HELP :compound coodinate system

[nachogi73]

Hi:
I am trying to create a "compound coordinate system," that is, by adding a reference geoid or "vertical coordinate system."

We tried to create a user-defined coordinate system but failed.

I need to create a compound system with UTM31 ETRS89 (EPSG 25831) and  EGM08 rednap geoid, they are reference systems in Spain.

It could also be a system composed of EPSG 25831 and the EGM2008 geoid.

Anyone know how to create it in Metashape?

I saw the possibility of importing a file type * .prj into metashape:

Anyone know with what tool you can create the prj file to import?

Thank you

[Alexey Pasumansky]

Hello nachogi73,

Have you checked the following instructions:
https://agisoft.freshdesk.com/support/solutions/articles/31000148332-how-to-use-height-above-geoid-for-the-coordinate-system

They should help, if you have an undulation grid file for Rednap geoid.

[nachogi73]

Hi again:

I find this guide yesterday. It works!!!

https://agisoft.freshdesk.com/support/solutions/articles/31000148332-how-to-use-height-above-geoid-for-the-coordinate-system

Thank you very much....!!


greetings and congratulations on your work

[nachogi73]

Hi again

We tried to create the conpound cordinate system. It seems to be right and it works, but we have a little difference.

In the past we worked with GPCS on the ground measured with survey GPS device (accuracy XY=0.01 and Z=0.02).

So that, with the new Phantom 4 RTK and the conpund coordinate system, we achieve a very good XY accuracy BUT in Z coordinate we had a difference betwen our GPS Z and the estimate Z in metashape.

This difference it can be abot 2 meters to 5. It is excatly the same difference for one chunk, I mean: we measure 3-4 GPCs in early works (just to check) and all of them had the same "offset".

We think that It can be because our conpound coordinate system.

Question: if I upload the Geoid (in spain REDNAP-egm08) and with EPSG25830 and EPSG 25831...would you please create this conpund coordinate system for us?

Thanks in advance.