Combining encoded structured light and photometric stereo for underwater 3D reconstruction

Surface normal maps created by photometric stereo allow for high-quality rendering from certain viewpoints, even when the resolution of original images is low. However, the lack of constraints between multiple disconnected patches, the frequent presence of low-frequency distortion, and some actual conditions often lead to a bias during the photometric stereo reconstruction using direct integration. In this paper, we therefore present a hybrid method, which exploits the depth information that the encoded structured light system produces, in order to correct the photometric stereo bias. On the other hand, this method retains the high-precision normal information. Our experimental results show that the proposed method can not only recover high-frequency details but also avoid, or at least reduce, the low-frequency bias. In particular, the error that our method generates in the underwater environment is tolerant, even in the case that high turbidity values occur.