Parallax correction of texture image in fringe projection profilometry

In fringe projection profilometry, the measurement system generally consists of a projector for casting fringes onto a measured object and a monochrome camera for capturing the deformed fringe patterns. In addition to these components, we can add a color camera for capturing the texture of the object simultaneously. For implementing texture mapping on the reconstructed three-dimensional (3-D) surface, the parallax between the views of the texture camera and the measuring camera has to be corrected. For this purpose, we analyze the geometry of the fringe projection system with a color texture camera and further suggest a system calibration method. Using this method, the corresponding relationship between the texture and the 3-D data and the mapping relationship between the depths and the fringe phases are determined simultaneously, so that the duration time for the system calibration implementation is saved. The data processing with this method is of a low computational complexity because it involves only linear minimizations. Using the calibration results, we can transform the texture image from the view of the color camera to that of the measuring camera and precisely map it on the reconstructed object surface. Experimental results demonstrate that this method is effective in correcting the parallax of the texture image.