Tool to fix featureless areas

[simonbethke]

This shows a general issue with photogrammetry and gaussian splatting when capturing featureless areas. In this example imagine a room seen from the top with a white wall in front of the camera.

While the corners of the room feature good detail and can easily get placed in space correctly, the featureless white wall causes bad reconstruction.

The first two images show how 5 cameras take photos with their respective FoV. In image three, the angles the corners is marked as dashed lines. The form a triangle in front of the white wall. Within this triangle, splats can exist anywhere as there are no features to match.
Looking at image four and five, this is what happens, the splats live in front of the wall which causes the wall to get a convex surface.

To rectify this, a tool would be helpful, that allows to define the plane of the wall first. After that, splats that are in front of this wall need to be pushed back until they don't reach into the room anymore.