Using RTK and Ground control Points

[Mdaemon]

Hello Together,

I am using Metashape since 2015 for surveying of quarries. I love the programm, the results are very good.
Usually I use a Phantom 4 Pro and a lot of ground control points (up to 3-4 / 10.000 m²). GCPs are measured with Trimble R6.

Now i have bought a Mavic 3 Enterprise, using also the RTK Modul (using Network). I works well, BUT:

Total accuracy is lower than using just the P4P. This is, because Trimble R6 is using a local ajustment to the austrian reference system (which is not available to the MAVIC).

Total error is about 0,08 cm, which is not so much but gives huge deviations in VolumeCalculation.

Now the question: How can I decide, using the "location of the fotos or not?"

Thx,

Martin

[Mdaemon]

Hello,

I have found the item in the general settings. No caculating again, will see.

regards
Martin

[olihar]

Project the photos from the drone to the GEOid you are using.

[Corensia]

As Olihar said, if the GCP measurements from the Trimble R6 are geoid altitudes make sure it is properly designated in Metashape as well. Otherwise Metashape defaults to using the GCP as if ellipsoid altitudes are used resulting in an increased error. You can use this link as reference for applying geoid altitudes : https://agisoft.freshdesk.com/support/solutions/articles/31000148332-how-to-use-height-above-geoid-for-the-coordinate-system

However, I found it easier to get the WGS84 readings with ellipsoid altitude from the Trimble device (which is the same CRS as the M3E), process the data, and then convert to my local adjusted geoid CRS only when exporting my results.

Hope that helps!