As seen in the attached picture, we can find the extremum points by setting the derivative of $2$D functions equal to zero. Something similar is also possible in $3$D meshes. As in the wave model and the inverse elephant model, we want a VTK Python or Unity $3$D script that detects the extremums looking down and puts a mark there. By the way, since the mesh is not a continuous function but discrete, the derivative may not be exactly zero anywhere, but if the derivative is positive in one triangle $($or vertice$)$ and negative in the next, it should be interpreted as zero somewhere in between. Of course, here, a $3$D derivative is needed, not a $2$D derivative. Here, instead of derivative tangents, normals can also be used.