Yeah, when I need neighbouring pixels I extract overlapping chunks. As far as the edge of the scene - there aren't any perfect solutions that I know of. You cou

Yeah, when I need neighbouring pixels I extract overlapping chunks. As far as the edge of the scene - there aren't any perfect solutions that I know of. You could try to fudge it by modifying the algorithm to handle the edges with fewer pixels, or perhaps use data from different scenes as an approximation. Or you may simply lose the data there.