Reduction

Overview

The Reduction processor takes an input scene and reduces the number of triangles and vertices in the scene in a heuristic manner by gradually removing vertices and triangles from the scene.

Targets and stop conditions

The reduction runs until one or multiple criterias have been met. The target can be a specific triangle count or ratio. But it can also be be set to a maximum deviation threshold or set to be optimized for a specific on screen size - meaning the remaining triangle count won't be known prior to reduction, but the quality will.

Reposition vertices

Simplygon can reposition the vertices after reduction to better emulate the silhouette and volume of the original model (with the SG_DATACREATIONPREFERENCES_PREFER_OPTIMIZED_RESULT flag).

Max Edge Length

This setting can be used to limit the length of the edges of the triangles of the LOD.

Geomorph

When creating a LOD with the Reduction Processor, Simplygon has the possibility to create a Geomorph model for the original model. This Geomorph model contains the same number of triangles as the original model, and contains all corner / vertex data needed to morph the original into looking like the LOD. Usually this data are the common fields such as vertex colors, UVs, normals, tangents, bone-weights etc, but it can be any data fields that has been loaded into the Geometry. Using Geomorph right before swapping between the models gives a smooth and pop-free LOD transition.

Symmetry

Simplygon detects if a mesh is symmetrical and mirrors the reduction on both sides of the symmetry plane. Symmetry re-triangulation - Symmetric re-triangulation creates a symmetry in the triangulation, where possible, of a mesh before processing. Typically, this is useful when working with triangulated quad meshed, where symmetric features are present, but where triangulation is asymmetric with respect to some given plane.

Supported components

The Reduction processor works with:

Bone reducer
Accessible from the bone settings.
Material LOD
- Mapping image
  Accessible from the mapping image settings.
- Parameterizer
  Accessible from the mapping image settings.
- Chart aggregator
  Accessible from the mapping image settings.
- Material caster
  Use it after the processing with the generated mapping image.
Normal repairer
Accessible from the normal calculation settings.
T-junction remover
Accessible from the repair settings.
Visibility
Accessible from the visibility settings. Use it to remove non-visible texture space and triangles.
Welder
Accessible from the repair settings.