Mesh cavity detection in grasshopper

[DanielPiker]

It’s not entirely clear to me what you’re asking, but one way to show concave regions would be to measure distance from the convex hull:

concavity.gh (139.6 KB)
(using https://www.food4rhino.com/en/app/meshedit for convex hull)

If instead you want to look just at local curvature, then something like this:

Mesh Curvature confusion

There’s something in Kangaroo for this (I needed it to get angles when creating hinges from a mesh) You can use the ‘HingePoints’ utility to get the points of the pair of triangles around each internal edge, and then take the angle between the normals. If you also take this angle in a plane normal to that edge, you can get positive and negative values depending whether the crease is concave or convex: [meshangles] MeshAngles.gh (33.2 KB)