These are stereograms of two sets of random lines. In one set, “the forest”, the lines are at different depths. In the other set, “the plane”, the lines are all at the same depth. For forest or plane alone there is no illusory contour along the aligned edges either in the monocular or fused images. When the two sets abut there is a weak monocular illusory contour. If the left and right images are fused the contour becomes much stronger when the plane is in front but virtually disappears when the forest is in front. A forest cannot be an occluder.