Servers by jDrones

Cam Message Geotag position error


(keeyen) #1

I try to geotag with CAM Message Synchro. While it successfully geotag all the images but when I process the data with Agisoft, The process reports show large X and Y error up to 80 meters. I compare the result with time offset method, the result is much accurate with an error of X and Y below 10 meters.
I try to adjust the shuttle lag but even input with 1 ms it refuses to process. I try to compare the result of Cam Message geotag images and time offset geotag images. It seems that in the initial stage, both Cam Message and Time offset show similar location. But after about a minutes or so, the location start to drift apart and after about 5 minutes, the distance difference can go up to 30 meters.
Simply said, the Cam Message method geotagged images will produce inaccurate geolocation and when processed with Agisoft, the orthomosaic will not able to align with Google map.
Does anyone having similar issue?


(Fi156) #2

I noticed something like that a month ago and tested today with a recent dataset and the following setup:

  • GCPs measured with L1/L2 GNSS.
  • File with CAM messages of camera positions from standard Ublox M8N chip on the drone.
  • File with backward calculated camera positions through SFM software from the GCP positions.

Project was aligned without any reference data, than GCPs where added.

CAM coordinates are within a 3 meter boundary of backward calculated positions over the whole flight.
This is mostly a systematic error, because GCPs where measured in specific local CRS and not WGS84…

TL;DR: Cant confirm with MP 1.3.57


(keeyen) #3

I try Pix4D and it Geotag accurately. I think it may be a Mission Planner issue.