Controls the positions of vertex normals. This affects the appearance of shaded polygons.
Turn this option on so that all the normals in the calculation have a length of 1, and each one contributes equally to the average. This is the default setting.
If this option is turned off, and if you explicitly set normals where the length is not equal to 1, then the contribution of these normals to the average is weighted by the length of the normal (the new normal will be closer in direction to the longer normals).
If Normalize before averaging is off, you can keep the length of the normal that resulted from the calculation, or set the length to 1 by turning on Normalize after averaging. The length may be significant in future invocations of Average Normals. If Normalize before averaging is on, this option is disabled, since the result will be automatically normalized.