Polygons > Repair Normals repairs a confusion between front and back caused by the surface wrap of a noisy point object. If surface wrap creates a polygon with front-side and back-side shading on a single side of the object, use this function to detect and delete the triangles that caused the surface wrap to be imperfect.
The controls are:
Length - specifies the aggressiveness of detection. A lower number causes precise but widespread detection and correction, and a higher number may connect offending polygons into contiguous regions that may include a few “good” polygons.
OK button - deletes offending triangles and stores the repaired polygon object to the Model Manager.
Cancel button - closes the dialog without repairing normals.
To repair a model with unoriented polygons:
Click Polygons > Repair Normals. The polygons with flipped normals appear in a different color than other polygons.
Adjust the Max Length if necessary.
Click OK. The normals are automatically repaired.
Repeat if necessary.