It’s perfectly possible. What you basically need to do to is applying the edge detect algorithm not only to the depth buffer but also to the normals, or more specifically to each channel of the scene normals. Now if you use the sobel kernel 4 times (depth, normals r, g, b) the material gets pretty expensive so I’d rather go for a simplified version with only 4 offsets for detecting edges.
Here are some comparison screenshots for depth only, normals only and a combined approach:
http://oliverm-h.blogspot.de/2014/03/unreal-engine-4-post-processing