# 3D contour mesh computation

I have the value of a function in three dimensions, $f(x, y, z)$, which varies smoothly.

I would like to compute a 3D mesh where $f(x, y, z)$ has a particular value.

Are there algorithms to do this? (And if so, any implementations?)

Note: This is the 3D equivalent of finding a contour of a 2D function, $f(x, y)$:

## 2 Answers

I think you could use the "marching cubes" algorithm. If memory serves, it requires a grid of samples as input, so at the very least you should be able to sample your function and run the algorithm as-is. You also might be able to modify the algorithm to callback to f directly. There's a popular implementation at http://paulbourke.net/geometry/polygonise/ that might help you get started.

• Thanks! For others, I used an implementation in scikit-image. – davipatti Jul 10 '18 at 18:17

In addition to the voxel-based approach that rchilton suggests, you could also look at Delaunay-type algorithms. For example, the Computational Geometry Algorithms Library (CGAL) has some built-in functionality for surface mesh generation with examples here. You could also try distmesh, the essential idea of which has been ported to a number of other libraries and programming languages. There's also an interesting blog post about getting distmesh3d to work just right.