Backface Culler is a tool to help optimise scenes with a static camera or those with a locked viewport such as top down.

How it works is the tool will use a given cameras viewport to perform some frustrum culling. Then it will check the direction triangles are facing and remove those facing away from the camera within a given threshold.

By doing this you can save disc space, memory and rendering time.

Please note that this tool doesn't read from the shadow map! What this means is that although a face might not the visible to render, it might still be important to cast a shadow.

In these situations it can be better to use the original mesh to cast shadows and the optimised mesh to render.

Backface Culler will output your meshes in the .Asset format. This is readable by Unity but if you want to edit them in external software you will need to use the ProBuilder package to export them to .obj