Geoid Definition in Agisoft Metashape

[@UttrakhandiBhula]

sir, how should i know which geoid file supports in my region please revert

[@martinkiskemper1395]

Hello. In most cases you'll find this information on the website of your lokal surveying authority. You can also use global geoid files (EGM96, better EGM2020), but they are less acurate (~1m).

[@יובלמיכלסון]

Hi, thank you for the video. Why is the elevation of the GCP is different from the elevation of the photos even after you change it to geoid? Thank in advance

[@martinkiskemper1395]

The coordinates and heights of the photos are defined on the the WGS84-ellipsoid, so they are ellipsoidical heights. When converting to ETRS89-UTM with GCG2016 undulation the heights of the photos will shifted from ellipsoid to geoid. (Here in this region about 38m.)

[@רעותמיכלסון]

@@martinkiskemper1395 I appreciate your help

[@יובלמיכלסון]

@@martinkiskemper1395 Is it necessary that the GCP and the photo will be in the same coordinate system in order to optimize the photo of the drone ?

[@martinkiskemper1395]

@@יובלמיכלסון I think, it is not necessary, because the transformation parameters are known, but I always do it to easily check the flight altitude. And it is just one click. Optimizing the camera will calculate the camera parameters, like focal length, coordinates of center pixel and distortion correction parameters.

[@יובלמיכלסון]

@@martinkiskemper1395 got it.thank you for your help

[@UttrakhandiBhula]

since last 3 months i tried to process some drone data and always getting the deviation between the actual marker location and where it falls i checked all over in google and you tube but not find any solution your video gives me a hope of light please help sir

[@CR3DT]

Very good video, I noticed that you are setting the "reference photos" coordinate system to WGS88 even though you were using RTK. Why not set it to your local coordinate system?

[@martinkiskemper1395]

Coordinate system in the EXIF header of the photos is WGS84. So you have to set it to WGS84 in the project properties first. But in a next step you can convert them to a lokal coordinate system, normally to the project coordinate system (in my case ETRS89, UTM33 with GCG2016 Geoid).

[@CR3DT]

@@martinkiskemper1395 what your RTK network giving you corrections in WSG84?

[@_betoplus]

Ich werd hier noch irre. Ohne die Geoid Datei sind meine Punkte ca. 45m höher. Mit der Installation der geoiddatei sind sie nun 52 m zu weit unten. Ich weiß nicht mehr weiter 😞

[@shiezz]

After the geoid file was installed and the conversion was made, the height then will be in geoid height or orthometric height? I am interested to obtain DEM in orthometric height.

[@Little_geo_Wing]

+1

[@arnaudlrc]

Hi, how did you choose the 0.02cm accuracy? What device are you using for measuring GCPs? I have the Emlid RS2+. Do you know what accuracy this device has? Thanks in advance

[@martinkiskemper1395]

Accuracy is 0.02m (not 0.02cm). I use a Leica GS15 or Trimble R12i with SAPOS reference station service. I think with the Emlid RS2+ in combiantion with SAPOS or another reference station service it is also possible to get the same accuracy.