Point Cloud Draw Tab

LIDAR Point cloud form  option,  Draw tab





Thin, map: faster if you skip points

LAS auto thin: the program can attempt smart thinning that will speed up drawing and not create holes.

Thin coeffiecient: with auto thinninng, the value will be PointDensity * ScreenPixelSize * ThinCoefficient

LAS legend

Scale 1%-99%: by ignoring the extremes tails of the elevation distribution you can avoid bird strikes and other anomalies.

 

IHS color merge: shows point cloud as overlay with the base map showing through.

Opacity: set level

 

Min and Max Z: the program will attempt to scale the elevation colors, but you can force the extremes to use.  Use the Scale 1%-99% as the first step.  You may need to look at a histogram (stats tab) to decide what are the real limits of the data; birds can give anomalous high points and there can also be low points from reflected returns which take too long and are placed underground.

  • Cloud Z returns to  the extremes in the point cloud.
  • DEM Z takes the extremes in the DEM used in the base map.  There are good reasons why you will have valid returns higher than the DEM (buildings, trees, power lines), but you can decide what would be excessive and there are probably not much higher than the mountain tops.

Coloring: both the intensity and RGB values are 16 bits in the LAS file, and supposed to be scaled to use the full dynamic range (so that a division by 256 would lead to reasonable coloring).  This is frequently not the the case.  You can set the min and max colors, complete black and white respectively, and the program will linearly scale between them.  To find out the range of values in the LAS file, and hints at extreme tail values, use Histograms/Counts on the Stats tab.  Intensity is now done separately for each cloud.


Main controls on the bottom of the form, always visible:


Last revision 6/16/2020