Volumes on tilted grounds where it is not possible to position ground vertices.

[Isaac H. E.]

Hello,

Let's say I want to measure the volume of a stockpile sitting on a sloped terrain and half surrounded by a vertical wall like the one shown in the following image:



To do so I have drawn a rectangular polygon covering the road "faltish" surface, then I set the drawing plane to the rectangular polygon and last I created a new polygon that surrounds the stockpile in an Ortographic view (like the one shown on the screenshot).

If I click on "Measure" option in the "Model" view for the polygon surrounding the stockpile I get a list of 3D coordinates where the height of each vertex is within the 3D reference plane which is what I want however If I go to the DEM or Orthomosaic views the height of each vertex of the polygon are projected in to the stockpile surface which means that if I use a "best fit" plane as means to compute the volume I will get a wrong result.

In summary, would it be possible to implement a way to measure volumes sitting on tilted grounds and (partially) surrounded by walls?

If I missed the way to do it please excuse me.

Best regards

Isaac

[SAV]

Hi Isaac,

You could use Virtual Surveyor to estimate the volume. See here:
https://youtu.be/e7fizU7aQk0

I agree with you, it would be great if these more complex volume measurement tools were also available in Metashape.

Best regards,
SAV

[Isaac H. E.]

Hi SAV,

As usual, very useful responses!

To achieve what I wanted to do I believe I would have to purchase a subscription plan to "Virtual Surveyor" web based software which is far from my preferences in regards on how I like to pay for software so I prefer to wait until Metashape provides a method to compute that kind of volumes (to me it looks like most of the required elements are already there because I can draw the reference plane where I wanted to be and tilted like I needed it to be...)

Many thanks 

Isaac

Many thanks for the effort SAV

[SAV]

Hi Isaac,

Indeed, it shouldn't be too tricky to implement this feature into Metashape. The SET DRAWING PLANE function is already the first step into the right direction. But as you mentioned in your initial post, at the moment the Z coordinates are inherited from the mesh/DEM even when you are digitising on a manually set drawing plane.

In case you have a 3D model of the bench before and after blasting/ground work, then you could export both point clouds and use CloudCompare to calculate the cut-and-fill volume. 

https://www.cloudcompare.org/doc/wiki/index.php?title=2.5D_Volume

All the best.

Regards,
SAV

[Kiesel]

Hi Isaac,

I don't know if that is of any help for you, because I haven't used that for volume calculation but for 3D-drawing.
I use the dense point cloud to draw 3D-Polylines with the shape function and export them as DXF (when you do it in orthomosaics or DEMs you only get 2D-polylines as you already know). I then open them in AutoCAD for further use.


Regards,

Kiesel