Tuesday, September 29, 2009

LiDAR-derived contours are useful, too.

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


  1. Good point on the contours. At work we use a small contour interval (~5 ft or less) to improve our site mapping of paleoseismic sites, especially in low relief areas where hillshades offer less help.

  2. Yes...currently trying it on the dry bed of Walker Lake where the river has dumped a bunch of deltas and left some bizarre patterns. The relief is so low that a 1-m contour interval is only slightly useful.


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