Can Image Server mosaic LIDAR data?

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04-29-2010 05:45 AM
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KristenDavis
New Contributor
Hi,

Does Image Server support the LIDAR data format? If so, can it dynamically mosaic the tiles?

Thanks!
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10 Replies
TheresaValentine
New Contributor II
I'm just been trying to load a bare earth dem into image server, but looks like I have to convert my arc grids into ascii or some other format before they will load.  Rather annoying...
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PeterBecker
Esri Regular Contributor
Direct lidar sources (such as LAS) can not currently be directly handled. (yet)
Rasterized lidar elevation data can be served. The methodology is to create a Elevation based Images Service Definition and then serve this. A number of different formats are supported as part of the Elevation raster types and they system will mosaic the elevation together that can be in different format and projections. A presentation on this was given at FedUC in Feb 2010 (see http://proceedings.esri.com/library/userconf/feduc10/papers/tech/feduc2010_image_services_for_elevat...) (It appears that this file is currently broken. I sill check and get it repaired.) The big advantage to serving elevation as image services is that you can create an elevation service that dynamically mosaics a lot of different sources together. Eg GTOPO + SRTM + NED + rasterized lidar
Concerning the format of the data. Although GRID can be used as a source, I would recommend were possible converting to 32bit float TIF with LZW compression.. There can be issues in serving GRID files higher capacity servers. TIF works well. ASCII DEMs would work, but I don't recommend as they are very large and slow to read. The main issue in 9.3 with such elevation data is handling nodata areas. These are best handled by redefining the footprint of the rasters to exclude NoData area. Support for data with NoData is improved significantly at V10.
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TheresaValentine
New Contributor II
I did get my service to work, after a lot of help.  The problem now is that I have one area that is showing up as no-data and while I have the data in the directory, I can't figure out why this one area is showing up as totally black in my preview and when I make a service

a service I made is here:  add the service in arccatalog:  meridian.forestry.oregonstate.edu/Arcgis/Services/willamette
the service is called will_be  and the error is in the lower right (east) part of the where there is an elbow of sorts...
it shows up pretty well on the will_shade service  (only part that is flat in the mountains...)
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PeterTimmers
Occasional Contributor III
We've got plenty of elevation service issues. 

Most of our data is coming as LAS files.

We've also got data in ascii dems that has both nodata and -9999 as no data in irregular shapes.  (Is there a way to reshape the footprint automatically for elevation data?)

When trying to use such files in something like ArcGIS Explorer as an elevation source it makes for some wild countryside.

Looking forward to 10.
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PeterBecker
Esri Regular Contributor
I'm not sure why the one area is coming up black. Please check the raster by adding it directly in ArcMap. Is it possible that it needs to be scaled?
Yes you can get the system to exclude the NoData areas by redefining the footprints to exclude these areas. Use the recompute footprint by Radiometery function. You will need to set the number of vertices to something like 50 for these shapes. For elevation data is so  sometime better to use a service process to classify the imagery into two colors, compute the footprint and then remove the classification process. This will not remove holes though. In some cases is it better to edit the edges or you may have a shape with the geometry and you can use recompute footprint by related geometry. V10 has much better support for NoData areas.
For the data that you have that is ASCII DEM I would recommend you convert this to TIF wtih LZW compression. It will be much smaller and faster.
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TheresaValentine
New Contributor II
I've checked the raster, and it looks good when I add it directly into arcmap.  I've tried just about everything I know...
I've put all the rasters in one directory (so no overlaps)... I've rebuilt statistics on the one raster... It keeps showing up black.
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PeterTimmers
Occasional Contributor III
Trying converting that one tile to a different format using either Arcmap or GDAL.   That will either show up the problems (sometimes) or make a tile that works.
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PeterBecker
Esri Regular Contributor
Check the properties of the raster that comes up black in comparion with the other rasters. There is a recent seperate review on a possible issue between some files that are MSBFirst vs LSBFirst. Some of the format readers can get this wrong. As timmerspk  mentions, try converting that one file if necessary.
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PeterTimmers
Occasional Contributor III
Back to the original question...

Just want to check whether mosaiking of LIDAR has become possible in 10 or not?

I can't seem to find anyway of doing it.
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