DJI M3M Terrain Following

[Raptor]

Has anyone been successful using Terrain Following on the M3E or M3M? I have an M3M and have made several attempts using an imported DSM and Terrain Following. I constantly run into an error related the RTH elevation not being high enough. I adjust it all the way to 392-394 ft with no success. I check the min/max values of the elevation models. I convert from ortho to ellipsoid height and export using EPSG 4326 projection. So far DJI support has not been helpful in resolving the issue. Below is a link to Dropbox folder with elevation models and screenshots. If you have a few minutes, please review and suggest how to make this capability work. I have also attached a couple of screenshots.

Dropbox

www.dropbox.com

Thanks,
Mike

 

[SteveBCH]

Has anyone been successful using Terrain Following on the M3E or M3M? I have an M3M and have made several attempts using an imported DSM and Terrain Following. I constantly run into an error related the RTH elevation not being high enough. I adjust it all the way to 392-394 ft with no success. I check the min/max values of the elevation models. I convert from ortho to ellipsoid height and export using EPSG 4326 projection. So far DJI support has not been helpful in resolving the issue. Below is a link to Dropbox folder with elevation models and screenshots. If you have a few minutes, please review and suggest how to make this capability work. I have also attached a couple of screenshots.

Dropbox

www.dropbox.com

Thanks,
Mike

I had a similar error when doing Terrain Awareness flights with my Phantom 4 RTK so not sure if this exactly applies but might be something to look into. I thought I had set up the mission perfectly yet the drone wouldn't launch and I'd get an error message. The flight area had a lot of vertical such that the elevation change from my launch point to the highest elevation over which I was going to fly was about three hundred feet. I had initially entered a max height of 394 feet. Apparently, when the controller compared the launch point elevation with the highest elevation the drone was going to have to fly to be over the highest ground point, the controller was unhappy. Nothing made sense so I started increasing the max height in 100 ft increments until the controller was happy and allowed the P4 to launch. I think I ended up with a max elevation of something like 700 or 800 feet before the controller was satisfied. I never flew more than a couple hundred feet over the terrain so all was very much in compliance with the rules. After that adjustment to max height, everything went perfectly and I got really good results.

Another lesson I learned when using TA was to launch from near the lowest elevation when flying a longer, steep valley and was planning to simply walk with the drone as we moved up the valley, land, swap batteries and then continue. I had initially thought I'd save some walking distance by starting with my first launch point up the valley a ways from from the down valley end of the flight area; about 1000 feet horizontal which is near the upper limit of how far I can maintain visual (but also having an observer closer to the drone and make him walk instead of the old guy). When the drone launches in a TA flight, it goes straight up to the needed altitude for the first photo point (according the the DSM in the controller) and then takes off horizontal in a dead sprint to that first photo point. Turns out, if your first launch point is at a much higher ground elevation than the ground under the first photo point, and you have trees around, the drone will go up and make the dead sprint toward its first photo point regardless of the trees that are in between. Scared that daylights out of me as the stick controllers did nothing to slow it down and I thought it was going to crash into a tree. Fortunately its obstacle avoidance kicked in and the drone paused and hovered until I hit RTH.

Also, the surface model elevations are good but may not that precise. Before you initiate a TA flight, manually launch and fly over your launch point to confirm your programmed height is where you want it. I had one TA flight that was was about 50 feet lower than expected.

Best of luck.

 

[Raptor]

Thanks for all of the info and insights. I will check the elevation of the launch points for the TA surveys I tried. In each case I was using the DSM from the previous survey I flew.