The quality of CAD models are highly varying depending on the originating CAD system and the maner in which the CAD system facilities is employed. The structuring of a model into surface patches is often defined more from the modeling history than the actual shape of the object. Furthermore, translation of the model from the proprietary format to a standard exchange format like STEP or IGES can produce errors in the model representation.

A number of standards for CAD qualities exist. The following is a subset of quality tests fetched from these standards:

• Short curves and edges
• Small surfaces and faces
• Sliver faces
• Gaps between faces
• Non-smooth models
• Edges and vertices too distant from the corresponding face
• Acute faces and edges
• Embedded curves and surfaces
• Self intersections
• Degenerate surface boundaries
• Small curvature radius
• Folded surfaces, oscillations
• Bad knot distribution