@Benjamin, I would be happy to review any documentation you can share that demonstrates that image metadata for all cameras that are supported by the DJI M210 RTK contains initial image position information that is measured by the RTK GPS and is cm-grade. Unfortunately, I have found no documentation that states unequivocally that the DJI M210 RTK reports a cm-grade coordinate location for each camera position. I do not deny that the image metadata contains an RtkFlag, but my opinion is that RtkFlag is insufficient evidence that the image geotag is in fact cm-grade. So far, it is an indication that the RTK GPS was active at the time that the image was captured but does not guarantee the RTK GPS was used to measure the camera’s position.
Furthermore, the comment from DJI technical support that Alexander shared does not inspire much confidence considering that Pix4D’s default behavior is to import the coordinates that are stored in the images’ metadata exactly as they are written. I have no reason to believe that Pix4D is “unable to get accurate geotags,” unless an ‘RTK-measured’ camera position coordinate is somehow stored differently than any other camera position coordinate.
@Alexander, Pix4D cannot confirm or deny that the image geotags were in fact measured with the RTK GPS based on the DJI flight log. The most reliable source of information will be the image geotags themselves. My opinion is that if the geotags are in fact measured with the RTK GPS that the positioning and residuals should be reported directly in the image’s metadata.
@Benjamin, Alexander, Philip, Dave, Adam, and others, a key aspect of the RTK GPS measurement that has not been addressed, in addition to the reliability of the base receiver, is the position and orientation of the camera relative to the RTK GPS. There are more RTK fixed-wing UAV solutions available today because the camera is mounted into the fuselage of the aircraft and moves in unison with all other hardware components. Multi-rotor UAVs that support actively stabilized gimbals, on the other hand, have many more degrees of freedom to account for because the camera’s position and orientation move relative to the fuselage.
My opinion is that the only way to truly determine whether or not the RTK GPS is used to measure the camera’s position is to conduct an empirical test, where you process a Pix4D project that relies solely on the DJI M210 RTK geotags and then incorporate a set of cm-grade checkpoints to independently verify the accuracy of the solution.
I cannot emphasize enough the importance of independently verifying the accuracy of any project, including when you are using a new hardware or software solution for the first time in addition to when you are working with a proven solution.