Calculation of volume

[jocy.cruz]

Greetings,
At first I apologize for using a translator because I do not speak English.
I have a cloud of dots from a cave and I would like to calculate its volume. I performed the calculation according to the tutorial but the result is much smaller than the volume calculated by the traditional method.
So I would like to know if there is a more detailed tutorial or if they could help me know if I'm doing it the right way.
Another question I have is how much the units: the size of the grid is shown in which unit? and volume and area?

Thanks for the help.

[daniel]

If it's a cloud of a cave, then it's probably not '2.5D'. You generally can't use the '2.5D Volume Calculation' tool.

What you can do is create a closed mesh (with the PoissonRecon plugin) and then simply compute the volume of this mesh (Edit > Mesh > Measure volume). Don't hesitate to send me your cloud to see what I can do (admin [at] cloudcompare.org).

Best

[jocy.cruz]

Hi Daniel!
Thank you for your response.
and I apologize for the simple questions, but I'm not a frequent Cloudcompare user.
To use PoissonRecon, a cloud of points with normal was requested, so proceed in: edit> normal> calculate
Settings:
Local Surface mode: Surface
CloudCompare: 0.079120
Orientatation: Use preferred orientation: + Z

In the following proceed with: Extensions> PoissonRecon.
Using the parameters of the defult the created mesh does not match reality, leaving the volume much larger.
So I ask you if I am doing it correctly?

Attached is the cloud of points used.

Again, thank you for your attention.

[Gregoire]

Hi, I'm currently searching a way to calculate a volume, I have cut a small part of my model (cliff) and my process is the next...

1 - Edit > Normals > Compute > triangulation
2 - Poisson surface reconstruction
3 - I eliminated the extreme
4 - Edit > Mesh > Measure Volume

The result looks correct but I'd like to know what is the way of this calculation ? because the mesh doesn't look close.

Thank you :)

[daniel]

Don't you get a warning in the Console?! Because this method needs (normally) a closed mesh to produce an accurate volume (since it computes the volume 'inside' the triangles). If your mesh is open, it only works under very specific conditions (like the mesh should be cut at z = 0 or something like that)

[DA523]

I cant open because it is large pointcloud
Can you reduce points to 2 millions
use EDIT --->>Subsample

then post here again (zip)

[Felix]

Hi Daniel,

May I ask how does the 2.5D volume calculate the surface area? In other words, what specifically does "base surface" mean? Does the base surface include every non-empty cell? Does it include all the area on the "outside" side?

Thanks!

[daniel]

I believe it's just the sum of non-empty overlapping cells indeed.