Volume or related statistics of the Intersection, union and difference objects

[anish-pratheepkumar]

Hi,
I have recently started working with 3D meshes and I need to find intersection of two 3D volumes. They are defined as 3D points in space, in a numpy array. (I was working with Trimesh initially and created 3D .STL meshes for these two 3D volumes, but I couldnt find any option to find intersection between these two 3D meshes. Hence I switched to pygalmesh)

I referred to the following codes from this github repo:
to generate mesh from numpy array: https://github.com/nschloe/pygalmesh#meshes-from-numpy-arrays-representing-3d-images
to find intersection of two meshes: https://github.com/nschloe/pygalmesh#domain-combinations

In the end I got an Intersection object and I would like to know its properties like its volume for example. Is there any possibility for that in pygalmesh? Or please let me know how to figure out these properties of a mesh.

[nschloe]

Domain combinations are only for domains which are explicitly specified, not implicitly by a numpy array. If you have the domain data as arrays, and they have the same shape, it should be easy to find the intersection of the domain with some logical operations. You can pass the resulting array to pygalmesh.

After you've generated the mesh, to get the volume you can simply sum up the volumes of the tetrahedra. There are a number of libraries to compute those, e.g., meshplex, but you can also do it yourself.

[Igiteverything]

I have the same problem as Anish, and would like to ask: Given that CGAL provides the functions for boolean operations on surface meshes ( https://doc.cgal.org/latest/Polygon_mesh_processing/index.html#Coref_section ), wouldn't it be very useful to include them in pygalmesh? I am sure many users would really appreciate, and it is a functionality hardly available in any other python packages (trimesh does not have a good intersection implementation, for instance).

[nschloe]

@Igiteverything Sure, I'll be happy to review a PR!

[Igiteverything]

Touché.

[nschloe]

Touché.

?