Hide occluded vertices

Question

Background

Using Blender 4.1 and a wireframe modifier to project a mountain mesh as a blueprint. Subterranean structures must remain visible. I'd like to remove parts of the mountain that aren't directly observable from the camera's perspective. Consider:

Setup

Modifiers:

Ignore the topmost modifier.

The Geometry Nodes:

The node setup, which uses the dot product of the camera and the mesh normals, removes the majority of hidden faces.

Problem

Using the normals doesn't eliminate all faces that would be invisible from the camera's perspective, as shown here:

When rendered, faces from behind the mountain are appear as a broad white band:

I'd like to eliminate that white band.

Idea

Here's the node setup for raycasting:

That setup doesn't delete any vertices, despite the lines showing an intersection of the rays and the mesh:

Manual

Here are the steps taken by hand to achieve the desired effect, using the Blender 2.9 keyboard hotkeys:

1. Select the mesh.
2. Press NUM 0 to change to the camera's view.
3. Press TAB to enter edit mode.
4. Press a to deselect all vertices.
5. Press b to enter vertex selection mode.
6. Click and drag to select all visible mesh vertices.
7. Assign to a vertex group.
8. Add a mask modifier.
9. Assign the vertex group to the mask modifier.

While this works, an automated way would be most welcome.

Question

How would you render a mesh wireframe such that all occluded faces are not rendered (i.e., the occluded wireframe is suppressed) while objects inside the mesh may be seen?

I'm using Geometry Nodes but other solutions are welcome.

Answer 1

The raycast setup is very simple:

As mentioned first by Chris later by me in comments, the effect is not ideal, because it works on vertices and doesn't cut edges/faces:

Perhaps the resolution is satisfying enough, however, because it happens far enough, or the mesh is subdivided well enough:

But for wireframe modifier typically you want low poly so I don't know... Maybe you could use simple subdivision and then keep only edges that where there before subdivision:

I use a 0-extrusion hack as a quick workaround for the wireframe modifier requiring faces, but you try better workarounds...

This is an x-ray mode both to show the wireframe is not visible behind the Occluder Monke, and to get rid of artifacts caused by doubled wireframe (which you could try to mitigate with Weld modifier maybe).