Reduction -

The Reduction component offers features such as triangle count reduction of the geometry, welding of vertices, new normals calculations and removal of T-junctions.

Tip

Check out the Reduction article to learn more about the Reduction processor.

Main settings

• [%] [Pixels] [Triangles] [Deviation] - (Reduction type)
  The reduction type determines whether triangle reduction shall be based on:

  • A percentage of the original scene's triangle count
  • A targeted on screen size expressed in pixels
  • A fixed triangle count
  • A deviation expressed in scene units
    
    

• Vertex repositioning
  Vertex reposition determines how much "freedom" Simplygon has when it comes to altering vertex/triangle data. Allowing more altered data means it will be easier to create good looking LODs, but without altered data it will be easier to keep the memory-usage in the LOD-chain more optimized. Available options are:

  • Use original
  • Prefer original
  • Reposition vertices
    
    

  Note

  Use original will preserve all vertex and corner data. Features that requires certain data to be modified, such as BoneLOD, will be disabled.
  
  Prefer original is recommended for blend shapes to avoid "floating vertices".
  
  Reposition Vertices is recommended for most assets to compensate for pixel errors.

• Reduction heuristics
  Reduction heuristics determine how precise the reducer will be during the mesh reduction:

  • Fast
    Reducer will be faster, but on screen size and triangle count will not match perfectly.
  • Consistent
    Reducer will be slower, but on screen size and triangle count will consistently give matching results.
    
    

• User weights
  If set, the reducer will weight the reduction based on the vertex weights defined by using the Paint tool.

• Selection set
  If set, only the specific geometries in the selected selection set will be processed, otherwise the whole scene will be processed.

Reduction feature importance settings

The feature importance settings can each be set to one of the importance values Lowest, Low, Normal, High or Highest depending on processing requirements. Importance settings are relative, which means that setting all of the settings to High will give a similar result as when setting them all to Normal.

• Silhouette
  A higher value will result in a higher silhouette preservation.

• Material boundary
  A higher value will result in better borders/boundaries between different materials.

• Texture stretch
  A higher value will preserve texture coordinates better, thus introduce less distortion of the texture.

• Normal
  A higher value will result in a higher normal/shading preservation.

• Object boundary
  A higher value will result in a higher preservation of boundaries between objects.

• Animation
  A higher value will result in higher animation/skinning preservation.

• Vertex color
  A higher value will result in higher vertex color preservation.

• Edge set
  A higher value will result in higher edge preservation for the specified edges (currently only supported through the Maya/Max plugins).

Reduction repair settings

The repair settings covers handling of unconnected parts and unwanted gaps in the geometry. It consists of two parts; Welding and T-junction removal.
Welding merges vertices that are closer than a set distance from each other whereas T-junction removal finds open edges that lie within a set distance from other open edges.

• Weld distance (in current scene units)
  Vertices within the specified distance will be merged.

• Weld only object boundary
  If set, only object boundaries will be welded.

• T-junction distance
  If enabled, T-junctions within the specific distance will be removed.

Tip

For further information see documentation:

• Welder
• T-junction remover

Reduction normal repair settings

The normal repair section covers parameters for repairing the normals of the geometry.

• Repair invalid
  If set, only invalid normals such as backfacing and zero length normals will be fixed.

• Hard angle cutoff
  The edge angle in degrees above which an edge is considered "hard". If the angle between two triangles is above the specified value, the normals will not be smoothed over the edge between those two triangles.

Tip

For further information see documentation:

• Normal repairer

Reduction symmetry settings

If the input geometry is symmetric, it can be reduced symmetrically to ensure that it continues to be symmetrical.

• Symmetry

  • [Off]
    Symmetry calculations disabled.

  • [Manual]
    The reducer will detect symmetric features and retain symmetry during processing using the supplied symmetry plane axis and offset.

    • Axis
      The axis which will be used for symmetry calculations.

    • Axis offset
      The position on the symmetry axis where the symmetry plane is placed.

  • [Automatic]
    The reducer will detect symmetric features and retain symmetry during processing using any detected X, Y, Z symmetry plane.

    Note

    For a geometry to be considered symmetrical, also the texture coordinates must be mirrored.