Paint Reduce Weights works in conjunction with the feature to let you reduce the number of polygons in a mesh while attempting to retain the shape of the original. The Paint Reduce Weights Tool lets you paint on the mesh to specify a region on the mesh where you want the polygons to be reduced.
Note: In order to use the
Paint Reduce Weights Tool you must have previously used the
Reduce feature with
Keep Originals turned on so that a
polyReduce node is created for the object you want to reduce.
You do this by first selecting the polygon mesh, and then selecting
Mesh > Reduce > 
. Turn on the
Keep Original option and then click
Reduce. You then paint on the original mesh and a copy of the mesh is reduced.