Hi! Probably this isn't issue, but browsing through your code I coudn't find any solution. The point is that I'm trying to draw a "map" where contours (or layers) have both humps and holes (see figs attached). And in some holes the bottom layer is zero (pixels must not be filled). But when I subsequently overlay the contours and add the zero contour to the top, I see not an empty hole but the last underlying contour with minimal, but non-zero value. Could you please give some advice, how I could solve this problem?

Thanks in advance,
Dmitry