LAS file prep, create grids

 

If you do not set these values correctly, the color scale in your grid could be off.  Low noise will mean very few points on the low end of the color scheme, and high noise will mean very few points on the high end.  The net effect will be to squeeze all the elevation colors into a narrow central range.  You can get around this by using the percentile option for the color scale (z Range, Percentiles).

 Grid will be computed with the same size and grid spacing as the DEM opened to get the point cloud display.  These might approximate a DSM and DTM, if there are multiple returns in each pixel.  If there is only one return per pixel, these will be identical.

For the ceiling, each point in the point cloud will be placed at the nearest grid node, and the highest value retained.  This might approximate a DSM.

This is elevation coloring; the holes will make reflectance maps problematical.  It might be a good idea to use a larger grid spacing, or try to interpolate across the voids.
For the floor, each point in the point cloud will be placed at the nearest grid node, and the lowest value retained.  This might approximate a DTM.  You need a grid size that is large enough that there are multiple returns in each grid cell, and one of them must have gotten to the ground.

 


Last revision 2/10/2018