title: Clarifying Scikit Image Marching Cubes algorithm "spacing" parameter?
body: <p>I have a 64x64x64 occupancy grid (0 is the level) on which I'm trying to run marching cubes to generate a mesh. In trying to debug some issues with the generated mesh, I wanted to clarify what the "spacing" parameter means. The documentation <a href="https://scikit-image.org/docs/dev/api/skimage.measure.html#skimage.measure.marching_cubes" rel="nofollow noreferrer">here</a> says "Voxel spacing in spatial dimensions corresponding to numpy array indexing dimensions (M, N, P) as in volume.", but I don't quite get what that means. Any clarification would be appreciated, thank you!</p>