How are the sample points selected? I get that they're weighted according to edge intensity, but what kind of distribution are you using in cases where there is no edge?

EDIT: I've read the code - it seems to be using random sampling. Still not entirely sure how a point can be placed at a place with absolutely no Sobel response - maybe it can't, which would make sense. My question arose after looking at: https://i.imgur.com/9YHOtQ0.png and then https://i.imgur.com/XRF7mz4.png. It looks like samples have been placed in regions with no response, but perhaps my eyes just can't see the edges.