Given that OCAD (and often my coding platform of choice, R), need to be explicitly told the projection of an incoming LiDAR file in the form of an EPSG code, and having found that the metadata for USGS TNM-sourced LiDAR is at best difficult to match to an EPSG code, and at worst, woefully incomplete, I've always found figuring out what the EPSG code for a given LiDAR file is to be a bit of a challenge.
The good folks at the USGS got tired of me asking them to confirm the EPSG code for a given LiDAR file and sent me a link to a .gpkg file bearing a layer with an attribute table that maps every LIDAR project name, aka 'work unit' to a (horizontal) EPSG code. The .gpkg file can be found here: https://prd-tnm.s3.amazonaws.com/StagedProducts/El...
. The LiDAR Project Name/work unit is part of the name of every USGS TNM LiDAR file.
If you don't want to mess with the .gpkg file, I've posted an excerpted Excel version (temporarily) here: https://1drv.ms/x/s!AmMT5E-2wBxLhyVDorP1Gh4l7kN8?e...
PS: the USGS also confirmed that "All the NAIP imagery served by The National Map is EPSG Code 3857 (Web Mercator)." *
Could be that those whose attention will be drawn to this post already know this... :-)
* Take that confirmation about all NAIP imagery being in EPSG:3857 with a grain of salt. There is at least some TNM/NAIP imagery in the Denver area (file: m_3910418_sw_13_1_20150910_20151102) that I am quite certain is in EPSG:26913.