okansas.blogspot.com Occassional thoughts about orienteering |
Saturday, February 25, 2012 Lidar data for vegetation mappingI've written about my experiments in using lidar data and OL Laser to generate rough maps of runnability. Here is a screen cast that demonstrates how I create the images.Back to okansas.blogspot.com. posted by Michael | 10:32 AM
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I am preparing base maps for a huge area in the mountains of Telemark, Norway. (About 115 km^2)
The main problem with OL Laser for such a big area is that the source data consists of 67 separate LAS files, so it takes days to process them all manually. :-( (I am talking to the OL Laser author about adding a batch mode, and/or a command line interface.) Yesterday I used the open source LAStools utilities to process all the files at once, first generating a vegetation height map, then converting that to a grey-scale image (130 Mpixel!) image. I then used Photoshop (but many other programs would have done the same job) to first convert the grey scale image to an indexed format, then replaced the palette with a custom set similar to your setup, mapping various heights to different (mostly) green colors, before converting back to RGB jpeg. Total processing time was less than 30 min, with only 5 min of manual adjustments. Now I want to look into a more intelligent conversion process, looking not just at maximum canopy height but also the density of any intermediate returns (between ground and first return).
Hi,
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nice instructive demo. Would be cool if you could do a similar analysis with LAStools. Check this powerpoint presentation for some guidance: http://lastools.org/download/lastools.ppt Cheers, Martin @lastools |
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