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When creating LOD meshes for your project's Skeletal Meshes there could be instances when specifying the number (or percentage) of vertices, instead of triangles, to retain gives the control needed to better fit memory or performance targets. Generally speaking, the memory footprint of a Skeletal Mesh is related to the number of vertices, while certain rendering costs are more closely tied to the number of triangles. The Termination Criterion option in the Skeletal Mesh Reduction tool gives you the ability to change the way the simplifier recognizes that its work is done. In the follow how-to we will take a look at the various ways you can control this setting.

Steps

1. First, locate a Skeletal Mesh that has two or more LOD's generated for it and open it up in the Skeletal Mesh Editor.

2. Make sure the first LOD is selected and then expand the Reduction Settings .
   

3. Change the Termination Criterion from the default of Vertices to Triangles and then press the Regenerate LOD** button.
   

End Result

Once the Regenerate LOD has completed, you will have a version of the Skeletal Mesh that has been optimized until reaching a target percentage of Triangles, not Vertices.. In the image sequence below you can see what happens to a Skeletal Mesh when the Termination Criterion was set to Triangles , Vertices and First Percent Satisfied**.