this invention relates to electro - optical sensing of form type and other defects on surfaces such as sheet metal or plastic panels . method and apparatus are disclosed for detection and quantification of defects such as dents , creases , low spots , flat spots , etc . which are a result of the manufacturing , material handling and assembly process . surfaces of interest are generally those of automobile body panels , , refrigerator panels , furniture panels , and aircraft panels . similar applications exist to dies and other formed metallic or plastic parts . both automatic and human visual methods and apparatus are disclosed . the disclosed invention is also effective on paint defects such as orange peel encountered in automotive and other applications . assemblies of panels , such as car bodies may also be inspected using the invention , and both fixed and moving sensor versions are disclosed .