accuracy of a models cooridantes in greek grid

General Feedback & Requests
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Hi. I ve been using reality capture for a brief time and i am exited with the programs capabilities. I use an RTK drone to create models and orthophotos. I am based in greece.

When i create a model, with the drones rtk measurements and then i check my orthos with my gcp’s measured with an rtk gps, but not used in the solution, i find significant differences.

when i use only the gcp’s coordinates to create the model all is ok. But u cannot always do that.

So i would like to have any suggestions in what am i doing wrong?

Also i have to mention that in order to have accuracy in the models coordinates, GPS data need to be transformed from wgs84 to greek grid (EGSA87) and then to Hellenic positioning system (Htrs07). coord sys. So we have 3 different datums with a main problem to solve, that there is a difference between orthometric heights and ellipsoid heights due to the use of different reference geoids. In order to solve this problem there is an unofficial tool the hepos transformation tool provided by the company that runs the greek cadaster.

let’s say that i find a solution for everything, i then need to change the mrk. file of the drones measurements, import it to the program and redo the process.

can i do that and how?

2

Hello Lampros,
how big differences are there? In which axis?
RealityCapture uses only ellipsoidal heights, so this could be the first part of your problem.
The GCPs are in Greek coordinate system?
Also, what are your alignment settings? Are you considering the RTK precision in the computation? And for such data it is good to know the camera’s calibration parameters. That could help to input them directly into computation.
It is not possible to import MRK file into RealityCapture directly, but you can use the part of it as a flight log. Just create a TXT file with the image names, coordinates and if you want, you can also use precisions (Change the coordinates of the photos - #11 by geoanture86).