Light source position calibration method for photometric stereo in capsule endoscopy

ABSTRACT

For photometric stereo in capsule endoscopy, calibration of light source is crucial for improving the precision of surface normal estimation. Therefore, this paper presents an improved planar-mirror-based light source position calibration method: from captured images of light source and detected poses of planar mirror, light paths are retraced from camera to light source, and position of light source is triangulated with least square method. The contribution of this paper is that a refraction model of the planar mirror is employed in the retracement of light paths, thus the bias of light paths caused by refraction can be compensated and the position of light source can be estimated more precisely. The results of simulation and experiment show that the proposed method provides higher calibration accuracy than the current planar mirror-based calibration method and can improve the precision of subsequent photometric stereo-based 3D reconstruction.

GRAPHICAL ABSTRACT

Keywords:

• Light source position calibration
• photometric stereo
• capsule endoscopy
• near point light source
• planar mirror

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [grant number 61603045], and the Key Laboratory of Biomimetic Robots and Systems (School of Mechatronical Engineering, Beijing Institute of Technology), Ministry of Education, China.

Notes on contributors

Yang Hao

Yang Hao received his BS degree in Mechatronics Engineering and MS degree in Weapon Engineering from Beijing Institute of Technology, China, in 2013 and 2015, respectively. He is currently working for the PhD degree in Mechanical Engineering at Beijing Institute of Technology. His research interests include medical robot system design and robotic vision technology.

Marco Visentini-Scarzanella

Marco Visentini-Scarzanella is currently a senior scientist in the Applied Machine Learning group of Amazon Japan in Tokyo. He received the MEng degree (Hons.) in Information Systems Engineering at Imperial College London in 2007 and the Ph.D. degree in Medical Image Computing at the Hamlyn Center for Robotic Surgery in Imperial College London in 2012. He was awarded the Japanese Society for the Promotion of Science (JSPS) fellowship in 2014 and the Toshiba fellowship in 2015, under which he led projects in endoscopic navigation at Kagoshima University and at the Toshiba R&D center in Kawasaki, Japan. Subsequently, he was a staff researcher at IBM Research AI in Tokyo working on intelligent navigation for the visually impaired and activity recognition in natural environments for the elderly. His work resulted in more than 40 peer-reviewed international publications and his research interests include computer vision and machine intelligence.

Jing Li

Jing Li received the PhD degree in Mechanical Engineering in 2015 from Beijing Institute of Technology, China, and then has worked on magnetically driven capsule robots at The BioRobotics Institute of Scuola Superiore Sant'Anna, Italy. Currently, he is working on the robotic capsules, in particular, on the active capsule robots for colonoscopies in Beijing Advanced Innovation Center for Intelligent Robots and Systems. His research interests include pose control and motion planning of robots, magnetically driven endoscopic capsules, and magnetic localization strategies.

Peisen Zhang

Peisen Zhang received the BS degree in Mechanical Engineering from the Beijing Institute of Technology, China, in 2014. He is currently working for the PhD degree in Mechanical Engineering at Beijing Institute of Technology. His research interests include the design of biomedical robot platform, application of computed tomography technology, and human-robot interaction.

Gastone Ciuti

Gastone Ciuti received the Master's degree (with honours) in Biomedical Engineering from the University of Pisa (Pisa, Italy) in 2008, with a thesis entitled ”Study and development of endoscopic robot with locomotion based on the permanent magnetic field”, carried out at the Center for Research in Microengineering Lab of Scuola Superiore Sant'Anna (Pisa, Italy). Gastone Ciuti, after obtaining the PhD in BioRobotics (with honours) in 2012, was Assistant Professor in BioRobotics and, currently, is Associate Professor in Bioengineering at The BioRobotics Institute of Scuola Superiore Sant'Anna, Surgical Robotics and Allied Technologies area, and head of the Computer-Integrated Technologies for Robotic Surgery laboratory. Prof. Gastone Ciuti is co-author of more than 70 scientific publications on computer-integrated platforms and innovative devices for medical robotic intervention and treatment (more than 48 in ISI journals) and he is also the inventor of more than 10 international patents.

Paolo Dario

Paolo Dario is professor of Biomedical Robotics and director of the PhD program in BioRobotics at The BioRobotics Institute of Scuola Superiore Sant'Anna, Pisa, Italy. He is and has been visiting professor at prestigious Universities in Italy and abroad, e.g. Brown University, Ecole Polytechnique Federale de Lausanne (EPFL), Waseda University, University of Tokyo, College de France, Zhejiang University and Beijing Institute of Technology. He is also a 1000 Talents Program professor at Tianjin University (Tianjin, China). His current research interests are in the field of bio-robotics and bionics, and include surgical robotics, micro/nano devices for endoscopy, bio-inspired devices and systems, and assistive and companion robots. Paolo Dario is the author of 400+ journal publications, co-author of 50+ international patents, and co-founder of five start-up companies. Paolo Dario has been the coordinator of many large National, European and International projects. Paolo Dario received many prizes and Awards, including the 2014 IEEE RAS George Saridis Leadership Award and the 2017 IEEE RAS Pioneer Award.

Qiang Huang

Qiang Huang received the BS and MS degrees in Electrical Engineering from the Harbin Institute of Technology, China, in 1986 and 1989, respectively, and the PhD degree in Mechanical Engineering from Waseda University, Japan, in 1996. He was a research fellow with the National Institute of Advanced Industrial Science and Technology, Tokyo, Japan, between 1996 and 1999. He was a research fellow with the University of Tokyo, between 1999 and 2000. He is currently a professor with the Beijing Institute of Technology, Beijing, China. He is the director of Intelligent Robotics Institute, and the director of the Key Laboratory of Biomimetic Robots and Systems, Ministry of Education of China. Huang received the First Class Prize of the Ministry of Education Award for Technology Invention. He serves as chairs in many IEEE conferences, such as the organizing committee chair of the 2006 IEEE/RSJ International Conference on Intelligent Robots and Systems, the general chair of the 2017 IEEE International Conference on Robotics and Biomimetics, the 2018 IEEE-RAS International Conference on Humanoid Robots.