I have two sets of LiDAR for the same region that I would like to compare. Both are in NAVD88. The older LiDAR set used GEOID03 for the transformation. The newer LiDAR set used GEOID09 for the transformation.
To accurately compare these two LiDAR datasets do I need to update the old dataset to use the new geoid?
The following ngs.noaa.gov link is relevant, but it is still a little unclear to me because in the first sentence it says use GEOID03 if it is from 2003, and then, goes on to say GEOID09 will be more accurate for data use. The gist sounds like that it should be converted to the same geoid. That is in line with my original thinking that it is a systematic error that should be corrected. I was hoping there would be someone out there that had experience with geoid transformations to confirm as it seems like it might add additional uncertainty.
GEOID03 was fit to the data available in 2003. If you are still using data from 2003, the GEOID03 will fit better. However, NGS has changed the heights in the database for many of these points. Hence, GEOID03 will no longer fit the current values to (in some cases) better than the dm-level. GEOID09 was developed using current values. Hence, GEOID09 should be used now if you want to get results consistent with those showing on the NGS datasheets (our current best estimate of actual heights).