Sebastian Schröder

polyreduce will turn most primitves into triangles which by their very nature are always co-planar. certainly the easiest way to achieve your desired result if triangles are acceptable.

not sure if houdini has functionality for that built in somewhere, but there is a lot of software out there that will generate a depth map from an image.
http://depthy.me/#/ [depthy.me] i hope it's okay to post links here.
i'd use that to displace a tessellated plane, cap the back and turn it into a volume.

how are you normalizing your positions before baking them? substance designers position maps are in object space and yours need to be as well .


this inside a point wrangle will normalize your positions relative to the bounding box.