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Sure, I have gone on and on about the amazing visualizations you can get with some tweaking of LiDAR data; however, it turns out that a pretty basic representation is also quite useful…contours. Yes, contours. Sometimes smaller scale features remain somewhat ambiguous in hillshades or slopeshades, but high-res, short interval contours from the LiDAR data can eliminate most of the ambiguity. In this case, it is a tiny area that I have struggled with on the Owyhee River. Here, a large landslide entered from the north, shoved the river channel to the south, and the river eventually worked its way back to the north to some extent. The array of surficial deposits in the void that comprises the right hand side of the image south of the river record this sequence of events as well as subsequent sedimentation by tributary fans. The contours really highlight the fans, and in conjunction with discernible drainage patterns evident in the LiDAR, it is clear what is fan and what is river, right?

2-m Contours were generated in GlobalMapper and exported as shapefile to view in Arc.
Note, Ian Madin (at DOGAMI) gave me the tip on contours especially as they relate to resolving fan features. He was right…it works!

Posted via email from Fresh Geologic Froth

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2 Comments

  1. indeed …. contour lines rock.

    when you have billions of LIDAR points i encourage you to try out my streaming pipeline to generate contours.

    i just helped a guy from norway to get contours for oslo from 757,322,873 points that were stored in 2,000 LAS files.

    but you must be willing to work in the windows commandline, which usually scares away some people. (-:

    the pipeline you will run will look something like this:

    spfinalize -i input_files.txt -lof -ilas -level 9 -ospb |
    spdelaunay2d -ispb -osmb | tin2iso -ismb -range 0 1000 5 -oslb | slclean -islb -oslb -length 5 | slsimp -islb -oslb -area 0.7 | sl2sl -islb -okml -tiling_nllsxy oslo_contours 352000 642800 2000 10 8 -utm 32N -ellipsoid 23

    • Martin, Thanks for the comment. You are miles beyond me in the LiDAR realm! I plan to explore your tools and see if I can figure them out…they appear to be very useful. And, yes, command line makes me wince.


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