Sunday, February 9, 2014

Weetamoo Woods in LIDAR

     Fusion is  handy software for processing  LIDAR data to separate out ground surface and vegetation layers.  However, it was written to prepare ground surface files for use in GIS programs.  As I mentioned in the last post about LIDAR (2/1/2014), one of the drawbacks of working  with Fusion is that only small surface areas may be sampled for 3D visualization.  The resolution can be impressive, but the LDV viewer does not allow for scanning of larger areas.  Recently, I downloaded Grass GIS, started reading "GIS for Dummies" (no kidding), and followed the instructions in the Fusion tutorial and Grass GIS wiki. Here are the results.
     This is the  LIDAR intensity image of Weetamoo Woods in Tiverton, RI.

This shows the footprint of the LIDAR raw data file downloaded from the USGS. Houses are visible to the right, and a stream runs south from the swamp at the north.  Below is the Fusion LDV showing a small farm which I knew to be there.

This area is to the bottom right of the intensity image.   The whole ground surface DTM file was converted to ASCII and imported into Grass GIS.  Here it is displayed in  garishly colored 3D.

The houses along the road show up clearly to the upper right. Lafayette Road is a narrow depression  running diagonally across the upper half of the area. It shows up better in my monitor, but I see two sets of walls.

The one at lower right is the same as that shown above in the Fusion LDV.  The one towards the top is a group of walls just south of Lafayette Road.   This corresponds to my GPS map.

The old farm is at waypoint 1458, and the other group of walls is visible as the blue dots just south of Lafayette Road, including waypoint 1296. There is supposed to be a way to enter GPS waypoints into these GIS projects, and to extract coordinates.  That is another chapter in the "Dummies" book...

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