Strange volume numbers

[Misha]

Hi!
I have a very simple cloud, basically it is a rectangular hole in the wall and I need to calculate volume.
CC box dimensions are close to real physical numbers, but when the volume is calculated it is nothing like it should be.Please see the screenshots. Another thing that looks strange for me is that calculated number depends on projection direction. Shouldn't it be the same (more or less) for this rectangular shape? Thank you in advance!

Misha

[daniel]

The 2.5D calculation volume is not really meant to be used on a 3D shape. You would need indeed the cube borders to be perfectly aligned with the main axes, and you would also need to slice it in two ideally (so as to compare the upper part with the lower part (that's how this tool is supposed to be used).

And last, make sure to use a realistic 'step' value (considering the low density of the cloud). Beware of the warning about a too low number of neighboring cells when you compute the volume.

[Misha]

Daniel, thank you fr the reply!
I sliced one side of the box, Z dimension is depth now, but numbers still don't much. I don't expect them to be exact,

11.jpg (426.27 KiB) Viewed 8180 times

, but the difference I have is too big I think.

Thank you,
Misha

[WargodHernandez]

It looks like you have cell height set to average and empty cells set to interpolate for volume calculation. this can introduce issues especially with those "this walls" surrounding the edge of the box.
Also how parallel is the far red colored plane to the Z axis? it looks like one of the side walls on the left hand side isn't on the outside edge relative to the Z projection.

[Misha]

WargodHernandez,

Thank you very much for taking a look!
Changing how to deal with empty cells produces more realistic results only if I set up it for 'Leave empty' (CC complains about sparse cloud in this case) or when I set it for 'user specified value'. In latter case it doesn't matter what number what number I put in, volume number stays the same. Changing cell height won't make much of a difference.
I think what you refer is some imperfection in one of the corners. It is actually a real scan of a real hole :) I attach the file, it you have time please check.
I'm sorry for all this questions, but I'm new to this knowledge and want to understand what is gong on before getting to more complicated cases.

Thank you,
Misha

[daniel]

Seeing the low density of this cloud and the fact that it's a 3D shape (not meant to be used with the 2.5D volume calculation tool - especially the overhang of the top borders) I don't think you'll get a reliable result this way.

[Misha]

Daniel,

Thank you for your time and advise!

Misha