Bones to Prioritize

Taking a look at using a Skeletal Meshes bones to restrict what is optimized.

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While the Skeletal Mesh Reduction tool does a great job at reducing the triangle count of Skeletal Meshes, there could be instances where the reduction is a little too aggressive in certain parts. To provide more control over what is optimized and what is not, the Bones to Prioritize list to helps make sure that any geometry skinned to the bones in the list will not be optimized. This works because the simplifier collapses edges, one at a time, always choosing the edge with the lowest associated cost to collapse. Bones to prioritize allows the user to specify details they wish to retain, by telling the simplifier that vertices associated with a prioritized bones have a specified increased cost of simplification.

In the following how-to we will take a look at how you can use the Bones to Prioritize list to better control which parts of your Skeletal Mesh are optimized.


  1. First, locate and open a Skeletal Mesh and make sure it has a at least three Level Of Detail (LOD) created for it.

    Click for full image.

    We will be using the default Mannequin that comes with the First and Third Person template.

  2. In the Asset Details panel locate the LOD Picker section and click on the checkmark box next to Custom . This will allow you to see all LOD's in the Asset Details panel.


  3. Next, expand the LOD Info that is under LOD 2 [generated] .


  4. Look for the Bones to Prioritize option and then press the plus sign icon to add a new element to the array.


  5. Click on the newly created input, None and from the displayed list pick the bone that needs to be prioritized. For this example we are going to make sure the hands are not optimized so the first bone that needs to be selected is hand_l .


  6. Repeat this process until all of the bones for both the left and right hands have been added to the Bone to Prioritize list


    If you are using the Mannequin your Bones to Prioritize list should have 32 bones selected.

  7. Once that has been completed, locate the Weight Of Prioritization input and set it's value to 5,000 and then press the Rengenearte LOD button.

End Result

When the Regenerate LOD has finished processing, a newly created Skeletal Mesh LOD will be created that has a reduced triangle count everywhere except the hands like in the following image comparison.

Bones To Prioritize Not Set Up

Bones To Prioritize Set Up

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