Vertical datum unavailable

[tylerbarnes]

I’m trying to set the reference system to NAD83 with NAVD88 as the vertical reference. The survey was completed with all systems in that reference frame: the Phantom 4 RTK drone and the rover used to collect GCP positions.

I have downloaded geoid 18, conterminous US, from the Agisoft geoid page and placed it in the geoids folder within the metashape package contents. Back in the application and under “Reference Settings”, I find a few options for NAD83 with NAVD88, but none of the EPSG codes match that of the geoid. Regardless, I select one of the NAD83 with NAVD88 options but then I get a message stating the “Selected vertical datum is unavailable. Please configure datum transformation.” Any ideas what is going on here? I’m not sure why the vertical datum is unavailable since the geoid is available.

[Paulo]

Hello tylerbarnes,

the longitude coordinates from downloaded  geoid18 file are in the 0 to 360 range instead of -180 to 180. Please look at following https://www.agisoft.com/forum/index.php?topic=14046.msg61886#msg61886 to see if new geoid18 link solves your problem...

For example, I loaded in Global Mapper the geoid18 Puerto Rico file and the shifted by -360 deg longitude file. It is clear that the original file is outside the world countries map...

[tylerbarnes]

Hi Paul,

Is it necessary for me to run the code you provide to define my Compound CS? I'm only familiar with interacting with metashape using the GUI.

I tried the protocol you outline in the post you reference, but it doesn't seem to accept the geoid I select (see attachment). Regardless of the geoid I select in step 3, it just reverts to a different option in step 4.

[Paulo]

Hi tyler,

i would copy the correctly shifted geoid 2018 file to your Agisoft geoids folder. And then you will not need to add the file in the datum parameters configuration. see attachment...However, remove from same folder  any previous noaa geoid files (like geoid 2012a or geoid 2012b). Since they are referred to same datum/height they will enter in conflict with 2018 file..it should do the trick

[tylerbarnes]

That seems to work!
Thanks Paulo!