Display of Coastal Lidar Grids

Older coastal lidar, with sparser point densities, can present challenges for display.  You might consider void filling, and the display options you want.

2004 Pre-Ivan survey Elevation map--relatively tolerant of voids Reflectance map or Hillshade--not very tolerant of voids.

Computing requires all the point's neighbors (Focal operation).

If any neighbors are missing, the point will be missing.

Data as downloaded
Data after void filling

 

Reflectance map with blue/green color scheme for points below and above sea level. 
Note the wave crestsf in green on the right of the map.
Elevation map with land/sea color scheme.


Difference map between two surveys, shown as Elevation map.  The color scheme only shows elevation differences with an absolute value less than 2 m.  The data has big vertical differences (up to 30m) which are probably not significant or meaningful, especially for natural processes like beach erosion and deposition.  Restricting the range of values used for coloring may enhance the ability to see the trends of interest.  In this map, note that the largest positive changes are along the edges of the pier and some of the buildings; other large changes relate to the vegetation, which can grow rapidly, and can respond very different in leaf-on and leaf-off conditions.

In coastal regions, the largest changes are likely be be in the dune-berm region, reflecting both seasonal and long term changes.

Last revision 8/5/2018