R CM wrote:
> you must make the sum of the areas of each triangle.
> and for the mathematical volume,
> i think it's more difficult...
> perhaps with a octree method and test for each cell if
> it's indside or outside the shape...
> ( a non-trivial test ;-) )
>
> anyone have a better solution ?

For convex hull, take any point inside a volume, and compute sum of
volumes of 4-point pyramids created by each triangle of hull and this
point inside.

For open areas or models in which triangles cross each other, it is
absolutely non-trival (in addition for needing a definition what volume
means in such case).

For nonconvex hulls, you have to dissect them somehow. It is generally
compute-intensive. For some references you can try out
http://users.comlab.ox.ac.uk/joe.pitt-francis/convex_decomp_talk.ps.gz
but try out too look at google for
'tetrahedralization of three dimensional polyhedra'

Artur

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