So I’m not sure what is happening with Paul and his Mavic, but we’ve done a bunch of investigation into this the last couple days. What has happened is that we have fixed an issue in iOS where we were taking way too many photos. Android still has this issue and is now being fixed. @mineralix are you sure that the 245 photos that you took are useless? Can you upload them to DD map engine and let us verify the overlap?
Thanks,
Chase
Hi Paul,
I use a Mavic and DD for forestry mapping. Some things to try:
Maximize your altitude. If you’re flying missions at 200’ over 130’ trees on flat ground, that means you only have 70’ of clearance between camera and treetop, so it won’t stitch, no matter what your overlap is. In the US it’s permissible to fly 400’ above obstacles, so I always fly at 400’ clearance over the tallest timber in the mission. For example, if the trees are 150’ tall and terrain has a 50’ uphill variance from my LZ, mission height is 150’ + 50’ + 400’ = 600’.
Make sure that you have GPS lock before quitting DJI Go and opening Drone Deploy. Don’t quit DJI Go until it does. If it doesn’t get a lock, your RTH will be wrong.
Sidelap is a function of how many turn waypoints you have in your mission- that’s easily changed by the sidelap setting.
Frontlap is not based on GPS points. It’s achieved by shooting images at a fixed time interval based on the speed you pick. (in iOS anyway). Consistent frontlap assumes that your UAV is traveling a constant speed, which is not always the case. If you’re flying in wind taking photos at a constant interval, your upwind frontlap will be high because your UAV has a slower ground speed than what you set. Conversely, your downwind frontlap will be low because your UAV has a higher ground speed, and photos are being taken at the same time interval as in the upwind leg. (See the image below.) This spacing problem will cause holes, poor stitching, and distortions in your map. Solution is to decrease your speed so you get consistent frontlap even if you have a bit of a breeze. I’ve been setting it to 25 mph as a baseline, then dialing it down if it’s breezy to decrease ground speed variations.
Set focus to manual and center-weighted exposure.
There have been problems with autofocus and exposure on the Mavic, not sure if they’re resolved. To avoid issues, make sure that “Automatic Camera Settings” under “Advanced” in your DD mission is turned OFF, and that DD is not running when you turn the Mavic on. It should always be started with DJI Go running.
After you’ve calibrated the compass and established a GPS homepoint In DJI Go,
a) Set focus to Auto
b) Zoom in on an object the same distance away as your mission clearance height
c) Tap the object to auto-focus on it - it beeps when focused
d) Switch back to manual focus so you lock in that focus distance
e) Zoom out to 1.0x
To get center-weighted exposure:
a) Tap the green focus box to turn it into the exposure circle
b) Tap the screen anywhere, then and tap the “+” on the circle. The circle goes to the center and makes a box. You’re now set to center-weighted exposure.
You can quit DJI Go and open DD to load your mission.
If you have to change batteries, quit DD and re-focus using the steps above, then quit DJI Go and reopen DD.
Hope this helps!
-Dan
Sorry, I use DD only for Ariel flights and 3D Survey for 3D modelling.
Could upload the camera positions and the resulting orthofoto, but do not find a button here for uploading jpg’s
Forgot to mention: we used a iPad mini for flying
I am having the same overlap issue as Paul.
I have flown several small test flights and I am having trouble getting the forward overlap to work properly. The drone works perfectly, snaps pictures, shoots video, flies correct, steady gimbal, the whole shahbang, it just does not do the frontlap properly.
I just read Dan0’s post that said that frontlap is based on windspeed not groundspeed. Does frontlap take into account height? I have flown some missions that were super low assuming that it would take pictures more frequently to account for the fact that it is lower. Is this not the case? Does DD ignore height when calculating how much frontlap to use?
I’m going to go back to out later today if the weather clears up and give it another go with a higher altitude, slower speed and the new version of the app. I’ll report back my results.
Ok turning things up all the way to 90% and flying at 300feet+ seems to be able to produce a good map. It feels like that setting is useless if I have to have it all the way up. I guess what I really care about though is it producing a good map.
I am having the same results which I email Chase and Manu about . I now have to crank it up to 90%-94% to get useable results when before, I would have 70%/60% to get good results.
I recently switched to skycatch and everything how is used to be with my phantom 4 pro . No more image skipping.
By the way , I am on IOS.
I have a similar issue and didnt see this thread until now so I opened a new one here Images uploaded but map incomplete - #2 by behzad but the lack of images in my run means i may have the same issue… any resolution?
Any way to verify the mission was run correctly while out in the field? With a laptop etc…? I am now going to have to drive 2hrs back to the site to reshoot.
Unfortunately I don’t use drone deploy for processing. I use Pix4d which has rapid check.
You could try 94% front over lap and 90% sidelap to get good results.
How is pix4d vs dd? I am new to the space.