Effects of different coating materials on three-dimensional optical scanning accuracy

Abstract

The processes of three-dimensional optical scanning depend on the reflection of the surface to be digitized. To scanspecular or translucent surfaces, it is necessary to apply a coating material which interferes with the accuracy of thethree-dimensional measurements. This study proposes the use of gold, silver, platinum, and carbon by sputtering to coatthe surfaces to be scanned. The effects of these materials on the accuracy of the three-dimensional scanning were evalu-ated and compared with those of two frequently used materials, namely, talc and non-aqueous wet developer for pene-trant testing. To verify the resulting geometric variations, specimens were scanned before and after the application ofeach coating material. The results showed that the intrinsic errors of the three-dimensional scanning process, such asthe registration of several point clouds, can have more significant effects than the coating material used. Measurementstaken from a single point cloud showed dimensional tolerances of approximately 0.01mm for gold, platinum, and carboncoating. These coatings offer significantly higher accuracy than the traditionally used developer and are suggested foraccurate three-dimensional scanning of specular and translucent surfaces.