3D reconstruction of tongue surface based on photometric stereo

In the objective research field of traditional Chinese medicine (TCM) tongue diagnosis, 2D tongue image is regarded as the research object for feature extraction and analysis in most current methods. However, 2D tongue image always can not visually express detail information of tongue 3D surface, such as lingual papilla, prick and fissure of tongue. It brings certain limitations to perceive real tongue surface. It is limited for the doctor to give accurate diagnosis. To solve this problem, a method to reconstruct the 3D surface of tongue based on photometric stereo is proposed. First, the surface normals and texture reflectance are obtained using photometric stereo technology in this paper, then calculate the depth values of tongue surface, and generate 3D depth map. It has been proved that the method is viable through lots of experiments and doctors may observe the 3D information of tongue surface from multiple perspectives. Detail information of tongue surface also may be expressed quantitatively and visually.