okansas.blogspot.com
Occassional thoughts about orienteering


Saturday, February 25, 2012

Lidar data for vegetation mapping

 

I'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.



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posted by Michael | 10:32 AM

4 comments


Comments:
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).
 
I wish I had the trouble of dealing with 115 Km^2 of orienteering terrain!

Michael
 
very good video.
thank you very much!
 
Hi,

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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