Research on highly dynamic 3D measurement method based on RGB color fringe projection

Metal parts with highly dynamic areas often appear in industrial production measurements. However, if the traditional fringe projection technique is used to project fringe onto the surface of these metal parts, the light energy will be excessively concentrated and the image will be saturated, resulting thus in the loss of fringe information. To effectively address the high reflectivity problem of the object under test in fringe projection, background normalized Fourier transform contouring was combined with adaptive fringe projection in this work and a new method for performing highly dynamic 3D measurements was proposed. To reduce the number of the acquired images by the camera, a monochromatic fringe of different frequencies was put into the RGB channel to make color composite fringe, and then a color camera was used to acquire the deformed color composite fringe map. The images acquired by the color camera were then separated into three channels to obtain three deformed stripe maps. The crosstalk was also removed from these three images, and the 3D shape of the object was reconstructed by carrying out Fourier transform contouring with background normalization. From our experiments, it was demonstrated that the root mean square error of the proposed method can reach 0.191 mm, whereas, unlike the traditional methods, the developed method requires four images.