hmmm I have no idea what I am looking at… that looks more like a bounding volume trace like VolumeDecals more than POM… are you trying to POM using virtual plane coordinates or somesuch?
If you can post some more info like a small thumbnail of your heightmap and what the actual geometry looks (above shape looks like a cube, but the UVs appear to not be a cube so I have no idea) it will help us debug.