Stock Pile Volume Accuracy
or Accuracy or Precision?… the Software matters.
Many professionals are asking for a very high resolution when they map the stock piles volume from the topography they got with their UAV.
Precision Looking closer, it appears that the way you will calculate volumes on stock pile is even more important than the resolution.
A very good resolution will give you… let’s say 2cm by points. So you know about the texture of the stockpile and the height. Nice.
Reference base When you calculate the volume, you draw the contour base of the stock pile. When you do that, you actually draw a full surface which will be the reference base. The area is fine. But how about the height and the shape of that reference base?
The software will have to take into account all the volume above that reference, therefore it is very important that the base kind of follow the ground…
Remember, you wanted a 2cm precision on top of the pile… great, but the difference between the reference base and the real pile, underneath yes, should be excactly following the ground then.. and trust me, the ground is never plane not flat. It has its own shape and its own slope.
And more than that, every single centimeter or inch between the reference base ‘assumed’ by the software and the real pile base will have a huge impact on the result, while the top is not that important because it is thinner.
The image on the left hand side shows some stock piles on a ground that appears to be flat. But by playing with the height colors, we can see and even measure that the ground has a shape and the height difference is by 50cm.
So, if you really care about accuracy, pay more attention to the reference base more than the precision of your 3D.
I am using a software that can follow the ground whatever its shape. It is very accurate since you can choose between differents algorythms:
If the ground looks like the picture above, then I would go for this algorythm: