Export DEM .TIFF Z problem.

[Joel Cast]

Hi,

Can someone explain to me why the altitudes of my DEM or Ortho file no longer correspond after I export it as a .tiff file? In my project (see screenshot), I have a terrain with a GCP #1 altitude of 222.868 m. However, once I export the .tiff file and open it in the viewer, the altitude at the location of my GCP #1 is displayed as 207.600 m when I use the ruler tool. This means there is a difference of 15.268 meters. I am not sure what I am doing wrong. Can someone help me ensure that the .tiff file I give to the client has the correct elevations?

Thank

[Alexey Pasumansky]

Hello Joel,

Can you please check (with the Ruler tool) the coordinate value corresponding to marker "1" location on the orthomosaic/DEM (in Ortho view) and also specify the coordinate system in which DEM has been generated?

Also please specify, if the same coordinate system has been selected for Export DEM operation.

I think that the confusion is related to the fact that Agisoft Viewer uses WGS84 coordinate system for the georeferenced data display, so the coordinates (including the altitude) may differ, if the original coordinate system for the given asset is based on non-WGS84 datum.

[Joel Cast]

Hello Alexey, I finally found the solution to my problem. 1 - Import t tiled model  2 - Import DEM, then orthomosaic. The reverse doesn't work. All coordinate is in  NAD8383 (csrs) mtm zone 7 with the correct Z.
if your dont import a tiled model or normal model before, the Z will be wrong.

Cheers