Calculating Surface Areas of Open Mesh

[lucasdkoh]

Hi everyone. I've been using CloudCompare for a while to analyze some point clouds I got of sea sponges. You can just see them as unevenly shaped rugs.

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I want to find the surface area of the sponge. Basically, the area of the top of the 'rug' (not top and bottom). I tried turning it into a mesh with PoissonRecon, which got me a mesh like this:

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I changed the 'color' to 'scalar field' and then played with the display ranges to get me this, which was pretty much exactly what I wanted - it's a fantastic estimation of the sponge's surface and area:

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And then I went into Edit -> Mesh -> Measure surface to get my surface area. Of course, I now realize that I don't think I was given the actual surface area of the sponge, instead I got the surface of the yellow box, which the original mesh entirely filled up.

Is there any way I can get the surface area calculation I'm looking for?

[daniel]

So after playing with the 'displayed' scalar field range, you should 'Edit > Scalar fields > Filter by value'. This will extract only the visible triangles to a new mesh entity.

Then you can compute the surface of this new mesh.

[lucasdkoh]

Thanks so much, you're a lifesaver!

Actually now that we're here, would there be a way to measure the perimeter of the mesh?

[daniel]

Not with CloudCompare, sorry!