That's neat - makes me think of 2D light-cones. The author doesn't mention it, so I'm not sure if he noticed - but this method is trivially extensible to weigh

That's neat - makes me think of 2D light-cones. The author doesn't mention it, so I'm not sure if he noticed - but this method is trivially extensible to weighted Voronoi graphs. All you need to do is change the gradients of the cone such that d(radius)/d(z) = weight (and that makes things significantly easier when you need to deal with curved inter-cell boundaries). This potentially could be used to generate 3D voxels, but you'd need depth buffer support in 4 dimensions.