Aim: Endoscopic optical systems have unique characteristics that differentiate from other optical imaging techniques. Especially, the near-light sources cause the problem of inferring shape from shading (SfS) a complicated one. Moreover, specular and non-Lambertian nature of the intestinal tissues call for a non-traditional model. In this work we propose a robust perspective SfS model and show how it reconstructs shapes in an efficient manner for a variety of endoscopic systems.
Input Colonoscopy image
Our result 
 V. B. S. Prasath, H. Kawanaka. Near-light perspective shape from shading for 3D visualizations in endoscopy systems. IEEE International Conference on Bioinformatics and Biomedicine (BIBM), Kansas, USA. Proc. IEEE, pp. 2293-2295, Nov 2017.
 V. B. S. Prasath. Mucosal surface detection and reconstruction from endoscopic images with robust perspective shape from shading. In preparation.
 M. Visentini-Scarzanella, D. Stoyanov, G.-Z. Yang, Metric Depth Recovery from Monocular Images Using Shape-from-Shading and Specularities, IEEE International Conference on Image Processing (ICIP), Orlando, FL, 2012.