Huge Discrepancies-Same Pile, Different Polygons

I’m having a very hard time understanding a problem on a few of my maps. I measure stockpile volumes quarterly for a concrete and aggregate supplier. They contacted me, stating that a certain stockpile is missing a lot of material. I went back through the years and summarized the volumes for the problem pile. From one quarter to the next, the volume increased by a factor of 3, with no material being added to it. I always copy polygons from map to map to keep my pile names and base plane calcs consistent. There were three quarters where the volume was excessive, then it dropped back down to realistic levels. Realizing this, I copied the polygon that had dropped in volume back to the map that showed the first huge increase in volume. With practically the same outline, and the same base plane calculation method, the two polygons measure 18,824.87 cubic yards and 66,730.86 cubic yards. I would include screenshots of the two polygons but I can only show one:

Can anyone tell me what the heck is happening here? My client is breathing down my neck to get this solved, and frankly, it is casting doubt as to the dependability of DroneDeploy.


When I hear a factor of 3 the first thing that comes to mind is feet to meters.

  • Can you enlighten us as to your drone setup and workflow?
  • This just happened all of the sudden in one map?
  • The stockpile looks exactly the same from map to map?
  • Have you done a cut/fill analysis?

It’s usually the base plane. 98% of issues with volumes are due to the base - because 40% of the pile volume is in the bottom 10%.

Best to always use 3D view for annotation of volumes. If you share the (secure) URL to the project I can take a look.

I think I found it - certainly a really tough situation because it’s not a pile on flat ground. I think you’ll have to split it into chunks to be able to accurately model the base. Thing to watch out for with triangulated is that it will use every point you place as a node in the base, even if that edge point is half way up the pile. This will be a major issue if you copy the outline but the GPS is not absolutely dialed.

As Michael said - assuming you are using RTK / PPK data you could instead use Cut / Fill to calculate the change within the region vs a previous map, but that will require a more expensive paid plan.

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I’ll add the key to using triangulated is think about placing your points as if you were shooting them on the ground like a Surveyor. You need to capture the top and the toe of the slope to create the correct triangle across the base of the pile.