Here comes the LiDAR!


QCoherent LiDAR Server
Fig 1 – LiDAR Server in Silverlight MapControl

Online LiDAR is reaching critical mass and there are a lot of interesting projects.

PAMAP is one example with LiDAR covering all of Western Pennsylvania, which due to the Alleghenies, has a good deal of interesting topography at 3.2 ft resolution. Unfortunately, the Get Capabilities shows that this is another of those no spherical mercator, EPSG:3857, WMS services. Meaning the image doesn’t line up with underlying web map services.

PAMAP LiDAR in Silverlight View
Fig 2 – PAMAP LiDAR WMS

The GEON website is another LiDAR project offering access to LiDAR sets via opentopography.org or OpenTopography Portal

Here is a view of a GeoEarthScope ISB LiDAR 0.5 m data set shown on GoogleEarth

GoogleEarth LiDAR
Fig 3 – GoogleEarth view of OpenTopography ISB LiDAR data (unfiltered)

In addition to providing raw data and GoogleEarth kml views, GEON has received NSF ClueE funding for a Cloud based service:

On Demand LiDAR
“The project will study dynamic strategies for provisioning such applications by doing a performance evaluation of alternative strategies for serving very large data sets. The cloud platforms that will be used in the project will be the Google-IBM CluE cluster and the HP-Intel-Yahoo cluster, both of which have been assembled in collaboration with NSF for cloud computing research. The LiDAR processing application hosted at the OpenTopography portal has been selected as the representative application for this study. The application allows users to (i) subset remote sensing data (stored as point cloud data sets), (ii) process it using different algorithms, and (iii) visualize the output. The project will study alternative implementations for each stepusing database technology as well as Hadoop (www.hadoop.org) and run a series of performance evaluation experiments. Cloud platforms with thousands of processors and access to hundreds of terabytes of storage provide a natural environment for implementing OpenTopography processing routines, which are highly data-parallel in nature.”

Looks like they hit all the sweet spots. Of course you don’t need to have access to specialized NSF funded Google-IBM CluE clusters to play. Amazon’s Elastic MapReduce lets ‘poor folk’ have a crack at Hadoop playgounds too.

On a less esoteric note, I pointed my new Silverlight MapControl CTP WMS viewer at a LiDAR Server project by QCoherent. QCoherent is nearly a neighbor with their office down the street a mile or two from me here in Colorado. I don’t really use their LiDAR software (I’m the online only sort), but I was fascinated to learn that they have a new LiDAR Server for providing WMS access to LiDAR data.

LiDAR Server is a WMS middle tier server that provides online access to LiDAR datasets with on the fly styling, tinning, and contouring.

  • WMS compliant map server
  • Multiple representations of LiDAR data: points, TIN, contours, etc.
  • Unique layers for each representation
  • Multiple ways of filtering and colorizing data (implemented through styles in the WMS)
  • High performance on-the-fly tinning engine
  • High performance on-the-fly contouring engine

It wasn’t much of a stretch to add a few of LiDAR Server sample urls to my Silverlight viewer and go exploring. The WMS is 1.3.0 compliant and does publish EPSG:3785 (now deprecated in favor of EPSG:3857), so Virtual Earth alignment is possible. Basically the GetCapabilities exposes four layers – Boundaries, Points, Contours, and TIN. Each of these layers has a series of selectable styles such as All or Ground Elevation, Classification, Intensity, and Return which are simply preset style coloring. The layers are queryable which means GetFeatureInfo requests are active.

Here are some examples using the Silverlight WMS Viewer:

LiDAR Server
Fig 4 – LiDAR Server Vancouver TIN AllElevation Building Footprints

I’ve turned down opacity slightly so the Aerial MapMode can just be seen beneath. Its interesting to note the footprint against the aerial imagery and see how well orthrectification worked, or not. Tough in the middle of hirise towers. Dark blue is Elevation (Z): -14.01

LiDAR Server
Fig 5 – LiDAR Server Vancouver TIN AllElevation Building Footprints + Contours

LiDAR Server
Fig 6 – LiDAR Server Cumberland TIN GroundElevation – Bare Earth

LiDAR Server
Fig 7 – LiDAR Server Cumberland TIN AllClassification

LiDAR Server
Fig 8 – LiDAR Server Cumberland Contour AutoGround

Note that all the heavy lifting is done by LiDAR Server. The Silverlight Viewer merely takes advantage of the exposed WMS service to show various sets of layers over Virtual Earth base. When I get around to it I’ll be adding other base as well: OSM, Yahoo, OpenAerial etc. I was surprised at the speed of the ‘on the fly’ TIN and contouring capability. The OpenGL 1.3 capable video card requirement prohibits use in an Amazon Cloud sense, since EC2 instances are all headless, i.e. graphic cards not expected anytime soon.

LiDAR is obviously a 3D oriented resource and at present Silverlight is 2D only. Too bad. Although there is a 2.5D capability in Silverlight 3.0 beta that lets a MapControl surface be twisted out of screen plane, this doesn’t help much with topography explorations. Since the Javascript VE SDK does allow a 3D mode it could drape images over terrain just like GoogleEarth. I assume Silverlight is headed toward 3D like WPF, but I’m just speculating. If any Microsoftee reads this please put in a good word for 3D Silverlight real soon now.

Keep in mind, however, that the actual WMS output is imagery, png or jpg, not mesh. In the GoogleEarth kml example the LiDAR is ground clamped <GroundOverlay> png images. In other words all the increased clarity of 0.5m resolution LiDAR is an illusion based on shaded imagery draped over existing Google terrain at whatever resolution it maintains. Of course Google and Microsoft are in a race to provide the highest resolution DEM available so it is possible 1m PAMAP is already included.

I’m sure there are other significant online LiDAR projects out there, and I haven’t even looked at BIM LiDAR which is heating up as well.

Summary
Looking forward to national submeter coverage!

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