Hi, I've got problem with coordinate system (Kertau RSO: EPSG 3168). The potential position (yellow icon) is far away (approx 50 meters) from actual coordinates (blue icon) on ground.
It also happen for coordinate system GDM2000 / Selangor Grid (EPSG:3380).
Anyone can help me for this?
I used DJI Phantom 4 Pro for mapping, i dont think it GPS fault, maybe the conversion between local coordinate and WGS84 got problems.
Phantom Pro is lying about GPS altitude. In photo EXIF tags there are no GPS altitudes only barometric altitudes. You can check with exiftool. Rename "exiftool.exe" to "exiftool(-k -a -u -F -n).exe" and check any JPG from P4P you will see that "Absolute altitude" is exactly the same as GPS altitude but it is impossible as absolute altitude comes from absolute barometric pressure and can't align so well. DJI doesn't write GPS altitude for non-RTK Phantoms because it is too innacurate and can change between flights too much.
Flight logs contain real gps values which you can check using log viewer( https://www.phantomhelp.com/LogViewer/Upload/) and export to kml or csv.
Your best option is to adjust altitudes before aerotriangulation. Unfortunately Bentley doesn't try to add any better support for DJI products to correct such issues as it is done by Agisoft or Pix4D.
Hi Oto,
Refer to the picture above, the distance to the input position is around 118 to 184 meters. I took a photo using DJI Phantom 4 Pro V2, I imported GCP in SRS code EPSG:3168. It is the same thing as above. I think it is not a problem from a DJI device.
Indeed it looks like it is horizontal shift. Maybe this is issue epsg:3168 "Adopts metric conversion of 0.914398 metres per yard exactly. "
You should contact Bentley to investigate. Is there a shift if using WGS84 coordinates? Does Malaya use GPS shift like China does?
It only happens when I use Malayan projections RSO and GDM2009.
It doesn’t happen when I use it in Cassini projections for every month.