An optimization process always removes polygons and the resulting mesh will be different from the original, of course. We therefore recommend that you perform a few tests with different parameters to make sure that the optimization process will not remove important details.

Optimize

Three modes are available: 

•  “No” disables the optimization process.
•  “Curvature” is based on a mesh's curved areas and this mode tries to keep them while flat areas will be removed – at least partially.
•  “Camera” analyses the mesh based on the polygons' distance to the scene's (animated) camera. Areas close to the camera will keep a high level of detail, and regions which are far away will be optimized.

(Camera) Distance

This value represents the distance between the camera and the area where the first polygons will be removed. With greater distance (= higher values) the number of polygons decreases.