About this document
Occlusion Culling describes the process of removing geometry from an object that is not visible.
InstaLOD features two Occlusion Culling Modes that allow for either an interior polygon detection and a camera-based mode where cameras are used to determine if the geometry is within or outside of the setup cameras view.
The 'Culling Strategy' determines what parts of an object to select - either complete objects, sub-meshes or individual polygons. Using the 'Data Usage' the user can specify what happens with the selected geometry. Either 'Remove Geometry', 'Write Into Vertex Colors' or 'Write As Optimizer Weights'.
The 'Resolution' works comparable to a ray-tracer and looks to see which parts of the geometry is visible and which parts are not.
When dealing with high-poly objects and a low resolution, holes can occur due to the resolution not being high enough to pick up all of the tiny polygons in the mesh.
What can't be seen will be removed.
The 'Adjacency Depth' protects neighboring faces when removing geometry,
0 = all faces that are not visible during rasterization will be culled
1 = direct neighbor of faces that are marked visible will also be marked visible
2+ = neighbors of neighbors will also be marked visible
The 'Submesh Face Threshold' determines the visibility of a submesh. The submesh is marked visible if its visible face count is greater or equal to the specified value
The 'Alpha Mask Threshold' considers materials and textures with alpha values equal or below to be transparent. For objects to be considered as translucent the 'Translucent Mesh Suffix' can be used.
With 'Ignore Backfaces' enabled, Backfaces will not occlude geometry. When disabled, backfaces will occlude geometry.
Mesh names that match the 'Translucent Mesh Suffix' will be marked translucent for the ray tracer. Translucent surfaces can also be set up when using textures with an alpha channel.
When not using a 'Custom Texture Page Configuration' texture names that contain the string 'alphamask' will be used as an alpha mask. When using a 'Custom Texture Page Configuration' textures that act as alpha masks must be set up manually.
Automatic Interior Mode
The Automatic Interior Mode provides a one-click solution to remove occluded interior faces. Depending on the polygon density it can be necessary to increase 'Precision', 'Resolution' and the 'Adjacency Depth' to prevent creating holes.
The 'Precision' determines how precise the object is examined. The higher the precision the more tests are performed to determine the visibility of the individual polygons.
Camera Based Mode
The Camera Based Mode maintains polygons or objects within the camera view and removes anything outside of the view.
Using the 'Render Output Path' a snapshot can be saved of what is visible by the raytracing camera.