I have a 3D shape, defined with a triangular mesh model (2 matrixes: one of points; 1 of indexes of points defining triangles). I have some points of interest on this 3d shape. How can I calculate tangent planes to the surface for these points?

Matlab has many functions and ways to do it, but it somewhat always relies on having the equation for the surface. This time, I don't.

Alternatively, I could use points around my points of interest to estimate my tangent planes, but how do I select these points accurately, and in the proper axis?

Thanks ahead for your help.

Answer 1

[Massimo Zanetti]

You need to find the tangent plane that contains all your points of interest? Are they co-planar or not? How many tnagent planes do you have to compute?

Answer 2

[Nicolas Pedneault]

Thank you for you reply.

I am looking for 1 tangent plane per point, the plane being tangential to the 3D object surface at that exact point.

Alternatively, I thought of a way to approximate that plane: each point of interest is part of many triangles in the 3D object definition matrices. I could find all the other points of the triangles to which my point of interest belongs, and then build a plane from these points. It would not be perfect, but I think it would be closed enough... closed enough for what I need I believe.