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Stockpile measurement


I am new to drones and I am trying to measure my first stockpile.  I flew it with our Phantom 4 pro v2, at 225 feet, with an 80/80 overlap.  I used DJI map pilot for my mission planning because I use my android phone to fly the drone.  I got my job processed on Maps Made Easy and drew a polyline around the pile.  It says the following:

Volume: 172.67 CY

Void:  362.27 CY

Area:  565.40 SY

I then measured the stockpile by hand with GPS and got 2316 CY.

I am wondering what I am doing wrong?  The overlap report doesn't have any dots for a good portion of the top of the pile.  I assume this is the major problem?  Thanks for the help!


Ted Hoodjer

Official comment


If you do too small of an area the 80% overlap isn't really doing its job. The point of doing 80% overlap is that everything gets 25 looks at it for the processing. Your map only had 3 rows of images so the most anything was ever going to get was 15 looks. 

You need to have 25 looks at everything if you want to have accurate 3D models. An accurate 3D model is required for doing solid volume measurements. 

You also want to make sure that all of the images are collected while travelling at the same speed. Map Pilot does this for you in Active Connect mode. I am not sure what app you are using but you might want to look at that. 

Also, make sure you are using lots of points to draw your measurement polygon (~20, not 4). 

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What do you recommend for flight planning for this situation.  Height?  Overlaps?  Speed?  Anything else?  A single pile that is roughly 100 feet long by 50 feet wide, with a max height of 15' or so.  The app I used, DJI Pilot, does have a speed for collection of 11 mph (i think that is what it was set at).  Thank you for the help!

Ted Hoodjer 0 votes
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Sorry for the delay. When you really care about the accuracy of the 3d models (for stockpile measurements you really do) you need to use 80/80 overlap. 100 ft is fine for 15 foot stockpiles. Flying that low will severely limit the speed you can fly to about 7.3 mph. You can fly faster the higher you fly. Our Map Pilot app does all the speed selection for you. 11 mph will stretch that 80% along track overlap down to probably 65% which is not enough. Luckily most stockpile areas are pretty small so even with the slow speed it should be able to be done in one battery.

Zane 0 votes
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