How to preserve topology during polygon optimization

About this document

InstaLOD allows users to paint vertex colors on geometry to have point-precision over where to optimize, and where not to optimize. Vertex painting can also be used in the 'CAD Live Link', to fix shading issues on CAD data.

Vertex Painting

Select the paintbrush icon  in the toolbar to access the 'Vertex Paint' Mode, select a mesh and 'Begin' painting.

InstaLOD supports vertex color set and selection set based optimization weights when performing polygon optimizations. This is a great way to give artists full control over the optimization.

• Vertex Pinning, use the blue vertex color channel to mark vertices as important. Values between [0...1] will increase the weight of the vertex. A value of 1 marks the vertex as pinned and therefore not as collapsible.
• Vertex Cullable Detail, use the red vertex color channel to mark vertices as cullable detail. Values between [0...1] will decrease the weight of the vertex. A value of 1 means the vertex will be culled as early as possible.
• Vertices within a selection set are not collapsible
• InstaLOD will only accept vertex color channels that have an empty green channel.

Avoid using both red and blue for a single vertex. If both red and blue channels are used on the same vertex the higher color value will determine the weighting type. It is recommended to use pinning instead of culling, to avoid interfering with the optimization strategy of the optimizer.

IMPORTANT: Please note that using different color channel values will not reduce the pinning or culling behavior by the same factor. Channels with different brightness values change the importance of the area, not the percentage that is culled or pinned. 

As an example, using a blue color value of 127 (50%) will not result in the area being optimized by 50%. It will simply specify that if there are no other polygons that can be removed around the model, that this area is touched first, before moving on to areas with brighter values

To enable vertex-based optimization weights, select an option in the 'Optimizer Weights' dropdown box under the 'Advanced' settings of the 'Optimize' operation.

This workflow is also demonstrated in one of our YouTube videos using InstaLOD for Autodesk Maya:

Fix Shading Selectively on CAD Data

Vertex paint can not only be applied for the selective optimization on models but also allows for unlimited control over fixing shading on CAD data. Typically, Shading settings get applied to the entire object by retessellating a part. By using the 'Manual Adjustments' settings, vertex colors can be painted and applied selectively.

Use a white vertex color to mark vertices where shading should be applied. Values between [0...1] will specify the weight of the settings applied to the vertex. A value of 0 (Black) means the shading settings will not be applied to the vertex.