Xinan Sun1,2, He Su3,4, Jinhua Li1,2, Shuxin Wang1,2. 1. Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, 135 Yaguan Road, Tianjin, 300350, China. 2. School of Mechanical Engineering, Tianjin University, 135 Yaguan Road, Jinnan District, Tianjin, 300350, China. 3. Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, 135 Yaguan Road, Tianjin, 300350, China. suhe@tju.edu.cn. 4. School of Mechanical Engineering, Tianjin University, 135 Yaguan Road, Jinnan District, Tianjin, 300350, China. suhe@tju.edu.cn.
Abstract
PURPOSE: Stereo vision can provide surgeons with 3D images and reduce the difficulty of operation in robot-assisted surgery. In natural orifice transluminal endoscopic surgery, distortions of the stereoscopic images could be induced at different observation depths. This would increase the risk of surgery. We proposed a novel camera to solve this problem. METHODS: This study integrated the camera calibration matrix and the geometric model of stereoscopic system to find the cause of distortion. It was found that image distortions were caused by inappropriate disparity, and this could be avoided by changing the camera baseline. We found the relationship between camera baseline and observation depth with the model. A variable baseline stereoscopic camera with deployable structure was designed to achieve this requirement. The baseline could be adjusted to provide appropriate disparity. RESULTS: Three controlled experiments were conducted to verify the stereo vision of the proposed camera at different observation depths. No significant difference was observed in the completion time. At the observation depths of 30 mm and 90 mm, the number of errors apparently decreased by 62.90% and 51.06%, respectively. CONCLUSIONS: The significant decrease in number of errors shows that the proposed camera has a better stereo vision than a regular camera at both small and large observation depths. It can produce more accurate stereoscopic images at any depth. This will further improve the safety of robot-assisted surgery.
PURPOSE: Stereo vision can provide surgeons with 3D images and reduce the difficulty of operation in robot-assisted surgery. In natural orifice transluminal endoscopic surgery, distortions of the stereoscopic images could be induced at different observation depths. This would increase the risk of surgery. We proposed a novel camera to solve this problem. METHODS: This study integrated the camera calibration matrix and the geometric model of stereoscopic system to find the cause of distortion. It was found that image distortions were caused by inappropriate disparity, and this could be avoided by changing the camera baseline. We found the relationship between camera baseline and observation depth with the model. A variable baseline stereoscopic camera with deployable structure was designed to achieve this requirement. The baseline could be adjusted to provide appropriate disparity. RESULTS: Three controlled experiments were conducted to verify the stereo vision of the proposed camera at different observation depths. No significant difference was observed in the completion time. At the observation depths of 30 mm and 90 mm, the number of errors apparently decreased by 62.90% and 51.06%, respectively. CONCLUSIONS: The significant decrease in number of errors shows that the proposed camera has a better stereo vision than a regular camera at both small and large observation depths. It can produce more accurate stereoscopic images at any depth. This will further improve the safety of robot-assisted surgery.
Authors: Mingxing Hu; Graeme Penney; Michael Figl; Philip Edwards; Fernando Bello; Roberto Casula; Daniel Rueckert; David Hawkes Journal: Med Image Anal Date: 2010-12-10 Impact factor: 8.545