Simultaneous measurement of 3-D shape and color of objects

Procedures for measuring the three-dimensional shape of objects using fringe projection are well known for many years. Those systems are suitable for instance for quality control and reverse engineering. For recognition and visualization of objects it's necessary to obtain the shape and also the color and/or the texture of the object's surface. Furthermore, in quality control like defect identification the color information of the surface can be useful. But the use of color cameras to capture all data has the lack of lower resolution or lower frame rates and may cause problems while measuring the shape (with one chip cameras) because different colors are recognized by different pixels looking on different points of the surface. This will cause measurement errors. Here we propose a method basing on the fringe projection technique, which is able to determine the 3-D co-ordinates as well as the color at all measurement points while using only black/white cameras. The main advantage of this method is that color and shape are obtained together with the same (high resolution) camera and that the shape and color information are put together without any matching procedures and are obtained within the same measurement. For this the object is illuminated within the same projection sequence with non structured full frame colored light, e.g. red, green, blue and the well known fringe patterns. As the final result one gets at each measurement point three co-ordinate values containing the position and three-color values containing the real color.