Acquisition system for three-dimensional surface texture of asphalt pavement based on digital image processing

In order to make an objective and true evaluation on three-dimension surface texture of asphalt pavement, an acquisition system for surface three-dimensional texture of asphalt pavement was developed based on the digital image processing. First, the classical Lambertian diffuse model was used to obtain three red, green, blue images. Then photometric stereo method was employed to calculated the surface gradients in x and y directions with the reflection intensity of three images. Finally the Frankot-Chellappa global integration algorithm was applied to making the Fourier transformation of the gradients. Thus the heights were obtained and the surface texture was reconstructed. The results indicate that the accuracy of height value obtained by the acquisition system is 0.0001 mm, which meets the requirement for analysis of texture depth; the correlation coefficient between the results of this system and the traditional sand patch test is 0.8875, which demonstrates that this acquisition system is practical.