Optical evaluation method for granular materials e.g. stone

摘要

The method involves using a CCD camera (2) which is positioned vertically above a flat face (5) on which the material to be identified is placed. The camera is at the same height as a first lighting source (1), also vertical to the material. A picture of the surfaces is transmitted to a picture analyser. The first light is switched off and a second light-source (3) at 45 degrees to the material is used to illuminate the material, giving a shadow on the flat face. The material is also photographed and processed. A third oblique lighting source (6) is used, at 90 degrees to the previous lighting, and the material is photographed and processed to silhouette the particles.