DJI RTK, Shooting "Known Point" and L1 Coordinate System Processing

DJI L1
1

Any Surveying/P1/L1/Terra experts out there?

  • Prior to flying a mission, we understand it is best to place the RTK system over a known point (and then manually input the known point data via the Smart Controller). In most of our projects, there are no existing known points thus we have to shoot our own. The question is what coordinate system do we need to shoot the new “point” so it can be injected into the DJI smart controller prior to flight? Is it just WGS 84 / Ellipsoid?
    (and yes we know to SUBTRACT 1.8m from the “known” point before entering the vertical height in the DJI RTK system)

  • Second question is, in DJI Terra, we see you can select a Coordinate System prior to processing L1 files. We normally select WGS 84 / UTM zone 15 (as we are in Louisiana) and leave the Altitude Settings as Default. Is this correct?

Any help is appreciated! (photo for reference only)

2

Unsure about the first question. I would keep it in WGS84 though if it were me.

Second question, yes you are correct. You can always adjust the vertical easily enough in the Rock Cloud once you’ve got GCPs, and inevitably there is going to be a little miss on the vertical in a lot of instances. If the X and Y are spot on you can line up the vertical pretty easily once you’ve got your desired output projections.

3

BTW: I was incorrect in my first point. You ADD 1.8m to the height of the “known” GCP/point where you plan to place the RTK 2.

DJI really needs to improve this process.

4

Im in the Ohio, Indiana, Ky area. We hook-up there with the NTRIP network and stuff has been spot on.

5

Concur about NTRIP being spot on. I am in Louisiana and subscribe to the NTRIP operated by LSU Center for Geomatics (C4G). We use this service with our Trimble rovers and it is very accurate. I recently connected the DJI 300 Matrice to C4G on a test site and the results look very good from a visual stand point. Will be trying it on more sites and hoping for the same results. If so, this will be my new workflow (assuming I have cell service at the site). No worries about the base station set up, known points, antennae heights, etc.