Analysis of LiDAR shot densities for NCALM Eastern California Shear Zone (ECSZ) survey and B4

by Ramón Arrowsmith, December 2007

How does the shot density for a more typical NCALM survey in the desert, such as the one done for Dr. Mike Oskin at UNC, compare to the Southern San Andreas Laser scan ("B4") project data?

I did two runs in the OpenTopography Portal (LiDAR point cloud and custom DEMs), one for Helendale area in the Mojave Desert (Eastern California Shear Zone), and one for the area of Durmid Hill along the San Andreas Fault (B4). I produced DEMs using the local binning method with a 1 m DEM and a 1 m search radius. I computed the shot density per square meter by dividing the shot count from the 1 m search radius by its area (3.14 m²). It looks like the shot densities are nearly twice as high for the B4 (1 versus about 1.5 shots per square meter per swath).

ECSZ near Helendale

Here are the metadata for the GLW run: metadata1198004737276912750979.html.
PDF maps of GLW output
Helendale 1 m DEM with 1 m search radius overview
Helendale 1 m DEM with 1 m search radius zoom
Helendale 1 m DEM with 1 m search radius Shot DENSITY with profile. The single swath (yellow) has about 1 shot per square meter and the overlaps are up to about 2.5. I think there may be an elevation dependent increase in density (SW part of the area is higher and so are the densities). The densities also generally decrease broadly going down in elevation to the NE.
Helendale 1 m DEM with 1 m search radius Shot DENSITY with profile

SAF near Durmid Hill (B4)

Here are the metadata for the GLW run: metadata119800491080520078597.html.
PDF maps of GLW output
Durmid Hill 1 m DEM with 1 m search radius overview
Durmid Hill/Salt Creek 1 m DEM with 1 m search radius zoom
Durmid Hill/Salt Creek 1 m DEM with 1 m search radius Shot DENSITY with profile. Single swath is only about 1.5 to 2 shots per square meter. Double overlaps are 3-4. The data seem to be somewhat better behaved than the ECSZ data, but not a lot better.
Durmid Hill 1 m DEM with 1 m search radius Shot DENSITY with profile