GEOMETRY AND CAD / FIELD NOTE 12
Why Surface Normals Matter on Curved Panels
The surface normal identifies the face direction at a point. Reversed normals can confuse which side receives a finish, which way an offset is applied and which direction a returned edge projects.
What to check on your project
Mark the visible side on the elevation and in the model. Check normals after export and review an offset section near a boundary. Keep face and back references distinct on inspection drawings.