification is the heart of search. Web mapping is one more filtering approach reducing information along the axis of spatial proximity.

Do interactive maps add seriously to comprehension or just to entertainment, as simply a novelty? Cartographers relish pointing out this quandary to web developers and other mere mortals. In the web mapping community proliferating means can easily be confused with progress. Doesn’t it seem peculiar, for example, to attach any meaning whatsoever to charts of Kindergartener’s DIBELS scores, let alone median DIBELS scores charted on national school district polygons. Does it lead to anything but a bureaucratic illusion of some control over chaos? No child is better off for the graph (unless distant employment potential as an educational bureaucrat is considered relevant), and, “no child left behind” slogans to the contrary, the overthrow of typography based education proceeds apace in a confusing melee of winners and losers. The application of numeracy to every conceivable problem like this elevates modeling to mythic proportions.

“When a technology becomes mythic, it is always dangerous because it is then accepted as it is, and is therefore not easily susceptible to modification or control.”

—Neil Postman, Technopoly (1992)

image

What is a map but a modeling technology, a symbolic abstraction of space to visualize a formulaic concept? Maps are all entangled with mathematical models, ellipsoids, surfaces, and transforms, but are we guilty of mythically inflating the power of maps to communicate something of the Good, the True and the Beautiful? Does the proliferation of web maps, for instance, alter the injustice of Atanas Entchev’s incarceration for the so called “crime“of immigration? Likely not, and in fact, may contribute to the irony of an ICE database assigning the Entchev family a spatial attribute coinciding with some “Community Education Center” in Newark, NJ.

“Our inventions are wont to be pretty toys, which distract our attention from serious things. They are but improved means to an unimproved end, an end which it was already but too easy to arrive at.”

—Henry David Thoreau, Walden (1854), p. 42

Another pillar of cyber utopian thought is the inevitability of improved community with improved connectivity. The meteoric rise of Facebook exemplifies this confusion. For in fact Facebook is faceless, not anonymous, but prone to carefully crafted pseudonymous identities. Unintended messages ripple across unknowable communities, and histories, whether wanted or unwanted, retain regrettably long tails. Twitter, as well, champions brevity while fragmenting communication across a ghostly crowd of undisclosed persons.

“The great communication that we have today can lead to complete depersonalization. Then one is just swimming in a sea of communication and no longer encounters persons at all.”

—Benedict XVI “Light of the World” p59 facebook

Ray Kurzweil’s anticipation of the Coming Singularity includes human/non-human relationships via digital intermediaries, a thought with somewhat disturbing implications. Knowledge of location across an intermediary network matters little to human relationships and adding non-human intelligence to the mix is only disturbing. Real human relationships have deeper currents than high velocity information or spatial attribution. Studies in the educational community have repeatedly shown, for instance, that the presence of a real teacher is overwhelmingly more effective than video or online classes. To state the obvious, face to face renders location aware apps irrelevant and leaves artificial intelligence firmly anchored in the creepy category.

image

Robot Teacher?

Assumptions of all goodness by Cyber Utopians are not at all justified as remarked by Evgeny Morozov in The Internet in Society: Empowering and Censoring Citizen? Enduring histories on Facebook, subject to examination by Iranian intelligence for hardly promising ends, should be unsettling to all but the grimmest of Marxist utopians. Doubtless a few stray Stalinist at Duke and Zuccotti Park are taking notes on new media and the social web.

image

Evgeny’s passing point about "cyber captivity" underlines a growing problem of lost opportunity. The prescience of Alduous Huxley’s Soma comes to mind. Does obsessive gaming, for example, reduce higher value opportunities for learning, productivity, and human relations? Do vast iTune libraries subtract from the net benefit of personal mastery of a musical instrument? These calculations are impossible to quantify and really revolve around deeper questions of spiritual significance, sub specie aeternitatis.

More information faster is not necessarily a net positive in another sense. Proliferating conspiracy theories only corroborate Neil Postman’s shuffled deck analogy, that a disintegrating information context conditions perception to credulity. Anything is believable because the next card is experienced as random. Unwarranted credulity paves the way to tyranny as recent history has shown all too tragically. The Rwandan genocide, less than 10 years ago, was incited by incredulous claims aired to a credulous public in creepy Goebbels fashion. The future specter of OsGeo web maps delineating the boundaries of inyenzi (cockroach in Kinyarwandan), does little to encourage optimism.

“The fact is, there are few political, social, and especially personal problems that arise because of insufficient information. Nonetheless, as incomprehensible problems mount, as the concept of progress fades, as meaning itself becomes suspect, the Technopolist stands firm in believing that what the world needs is yet more information.”

—Neil Postman, Technopoly (1992)

Summary

These may all be rather marginally Luddite issues. The genuine “terra incognita” of information technology, and consequently web mapping, is the tectonic plate of culture. What kind of global cultural, economic, and political earthquakes have been set in motion? What tidal wave of changing perceptual process is yet to be hailed from the yardarm?

Kind of exciting to think about.

Paradise Lost? Please report to Lost and Found.

FOSS4G 2011

I was privileged to spend a few days at FOSS4G in Denver. It’s quite the opportunity to have an international convergence of GIS developers handily just a bus ride up the highway. I could walk among the current luminaries of OsGeo, Arnulf Christl, Paul Ramsey, Frank Warmerdam, Simone Giannecchini, and so on and on, and trade a handshake with the hard working front range folks, Peter Batty, Brian Timoney (way to go Brian!), and Matt Kruzemark too. The ideas are percolating in every corner, but it strikes me in an odd way that this world has changed irrevocably. The very technology that makes Geo FOSS possible is also making it, of all things, mundane.

Open Standards

It wasn’t that long ago that OGC standards were brand new. Each release anticipated a new implementation for discovery. Now implementations proliferate helter skelter. OGC services? Take your pick. Or, slice, dice, and merge with MapProxy. Map Tiling engines line up like yogurt brands at Whole Foods. GeoFOSS has progressed a long way from naive amazement over OGC WMS connections. WFS and WCS have already passed their respective moments of glorious novelty.

This is the year of WPS, Web Processing Service, and the hope of constructing webs of analysis chains from disparate nodes. Each node adds a piece toward a final solution. Anyone with some experience using FME Transformers has some idea of what this looks like on the desktop. WPS moves analytic workflows into open standards and onto the web. Ref: 52north.org and GeoServer Ext

FME Workbench
Fig2 – example of FME Workbench processing chain

On the floor at FOSS4G 2011

In a different vein, the next release of PostGIS will push raster analysis right into SQL. This is new territory for PostGIS and elevates a raster datatype to the same level as geometry. This PostGIS Raster Functions page gives some flavor for the raster functions soon to be available when 2.0 releases. Ever needed a raster reprojection?

raster ST_Transform(raster rast, integer srid, double precision scalex, double precision scaley, text algorithm=NearestNeighbor, double precision maxerr=0.125);

Algorithm options are: ‘NearestNeighbor’, ‘Bilinear’, ‘Cubic’, ‘CubicSpline’, and ‘Lanczos.’

Wow ST_MapAlgebra! And on the roadmap MapAlgebra raster on raster! MySQL and SQL Server have quite the feature curve to follow as PostGIS forges ahead.

(See even the slightly jaded can catch some excitement at FOSS4G.)

Numerous workshops dealt with javascript map frameworks OpenLayers, MapQuery, GeoExt, Leaflet. The html5 trend is underlined by news flashes from the concurrent Microsoft Build Conference.

“For the web to move forward and for consumers to get the most out of touch-first browsing, the Metro style browser in Windows 8 is as HTML5-only as possible, and plug-in free. The experience that plug-ins provide today is not a good match with Metro style browsing and the modern HTML5 web.” Steven Sinofsky

CouchDB/GeoCouch was present although “eventually consistent” NoSQL seems less pressing.

Although Oracle is trying hard to break Java, it is still a popular platform among FOSS projects. The Javascript platform is a growth industry with the help of backend tools like Node.js, html5 WebSockets, and Asynchronous WebWorkers. C/C++ takes away wins in the popular performance shootout.

3D WebGL made an appearance with WebGLEarth, while Nasa World Wind still has an occasional adherent.

Open Software

With over 900 attendees, the small world of FOSS seems all of a sudden crowded, jostling through accelerating growth. The Ordnance Survey was represented at a plenary session, “We have to learn to embrace open source. We want to use OS. We want to encourage OS.” Who’d of ever thought? FCC.gov opens their kimono in a big way with data transparency and OS APIs. Work shop topics include such things as: “Open Source Geospatial Software Powering Department of Defense Installation and Environment Business Systems,” or catch this, “The National Geospatial-Intelligence Agency OSS Challenge.” Is this the new Face of FOSS?

Open Bureaucracy?

Such bureaucracies know little of agile. The memorable phrase “embrace, extend, extinguish” comes to mind. But who embraces whom? Is the idea of FOSS and its larger www parent, a trend that eventually extinguishes bureaucracy or does the ancient ground of bureaucratic organization trump connection? Byzantine bureaucracy has been around since … well the Byzantine Empire, and given human nature is likely enduring. But, what does a “flat” Byzantine Bureaucracy look like? How about crowd sourced Byzantia? Would an aging Modernity mourn the loss of “Kafkaesque” as an adjective?

Assuming growth continues, will success reduce the camaraderie of community as a motivation? Just this year we hear of OSM’s Steve Coast sidling into Microsoft, followed a little later by GDAL’s Frank Warmerdam beaming up into the Google mother ship. The corporate penalty, of course, is the loss of personal intellectual property. In other words, will Steve Coast’s imaginative ideas now fall under the rubric, “all your base are belong to us,” and Frank’s enduring legacy recede into the patent portfolio of “Do no evil?” FOSS4G halls are still filled with independent consultants and academics, but a significant corporate representation is evident by this apparent oxymoron, a presentation by ESRI, “Open Source GIS Solutions.”

Some Perspective:

The GIS nervous system grows connections around the world faster than a three year old’s brain. OK, maybe I exaggerate, after all, “During the first three years, your child’s brain establishes about 1,000 trillion nerve connections!” Really, how many connections are there in the World Wide Web. For all its impact on life, our beloved internet encompasses the equivalent of what, a few cubic centimeters of a single infant’s anatomy.

Open Geospatial and FOSS are just a small part of this minor universe, but it’s easy to forget that even ten years ago this all hardly existed. “The first Interoperability Program testbed (Web Mapping Testbed) appeared in 1999.” About the same time Frank Warmerdam started GDAL and the GFOSS engines started.

I still recall the wonder of downloading Sol Katz utilities from BLM’s ftp. The novelty of all this data free to use from the USGS was still fresh and amazing. Sol sadly died before seeing his legacy, but what a legacy. The Sol Katz award this year went to Java Topology Suite’s well deserving Martin Davis.

Alice in Mirrorland – Silverlight 5 Beta and XNA

“In another moment Alice was through the glass, and had jumped lightly down into the Looking-glass room”

Silverlight 5 Beta was released into the wild at MIX 11 a couple of weeks ago. This is a big step for mirror land. Among many new features is the long anticipated 3D capability. Silverlight 5 took the XNA route to 3D instead of the WPF 3D XAML route. XNA is closer to the GPU with the time tested graphics rendering pipeline familiar to Direct3D/OpenGL developers, but not so familiar to XAML developers.

The older WPF 3D XAML aligns better with X3D, the ISO sanctioned XML 3D graphics standard, while XNA aligns with the competing WebGL javascript wrapper for OpenGL. Eventually XML 3D representations also boil down to a rendering pipeline, but the core difference is that XNA is immediate mode while XML 3D is kind of stuck with retained mode. Although you pick up recursive control rendering with XML 3D, you lose out when it comes to moving through a scene in the usual avatar game sense.

From a Silverlight XAML perspective, mirror land is largely a static machine with infrequent events triggered by users. In between events, the machine is silent. XAML’s retained mode graphics lacks a sense of time’s flow. In contrast, enter XNA through Alice’s DrawingSurface, and the machine whirs on and on. Users occasionally throw events into the machine and off it goes in a new direction, but there is no stopping. Frames are clicking by apace.

Thus time enters mirror land in frames per second. Admittedly this is crude relative to our world. Time is measured out in the proximate range of 1/20th to 1/60th a second per frame. Nothing like the cusp of the moment here, and certainly no need for the nuance of Dedekind’s cut. Time may be chunky in mirror land, but with immediate mode XNA it does move, clicking through the present moment one frame at a time.

Once Silverlight 5 is released there will be a continuous XNA API across Microsoft’s entire spectrum: Windows 7 desktops, Windows 7 phones, XBox game consoles, and now the browser. Silverlight 5 and WP7 implementations are a subset of the full XNA game framework available to desktop and XBox developers. Both SL5 and WP7 will soon have merged Silverlight XNA capabilities. For symmetry sake XBox should have Silverlight as apparently announced here. It would be nice for a web browsing XBox TV console.

WP7 developers will need to wait until the future WP7 Mango release before merging XNA and Silverlight into a single app. It’s currently an either/or proposition for the mobile branch of XNA/SL.

At any rate, with SL5 Beta, Silverlight and 3D XNA now coexist. The border lies at the <DrawingSurface> element:

<DrawingSurface Draw="OnDraw" SizeChanged="DrawingSurface_SizeChanged" />

North of the border lies XML and recursive hierarchies, a largely language world populated with “semantics” and “ontologies.” South of the border lies a lush XNA jungle with drums throbbing in the night. Yes, there are tropical white sands by an azure sea, but the heart of darkness presses in on the mind.

XAML touches the academic world. XNA intersects Hollywood. It strikes me as one of those outmoded Freudian landscapes so popular in the 50’s, the raw power of XNA boiling beneath XAML’s super-ego. I might also note there are bugs in paradise, but after all this is beta.

Merging these two worlds causes a bit of schizophrenia. Above is Silverlight XAML with the beauty of recursive hierarchies and below is all XNA with its rendering pipeline plumbing. Alice steps into the DrawingSurface confronting a very different world indeed. No more recursive controls beyond this border. Halt! Only immediate mode allowed. The learning curve south of the border is not insignificant, but beauty awaits.

XNA involves tessellated models, rendering pipelines, vertex shaders, pixel shaders, and a high level shading language, HLSL, accompanied by the usual linear algebra suspects. Anytime you run across register references you know this is getting closer to hardware.

…a cry that was no more than a breath: “The horror! The horror!”

sampler2D CloudSampler : register(s0);
static const float3 AmbientColor = float3(0.5f, 0.75f, 1.0f);
static const float3 LampColor = float3(1.0f, 1.0f, 1.0f);
static const float AmbientIntensity = 0.1f;
static const float DiffuseIntensity = 1.2f;
static const float SpecularIntensity = 0.05f;
static const float SpecularPower = 10.0f;
			.
			.

Here is an overview of the pipeline from Aaron Oneal’s MIX talk:

So now that we have XNA it’s time to take a spin. The best way to get started is to borrow from the experts. Aaron Oneal has been very kind to post some nice samples including a game engine called Babylon written by David Catuhe.

The Silverlight 5 beta version of Babylon uses Silverlight to set some options and SL5 DrawingSurface to host scenes. Using mouse and arrow keys allows the camera/avatar to move through the virtual environment colliding with walls etc. For those wishing to get an idea of what XNA is all about this webcafe model in Babylon is a good start.

The models are apparently produced in AutoCAD 3DS and are probably difficult to build. Perhaps 3D point clouds will someday help, but you can see the potential for navigable high risk complex facility modeling. This model has over 60,000 faces, but I can still walk through exploring the environment without any difficulty and all I’m using is an older NVidia motherboard GPU.

Apparently, SL5 XNA can make a compelling interactive museum, refinery, nuclear facility, or WalMart browser. This is not a stitched pano or photosynth interior, but a full blown 3D model.

You’ve gotta love that late afternoon shadow affect. Notice the camera is evidently held by a vampire. I checked carefully and it casts no shadow!

But what about mapping?

From a mapping perspective the fun begins with this solar wind sample. It features all the necessary models, and shaders for earth, complete with terrain, multi altitude atmosphere clouds, and lighting. It also has examples of basic mouse and arrow key camera control.

Solar Wind Globe
Fig 4 – Solar Wind SL5 XNA sample

This is my starting point. Solar Wind illustrates generating a tessellated sphere model with applied textures for various layers. It even illustrates the use of a normal (bump) map for 3D effects on the surface without needing a tessellated surface terrain model. Especially interesting is the use of bump maps to show a population density image as 3D.

My simple project is to extend this solar wind sample slightly by adding layers from NASA Neo. NASA Neo conveniently publishes 45 categories and 129 layers of a variety of global data collected on a regular basis. The first task is to read the Neo GetCapabilities XML and produce the TreeView control to manage such a wealth of data. The TreeView control comes from the Silverlight Toolkit project. Populating this is a matter of reading through the Layer elements of the returned XML and adding layers to a collection which is then bound to the tree view’s ItemsSource property.

    private void CreateCapabilities111(XDocument document)
    {
        //WMS 1.1.1
        XElement GetMap = document.Element("WMT_MS_Capabilities").Element("Capability")
            .Element("Request").Element("GetMap").Element("DCPType")
            .Element("HTTP").Element("Get").Element("OnlineResource");
        XNamespace xlink = "http://www.w3.org/1999/xlink";
        getMapUrl = GetMap.Attribute(xlink + "href").Value;
        if (getMapUrl.IndexOf("?") != -1) getMapUrl =
                  getMapUrl.Substring(0, getMapUrl.IndexOf("?"));

        ObservableCollection layers = new ObservableCollection();
        foreach (XElement element in
document.Element("WMT_MS_Capabilities").Element("Capability")
                .Element("Layer").Descendants("Layer"))
        {
            if (element.Descendants("Layer").Count() > 0)
            {
                WMSLayer lyr0 = new WMSLayer();
                lyr0.Title = (string)element.Element("Title");
                lyr0.Name = "header";
                foreach (XElement element1 in element.Descendants("Layer"))
                {
                    WMSLayer lyr1 = new WMSLayer();
                    lyr1.Title = (string)element1.Element("Title");
                    lyr1.Name = (string)element1.Element("Name");
                    lyr0.sublayers.Add(lyr1);
                }

                layers.Add(lyr0);
            }
        }
        LayerTree.ItemsSource = layers;
    }

Once the tree is populated, OnSelectedItemChanged events provide the trigger for a GetMap request to NASA Neo returning a new png image. I wrote a proxy WCF service to grab the image and then write it to png even if the source is jpeg. It’s nice to have an alpha channel for some types of visualization.

The difficulty for an XNA novice like myself is understanding the hlsl files and coming to terms with the rendering pipeline. Changing the source image for a Texture2D shader requires dropping the whole model, changing the image source, and finally reloading the scene model and pipeline once again. It sounds like an expensive operation but surprisingly this re-instantiation seems to take less time than receiving the GetMap request from the WMS service. In WPF it was always interesting to put a Video element over the scene model, but I doubt that will work here in XNA.

The result is often a beautiful rendering of the earth displaying real satellite data at a global level.

Some project extensions:

  • I need to revisit lighting which resides in the cloud shader hlsl. Since the original cloud model is not real cloud coverage, it is usually not an asset to NASA Neo data. I will need to replace the cloud pixel image with something benign to take advantage of the proper lighting setup for daytime.
  • Next on the list is exploring collision. WPF 3D provided a convenient RayMeshGeometry3DHitTestResult. In XNA it seems getting a point on the earth to trigger a location event requires some manner of collision or Ray.Intersects(Plane). If that can be worked out the logical next step is grabbing DEM data from USGS for generating ground level terrain models.
  • There is a lot of public LiDAR data out there as well. Thanks to companies like QCoherent, some of it is available as WMS/WFS. So next on the agenda is moving 3D LiDAR online.
  • The bump map approach to displaying variable geographic density as relief is a useful concept. There ought to be lots of global epidemiology data that can be transformed to a color density map for display as a relief bump map.

Lots of ideas, little time or money, but Silverlight 5 will make possible a lot of very interesting web apps.

Helpful links:
Silverlight 5 Beta: http://www.silverlight.net/getstarted/silverlight-5-beta/
Runtime: http://go.microsoft.com/fwlink/?LinkId=213904

Silverlight 5 features:
http://i1.silverlight.net/content/downloads/silverlight_5_beta_features.pdf?cdn_id=1
“Silverlight 5 now has built-in XNA 3D graphics API”

XNA: http://msdn.microsoft.com/en-us/aa937791.aspx
Overview

NASA Neo: http://localhost/NASA-Neo/publish.htm

Babylon Scenes: Michel Rousseau, courtesy of Bewise.fr

Babylon Engine: David Catuhe / Microsoft France / DPE

Summary:

“I am real!” said Alice, and began to cry.

“You won’t make yourself a bit realler by crying,” Tweedledee remarked: “there’s nothing to cry about.”

“If I wasn’t real,” Alice said – half-laughing through her tears, it all seemed so ridiculous – “I shouldn’t be able to cry.”

WebBIM? hmmm .. Bing BIM?

BIM or Building Information Modeling isn’t exactly news. I guess I tend to think of it as a part of AEC, starting back in the early generations of CAD, as a way to manage a facility in the aftermath of design and construction. BIM is after all about Buildings, and Buildings have been CAD turf all these many years. Since those early days of FM, CAD has expanded into the current BIM trend with building lifecycle management that is swallowing up larger swathes of surrounding environments.

BIM models are virtual worlds, ‘mirror lands’ of a single building or campus. As BIM grows the isolated BIM models start to aggregate and bump up against the floor of web mapping, the big ‘Mirror Land’. One perspective is to look at a BIM model as a massively detailed Bill of Material (BIM<=>BOM . . bing) in which every component fitted into the model is linked to additional data for specification, design, material, history, approval chains, warranties, and on and on. BIM potentially becomes one massively connected network of hyperlinks with a top level 3D model that mimics the real world.

Sound familiar? – BIM is a sub-internet on the scale of a single building with an interface that has much in common with web mapping. Could this really be yet another reincarnation of Ted Nelson’s epic Xanadu Project, the quixotic precursor of today’s internet?

Although of relatively recent origins, BIM has already spawned its own bureaucratic industry with the likes of NBIMS replete with committees, charters, and governance capable of seriously publishing paragraphs like this:

“NBIM standards will merge data interoperability standards, content values and taxonomies, and process definitions to create standards which define “business views” of information needed to accomplish a particular set of functions as well as the information exchange standards between stakeholders.”

No kidding, “taxonomies”? I’m tempted to believe that ‘Information’ was cleverly inserted to avoid the embarrassing eventuality of an unadorned “Building Model.” Interesting how Claude Shannon seems to crop up in a lot of acronyms these days: BIM, GIS, NBIMS, ICT, even IT?

BIM has more recently appeared on the GIS radar with a flurry of discussion applying GIS methods to BIM. Here, for example are a couple of posts with interesting discussion: SpatialSustain, GeoExpressions, and Vector One. Perhaps this is just another turf battle arising in the CAD versus GIS wars. I leave that for the GISCIers and NBIMSers to decide.

My interest is less in definition and more an observation that buildings too are a part of the rapidly growing “Mirror Land” we call web maps. Competing web maps have driven resolution down to the region of diminishing returns. After all, with 30cm commonly available, is 15cm that much more compelling? However, until recently, Mirror Land has been all about maps and the wide outside world. Even building models ushered in with SketchUp are all about exteriors.

The new frontier of web mapping is interior spaces, “WebBIM,” “Bing BIM” ( Sorry, I just couldn’t resist the impulse). Before committing to national standards, certifications, and governance taxonomies perhaps we need to just play with this a bit.

We have Bing Maps Local introducing restaurant photoscapes. Here’s an example of a restaurant in Boston with a series of arrow connected panoramas for virtual exploration of the interior.

And another recent Bing Maps introduction, mall maps. Who wants to be lost in a mall, or are we lost without our malls?

And then in the Google World Art Projects explore museums. Cool, Streetside Inside!

It’s not obvious how far these interior space additions will go in the future, but these seem to be trial balloons floated for generating feedback on interior extensions to the web map mirror world. At least they are not introduced with full fledged coverage.

“Real” BIM moves up the dimension chain from 2D to 3D and on to 4 – 5D, adding time and cost along the way. Mirror Land is still caught in 2-3D. The upcoming Silverlight 5 release will boost things toward the 3-4D. Multi-verse theories aside (now here’s a taxonomy to ponder – the Tegmark cosmological taxonomy of universes), in the 3-4D range full WebBIM can hit the streets. In the meantime the essential element of spatially hyperlinked data is already here for the curious to play with.

So what’s a newbie Web BIMMER to do? The answer is obvious, get a building plan and start trying a few things. Starting out in 2D, here is an approach: get a building floorplan, add it to a Bing Maps interface, and then do something simple with it.

Step 1 – Model a building

CAD is the place to start for buildings. AEC generates floorplans by the boatload and there are even some available on line, but lacking DWG files the next possibility is using CAD as a capture tool. I tried both approaches. My local grocery store has a nice interior directory that is easily captured in AutoCAD by tracing over the image:

King Soopers Store Directory
Fig 5 – King Soopers Store Directory (foldout brochure)

As an alternative example of a more typical DWG source, the
University of Alaska
has kindly published their floor plans on the internet.

In both scenarios the key is getting the DWG into something that can readily be used in a web map application. Since I’m fond of Bing Silverlight Map Control, the goal is DWG to XAML. Similar things can be done with SVG, and will be as HTML5 increases its reach, and probably even in KML for the Googler minded. At first I thought this would be as easy as starting up Safe Software’s FME, but XAML is not in their writers list, perhaps soon. Next, I fell back to the venerable DXF text export with some C# code to turn it into XAML. This was actually fairly easy with the DXF capture of my local grocery store. I had kept the DWG limited to simple closed polylines and text, separated by layer names.

Here is the result:

Now on to more typical sources, DWG files which are outside of my control. Dealing with arcs and blocks was more than I wanted, so I took an alternative path. FME does have an SVG writer. SVG is hauntingly similar to XAML (especially haunting to W3C), and writing a simple SVG to XAML translator in C# was easier than any other approach I could think of. There are some XSLT files for SVG to XAML, but instead I took the quick and dirty route of translating SVG text to XAML text in my own translator giving me some more control.

Here is the result:

Step 2 – Embed XAML into a Bing Map Control interface

First I wrote a small webapp that allows me to zoom Bing maps aerial to a desired building and draw a polyline around its footprint. This polyline is turned into a polygon XAML snippet added to a TextBox suitable for cut/paste as a map link in my Web BIM experiment.

 <m:MapPolygon Tag="KingSoopers2" x:Name="footprint_1"
 Fill="#FFfdd173" Stroke="Black" StrokeThickness="1" Opacity="0.5"
MouseLeftButtonUp="MapPolygon_MouseLeftButtonUp">
<m:MapPolygon.Locations>
39.05779345,-104.84322060
39.05772368,-104.84321926
39.05770910,-104.84302480
39.05771014,-104.84290947
39.05772159,-104.84277536
39.05776116,-104.84277804
39.05776429,-104.84243204
39.05833809,-104.84248434
39.05833288,-104.84283303
39.05836204,-104.84284510
39.05835996,-104.84313880
39.05832872,-104.84313880
39.05832663,-104.84340836
39.05825478,-104.84340568
39.05825374,-104.84354113
39.05821000,-104.84353979
39.05820792,-104.84369670
39.05779137,-104.84367792
39.05779345,-104.84322060
</m:MapPolygon.Locations>
</m:MapPolygon>

As a demonstration, it was sufficient to simply add this snippet to a map control. The more general method would be to create a SQL table of buildings that includes a geography column of the footprint suitable for geography STIntersects queries. Using a typical MainMap. ViewChangeEnd event would then let the UI send a WCF query to the table, retrieving footprints falling into the current viewport as a user navigates in map space. However, the real goal is playing with interior plans and I left the data connector feature for a future enhancement.

In order to find buildings easily, I added some Geocode Service calls for an Address finder. The footprint polygon with its MouseLeftButtonUp event leads to a NavigationService that moves to the desired floor plan page. Again generalizing this would involve keeping these XAML floor plans in a SQL Azure Building table for reference as needed. A XAML canvas containing the floor plans would be stored in a BLOB column for easy query and import to the UI. Supporting other export formats such as XAML, SVG, and KML might best be served by using a GeometryCollection in the SQL table with translation on the query response.

Step 3 – Do something simple with the floorplans

Some useful utilities included nesting my floorplan XAML inside a <local:DragZoomPanel> which is coded to implement some normal pan and zoom functions: pan with left mouse, double click zoom in, and mouse wheel zoom +/-. Mouse over text labeling helps identify features as well. In addition, I was thinking about PlaneProjections for stacking multiple floors so I added some slider binding controls for PlaneProjection attributes, just for experimentation in a debug panel.

Since my original King Soopers image is a store directory an obvious addition is making the plan view into a store directory finder.

I added the store items along with aisles and shelf polygon id to a table accessed through a WCF query. When the floorplan is initialized a request is made to a SQL Server table with this directory item information used to populate a ListBox. You could use binding, but I needed to add some events so ListBoxItems are added in code behind.

Mouse events connect directory entries to position polygons in the store shelves. Finally a MouseLeftButtonUp event illustrates opening a shelf photo view which is overlaid with a sample link geometry to a Crest product website. Clicks are also associated with Camera Icons to connect to some sample Photosynthes and Panoramas of store interior. Silverlight 5 due out in 2011 promises to have Silverlight integration of Photosynthe controls as well as 3D.

Instead of a store directory the UAA example includes a simple room finder which moves to the corresponding floor and zooms to the room selected. My attempts at using PlaneProjection as a multi floor stack were thwarted by lack of control over camera position. I had hoped to show a stack of floor plans at an oblique view with an animation for the selected floor plan sliding it out of the stack and rotating to planar view. Eventually I’ll have a chance to revisit this in SL5 with its full 3D scene graph support.

Where are we going?

You can see where these primitive experiments are going: Move from a Bing Map to a Map of interior spaces and now simple Locators can reach into asset databases where we have information about all our stuff. The stuff in this case is not roads, addresses, and shops, but smaller stuff, human scale stuff that we use in our everyday consumer and corporate lives. Unlike rural cultures, modern western culture is much more about inside than outside. We spend many more hours inside the cube than out, so a Mirror Land where we live is certainly a plausible extension, whether we call it CAD, GIS, BIM, FM, or BINGBIM matters little.

It’s also noteworthy that this gives vendors a chance to purchase more ad opportunities. After all, our technology is here to serve a consumer driven culture and so is Mirror Land.

Interior spaces are a predictable part of Mirror Land and we are already seeing minor extensions. The proprietary and private nature of many interior spaces is likely to leave much out of public mapping. However, retail incentives will be a driving force extending ad opportunities into personal scale mapping. Eventually Mobile will close the loop on interior retail space, providing both consumer location as well as local asset views. Add some mobile camera apps, and augmented reality will combine product databases, individualized coupon links, nutritional content, etc to the shelf in front of you.

On the enterprise side, behind locked BIM doors, Silverlight with its rich authentication framework, but more limited mobile reach, will play a part in proprietary asset management which is a big part of FM, BM, BIM ….. Location of assets is a major part of the drive to efficiency and covers a lot of ground from inventory, to medical equipment, to people.

Summary:

This small exercise will likely irk true NBIMSers who will not see much “real” BIM in a few floor plans. So I hasten to add this disclaimer, I’m not really a Web BIMer or even a Bing BIMer, but I am looking forward to the extension of Mirror Land to the interior spaces I generally occupy.

Whether GIS analysis reaches into web mapped interiors is an open question. I’m old enough to remember when there were “CAD Maps” and “Real GIS”, and then “Web Maps” and “Real GIS.” Although GIS (real, virtual, or otherwise) is slowly reaching deeper into Mirror Land, we are still a long way from NBIMS sanctioned “Real” WebBIM with GIS analysis. But then that means it’s still fun, right?

(Silverlight BusinessApplication , Membership on Azure) => To Map || Not To Map

We owe Alonzo Church for this one:

    WebContext.Current.Authentication.LoggedIn += (se, ev) =>
    {
       Link2.Visibility = Visibility.Visible;
    };

    WebContext.Current.Authentication.LoggedOut += (se, ev) =>
    {
        Link2.Visibility = Visibility.Collapsed;
    };

The λ calculus “goes to” Lambda Expressions now in C#, turning mere programmers into logicians. We share in the bounty of Alonzo’s intellect in some remote fashion. Likely others understand this functional proof apparatus, but for me it’s a mechanical thing. Put this here and that there, slyly kicking an answer into existence. Is a view link visible or is it not?

Here we are not concerned with “the what” of a map but a small preliminary question, “whether to map at all?”

Azure provides a lot of cloud for the money. Between SQL Azure, blob storage, and hosted services, both web and worker roles, there are a lot of very useful resources. All, except SQL Azure, currently include built in scaling and replication. Azure SQL Server scaling is still awaiting the release of federation at some point in the future.

Visual Studio 2010 adds a Cloud toolkit with template ready services (not to be confused with “shovel ready”). One template that is interesting is the ASP .NET template combined with an Azure hosted Web Role service. The usefulness here is the full ASP .NET authentication and profile capability. If you need simple authentication, profile, and registration built on the ASP .NET model it is all here.

The goal then is to leverage the resourceful templates of ASP .NET authentication, modify this to a Silverlight version (which implies a Bing Map Control is in the future, along with some nifty transition graphics), and finally deploy to Azure.

And now for the recipe

authentication screen shot
Fig1 – open a new VS2010 project using the Cloud template

authentication screen shot
Fig2 – add an ASP .NET Web Role

authentication screen shot
Fig3 – click run to open in local development fabric with login and registration

This is helpful and works fine in a local dev fabric.

Now on to Azure:

First create a Storage Account and a Hosted Service.

authentication screen shot
Fig4 – Storage Account for use in publishing and diagnostics logs

authentication screen shot
Fig5 – Azure control manager

authentication screen shot
Fig6 – create a SQL Azure instance to hold the aspnetdb

Now using VS2010 publish the brand new ASP .NET web role to the new Azure account.

Problem 1
However, publish to Azure and you will immediately face a couple of problems. First, the published Azure service is a Web Role not a VM, which means there is no local SQL Server accessible for attaching a default aspnetdb. SQL Azure is in its own separate instance. You will need to manually create the aspnetdb Database on a SQL Azure instance and then provide a connection string to this new SQL Azure in the Web Role.

Microsoft provides sql scripts adapted for providing this to SQL Azure:http://code.msdn.microsoft.com/KB2006191

Running these scripts in your Azure DB will create the following membership database and tables:

authentication screen shot
Fig7 – aspnetdb SQL Azure database

Since I like Silverlight better it’s probably time to dump the plain Jane ASP .NET in favor of the Silverlight Navigation version. Silverlight provides animated fades and flips to which most of us are already unconsciously accustomed.

In Visual Studio add a new project from the Silverlight templates. The Silverlight Business Application is the one with membership.

authentication screen shot
Fig8 – Silverlight Business Application

We are now swapping out the old ASP .NET Cloud Web Role with a Silverlight BusinessApplication1.Web

Step 1
Add reference assemblies WindowsAzure Diagnostic, ServiceRuntime, and StorageClient to BusinessApplication1.Web

Step 2
Copy WebRole1 WebRole.cs to BusinessApplication1.Web and correct namespace

Step 3
CloudService1 Roles right click to add Role in solution – BusinessApplication.Web
(Optional remove WebRole1 from Roles and remove WebRole project since it is no longer needed)

Step 4
Add a DiagnosticsConnectionString property to the Roles/BusinessApplication1.Web role that points to the Azure blob storage. Now we can add a DiagnosticMonitor and trace logging to the WebRole.cs

Step 5
Open BusinessApplication1.Web web.config, add connection string pointed at SQL Azure aspnetdb and a set of ApplicationServices:

<?xml version="1.0"?>
<configuration>
  <configSections>
    <sectionGroup name="system.serviceModel">
      <section name="domainServices"
type="System.ServiceModel.DomainServices.Hosting.DomainServicesSection,
 System.ServiceModel.DomainServices.Hosting, Version=4.0.0.0, Culture=neutral,
PublicKeyToken=31BF3856AD364E35" allowDefinition="MachineToApplication"
requirePermission="false" />
    </sectionGroup>
  </configSections>
    <connectionStrings>
        <remove name="LocalSqlServer"/>
        <add name="ApplicationServices" connectionString="Server=tcp:<SqlAzure
server>.database.windows.net;Database=aspnetdb;User
 ID=<username>;Password=<password>;Trusted_Connection=False;Encrypt=True;"
 providerName="System.Data.SqlClient" />
    </connectionStrings>


  <system.web>
    <httpModules>
      <add name="DomainServiceModule"
 type="System.ServiceModel.DomainServices.Hosting.DomainServiceHttpModule,
 System.ServiceModel.DomainServices.Hosting, Version=4.0.0.0, Culture=neutral,
 PublicKeyToken=31BF3856AD364E35" />
    </httpModules>
    <compilation debug="true" targetFramework="4.0" />


    <authentication mode="Forms">
      <forms name=".BusinessApplication1_ASPXAUTH" />
    </authentication>

      <membership defaultProvider="AspNetSqlMembershipProvider">
          <providers>
              <clear/>
              <add name="AspNetSqlMembershipProvider"
 type="System.Web.Security.SqlMembershipProvider"
connectionStringName="ApplicationServices"
                   enablePasswordRetrieval="false" enablePasswordReset="true"
 requiresQuestionAndAnswer="false" requiresUniqueEmail="false"
                   maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6"
 minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10"
                   applicationName="/" />
          </providers>
      </membership>

      <profile defaultProvider="AspNetSqlProfileProvider">
          <providers>
              <clear/>
              <add name="AspNetSqlProfileProvider"
 type="System.Web.Profile.SqlProfileProvider"
 connectionStringName="ApplicationServices" applicationName="/"/>
          </providers>
          <properties>
              <add name="FriendlyName"/>
          </properties>
      </profile>

      <roleManager enabled="false" defaultProvider="AspNetSqlRoleProvider">
          <providers>
              <clear/>
              <add name="AspNetSqlRoleProvider"
 type="System.Web.Security.SqlRoleProvider"
 connectionStringName="ApplicationServices" applicationName="/" />
              <add name="AspNetWindowsTokenRoleProvider"
type="System.Web.Security.WindowsTokenRoleProvider" applicationName="/" />
          </providers>
      </roleManager>
  

  </system.web>

  <system.webServer>
    <validation validateIntegratedModeConfiguration="false"/>
    <modules runAllManagedModulesForAllRequests="true">
      <add name="DomainServiceModule" preCondition="managedHandler"
          type="System.ServiceModel.DomainServices.Hosting.DomainServiceHttpModule
, System.ServiceModel.DomainServices.Hosting, Version=4.0.0.0, Culture=neutral,
 PublicKeyToken=31AS3856AD234E35" />
    </modules>
  </system.webServer>

  <system.serviceModel>
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true"
 multipleSiteBindingsEnabled="true" />
  </system.serviceModel>
</configuration>

Now we can publish our updated Silverlight Web Role to Azure.

authentication screen shot
Fig9 – publish to Azure

However, this brings us to problem 2

It turns out that there are a couple of assemblies that are missing from Azure’s OS but required for our Silverlight membership BusinessApplication. When an assembly is missing publish will continue cycling between initializing and stop without ever giving a reason for the endless loop.

When this happens I know to start looking at the assembly dlls. Unfortunately they are numerous. Without a message indicating which is at fault we are reduced to trial and error. Obviously the turnaround on publish to Azure is not incredibly fast. Debug cycles will take five to ten minutes so this elimination process is tedious. However, I spent an afternoon on this and can save you some time. The trick assemblies are:
    System.ServiceModel.DomainServices.Hosting
    System.ServiceModel.DomainServices.Server

To fix this problem:
Open references under BusinessApplication1.Web and click on the above two assemblies. Then go to properties “Copy Local” which must be set to True. This means that a publish to Azure will also copy these two missing assemblies from your local VS2010 environment up to Azure and publish will eventually run as expected.

The publish process then brings us to this:

authentication screen shot
Fig10 – Login

And this:

authentication screen shot
Fig11 – Register

That in turn allows the Alonzo λ magic:

            WebContext.Current.Authentication.LoggedIn += (se, ev) =>
            {
                Link2.Visibility = Visibility.Visible;
            };

Summary:

Well it works, maybe not as easily as one would expect for a Cloud template.

New Stuff

Some convergence stuff has been passing by my window recently. Too bad there isn’t more time to play, but here are a few items of note to the spatial world.

DataConnector screen shot
Silverlight 5 early early demo from Firestarter webcast

First a look ahead to Silverlight 5 due in 2011:

Silverlight Firestarter video

Some very interesting pre-release demos showcasing mesh graphics running at GPU speeds. WPF has had 3D mesh capability for a few years, but SL5 will add the same camera level control in 3D scene graphs to spice up delivery in the browser. There will be a whole new level of interesting possibilities with 3D in the browser as apparent in the Rosso demos above.



3D View of what?
So then 3D viewing, but how do you get a 3D image into the model in the first place? Well thanks to some links from Gene Roe, and interesting open source driver activity around the Kinect, here are some possibilities.

The obvious direction is a poor man’s 3d modeler. It won’t be too long until we see these devices in every corner of rooms supplementing the omnipresent security cameras with 3D views. (Nice to know that the security folks can wander around mirror land looking under tables and behind curtains.)

Well it could be worse, see DIY TSA scanner. But I doubt that Kinect will ever incorporate millimeter or back scatter sensors into the commercial versions.


Next

I know we’ve all seen Jack Dangermond’s “instrumented universe” prophecies, but another angle is remote dashboarding. Put the instrument controls right on the floor in front of us and abstract the sensored world one step further into the mirror. That way heavy equipment operators can get nice aerobic workouts too.


Next Step

Can’t miss the augmented reality angle. Pico projector in a phone ought to handle this trick in the handheld world.


and then UGV

Why not let that Rumba do some modeling?


or UAV

Add a bit of UAV and we can move mirror land from the 30cm (1 foot) resolution capture soon to be added to Bing Maps (see Blaise Aguera y Arcas comments) to hmmm what looks like sub centimeter. Do we doubt that the venerable licensed surveyor will eventually have one of these GatewingX100 thing-a-ma-bobs in his truck.

Summary

So we move along. I am seeing some sanity in the WP7 spanning XNA and Silverlight in the same mobile device. Convergence into the 3D mirror land will be less painful for those of us developing in the Microsoft framework. HTML5 is nice and I’m happy to see the rebirth of SVG, but then again, the world moves apace, and I look forward to some genuine 3D adventures in the next generation mirror land.

Route Optimization and Death of a Salesman

Taking an arbitrary list of addresses and finding an optimized route has been a pretty common problem ever since traveling salesmen. It has been the bane of many computer science students leading to more than a few minor tragedies, as well as Arthur Miller’s great American tragedy. Technically known as an np-complete problem, computational time escalates quickly and tragically as the number of stops increase.

Bing includes some valuable Routing services like routing with waypoints, traffic optimization, optimization of time or distance, or even walking routes versus driving versus major routes. However, there are some limitations to Bing Routing Service , and even Bing could not prevent Willy Loman’s tragic demise.

One limitation of Bing Routing is that the maximum number of waypoint stops is 25. This is probably not a notable issue for individual users, but it is a problem for enterprise use with large numbers of stops to calculate.

Perhaps a broader issue often encountered is waypoint or stop order. Bing Route service does not attempt to reorder waypoints for optimal routing. Route segments between waypoints are optimized, but waypoints themselves are up to the user. Often stop points are coming from a SharePoint list, a contact address book, an Excel spreadsheet, or a database without benefit of sort ordering based on route optimization. This is where route optimization comes in handy.

OnTerra Systems has been involved with Fleet management for some time now and recently introduced a RouteOptimization Service.

There are of course fairly complex algorithms involved and computational scientists have been at some pains to circumscribe the limits of the problem. One simplification that makes this much easier is to ignore routing momentarily and use a shortest distance algorithm to make a first route optimization pass. One way this can be accomplished is by looking at a set of connected nodes and determining segment intersects. By recursively re–ordering nodes to eliminate segment intersects, the computer quickly turns the above node set into this:

The nodes are first ordered with the simplified assumption of straight line segment connectors, and only after a re-ordering is the usual Bing Route service triggered to get actual routes between nodes. This is one of those algorithms that take some liberties to find a solution in real time i.e. time we can live with. It doesn’t guarantee “The Absolute Best” route, but a route that is “good enough” and in the vast majority of cases will in fact be the best, just not guaranteed.

Of course mathematicians and purists cringe at the idea, however, that is ordinarily what engineering is all about, getting an approximate solution in less than the time constraint of a useable solution.

OnTerra Systems has added some other refinements to the service with the help of Bing Maps Silverlight Control. This UI uses both Bing Geocoding as well as Bing Route services. In addition it makes use of the simplified RouteOptimization service to make the route UI shown above. Users can choose whether to optimize for time or distance. Minor modifications could use traffic optimization, available in Bing, just as well. However, traffic optimization requires a different license and a bit more money.

Entering points can be accomplished several ways, with a click approach, from manually entered addresses, or even more easily from an Excel spreadsheet of addresses. Route definition can be set for round trip, one way to a known end destination, or one way to whichever end is the most efficient.

This UI is only one of many that could be used. As a WCF Service, RouteOptimization can take latitude, longitude point sets from any source and return the ordered points for display in any web UI.

This example Silverlight UI is a three step process of service chaining. First points are collected from the user. If addresses are listed rather than latitude longitude points, then Bing Geocode Service is called to arrive at the necessary list of latitude, longitude points. These in turn are handed to the RouteOptimizer Service. The returned points are now ordered and can be given to the Bing Route Service in the 3rd step of a service chain. Finally the resulting route is plotted in the Silverlight map UI.

Waypoint limit work around:
An interesting side note to RouteOptimization Service is the ability to extend the number of waypoints. Microsoft’s restriction to 25 waypoints is probably a scaling throttle to prevent service users from sending in hundreds and possibly thousands of waypoints for a single route. The Route Service could be compromised with many large count waypoint requests.

However, with the ability to order waypoints with an outside service this limit has a work around. First run an optimization on all of the stops using RouteOptimizer service. Now simply loop through the return set with multiple calls to Bing Route in 25 node chunks. This simple divide and conquer achieves a simple work around to the Waypoint limitation. Note that the public sample here is also limited to 25 stops. To use this work-around, you’ll need a licensed version.

Alternate UIs
Of course UIs may multiply. Route Savvy is primarily a service to which any number of UIs can connect and Silverlight happens to be a nice way to create useful UIs. Perhaps a more convenient UI is the Bing Map Gallery version found at Bing Maps Explore:
Bing Map Explore Route Savvy.

Linda Loman and the Parent Car Pool:
Anyone out there with kids in sports has probably run into this traveling salesman problem. (Fast forward to 2010 and Linda Loman jumps in the van with Biff ) There are 6 kids in the car pool. What is the optimal route for picking up all kids and delivering them to the playing field on time? If you want to know, just fire up RouteOptimizer and give it a whirl.

Summary:
OnTerra Systems Route Optimization Service supplements the already valuable Bing Services by both optimizing input stop orders and extending the waypoint limitation. This is an illustration of the utility of web service chains. The ability to link many services into a solution chain is one of the dreams come true of web development and one reason why web applications continue to supersede the desktop world.

Please note, even though RouteOptimizer will help Linda Loman’s car pool run smoothly, it won’t prevent the death of a salesman. Sorry, only a higher plane optimization can do that.

Connecting the Data Dots – Hybrid Architecture

Web mapping has generally been a 3 tier proposition. In a typical small to medium scale scenario there will almost always be a data source residing in a spatial database, with some type of service in the middle relaying queries from a browser client UI to the database and back.

I’ve worked with all kinds of permutations of 3 tier web mapping, some easier to use than others. However, a few months ago I sat down with all the Microsoft offerings and worked out an example using SQL Server + WCF + Bing Maps Silverlight Control. Notice tools for all three tiers are available from the same vendor i.e. Microsoft Visual Studio. I have to admit that it is really nice to have integrated tools across the whole span. The Microsoft option has only been possible in the last year or so with the introduction of SQL Server 2008 and Bing Maps Silverlight Map control.

The resulting project is available on codeplex: dataconnector
and you can play with a version online here: DataConnectorUI

When working on the project, I was starting out in WCF with some reservations. SQL Spatial was similar to much of my earlier work with PostGIS. While Bing Maps Silverlight Control and XAML echoed work I’d done a decade back with SVG, just more so. However, for the middle tier I had generally used something from the OGC world such as GeoServer. Putting together my own middle tier service using WCF was largely experimental. WCF turned out to be less daunting than I had anticipated. In addition, it also afforded opportunity to try out a few different approaches for transferring spatial query results to the UI client.

There is more complete information on the project here:
http://dataconnector.codeplex.com/documentation

After all the experimental approaches my conclusion is that even with the powerful CLR performance of Silverlight Bing Maps Control, most scenarios still call for a hybrid approach: raster performance tile pyramids for large extent or dense data resources, and vectors for better user interaction at lower levels in the pyramid.

Tile Pyramids don’t have to be static and DataConnector has examples of both static and dynamic tile sources. The static example is a little different from other approaches I’ve used, such as GeoWebCache, since it drops tiles into SQL Server as they are created rather than using a file system pyramid. I imagine that a straight static file system source could be a bit faster, but it is nice to have indexed quadkey access and all data residing in a single repository. This was actually a better choice when deploying to Azure, since I didn’t have to work out a blob storage option for the tiles in addition to the already available SQL Azure.

Hybrid web mapping:

Here are some of the tradeoffs involved between vector and raster tiles.

Hybrid architectures switch between the two depending on the client’s position in the resource pyramid. Here is my analysis of feature count ranges and optimal architecture:

1. Low – For vector poly feature counts < 300 features per viewport, I’d use vector queries from DB. Taking advantage of the SQL Reduce function makes it possible to drop node counts for polygons and polylines for lower zoom levels. Points are more efficient and up to 3000-5000 points per viewport are still possible.

2. Medium – For zoomlevels with counts > 300 per viewport, I’d use a dynamic tile builder at the top of the pyramid. I’m not sure what the upper limit is on performance here. I’ve only run it on fairly small tables 2000 records. Eventually dynamic tile building on the server effects performance (at the server not the client).

3. High – For zoomlevels with high feature counts and large poly node counts, I’d start with pre-seeded static tile at low zoomlevels at the top of the pyramid, perhaps dynamic tiles in the middle pyramid, and vectors at the bottom.

4. Very High – For very high feature counts at low zoomlevels near the top of the pyramid I’d just turn off the layer. There probably isn’t much reason to show very dense resources until the user moves in to an area of interest. For dense point sources a heat map raster overview would be best at the top of the pyramid. At middle levels I’d use a caching tile builder with vectors again at higher zoom levels at the bottom of the pyramid.

Here is a graphic view of some hybrid architectural options:
DataConnector screen shotDataConnector screen shot

DataConnector screen shotDataConnector screen shot

Data Distribution Geographically:
Another consideration is the distribution of data in the resource. Homogenous geographic data density works best with hard zoom level switches. In other words, the switch from vector to raster tile can be coded to zoomlevel regardless of where the client has panned in the extent of the data. This is simple to implement.

However where data is relatively heterogeneous geographically it might be nice to arrange switching according to density. An example might be parcel data densities that vary across urban and rural areas. Instead of simple zoom levels, the switch between tile and vector is based on density calculations. Having available a heat map overview, for example, could provide a quick viewport density calculation based on a pixel sum of the heat map intersecting with the user’s viewport. This density calculation would be used for the switch rather than a simpler zoom level switch. This way rural area of interest can gain the benefit of vectors higher in the pyramid than would be useful in urban areas.

DataConnector screen shotDataConnector screen shot

Point Layers:
Points have a slightly different twist. For one thing too many points clutter a map, while their simplicity means that more point vectors can be rendered before affecting UI performance. Heat Maps are a great way to show density at higher levels in the pyramid. Heat Maps can be dynamic tile source or a more generalized caching tile pyramid. In a point layer scenario at some level there is a switch from Heat Map to Cluster Icons, and then to individual Pushpins. Using power scaling at pushpin levels allows higher density pins to show higher in the pyramid without as much clutter. Power scaling hooks the icon size for the pin to zoomlevel. Experiments showed icon max limit for Bing Silverlight Map Control at 3000-5000 per viewport.

DataConnector screen shot

Some Caveats:
Tile pyramids are of course most efficient when the data is relatively static. With highly dynamic data, tiles can be built on the fly but with consequent loss of performance as well as loading on the server that affects scaling. In an intermediate situation with data that changes slowly, static tiles are still an option using a pre-seeding batch process run at some scheduled interval.

Batch tile loading also has limitations for very dense resources that require tiling down deep in a pyramid where the number of tiles grows very large. Seeding all levels of a deep pyramid requires some time, perhaps too much time. However, in a hybrid case this should rarely happen since the bottom levels of the pyramid are handled dynamically as vectors.

It is also worth noting that with Silverlight the client hardware affects performance. Silverlight has an advantage for web distribution. It distributes the cpu load out to the clients harnessing all their resources. However, an ancient client with old hardware performance will not match performance of newer machines.

Conclusion:

A Hybrid zoom level based approach is the best general architecture for Silverlight web maps where large data sets are involved. Using your own service provides more options in architecting a web map solution.

Microsoft’s WCF is a nice framework especially since it leverages the same C# language, IDE, and debugging capabilities across all tiers of a solution. Microsoft is the only vendor out there with the breadth to give developers an integrated solution across the whole spectrum from UI graphics, to customizable services, to SQL spatial tables.

Then throw in global map and imagery resources from Bing, with Geocode, Routing, and Search services, along with the Azure cloud platform for scalability and it’s no wonder Microsoft is a hit with the enterprise. Microsoft’s full range single vendor package is obviously a powerful incentive in the enterprise world. Although relatively new to the game, Microsoft’s full court offense puts some pressure on traditional GIS vendors, especially in the web distribution side of the equation.