Abstract
<p>Stereo endoscopes for minimally invasive surgery are well established in different medical applications. They may reduce the intervention time due to a better visual support of the surgeon by stereoscopic viewing. Due to rather difficult image analysis conditions in surgical environments, stereoscopic cameras are usually not used for 3D measurements during conventional operations. Especially for computer-assisted surgery, a highly reliable, accurate and dense surface real-time measurement could be of high importance. For that reason, a miniaturised trinocular camera system has been developed and is presented in this paper. To process the trinocular image sequences, a rectification approach for image triplets and an efficient trinocular semi-global matching approach have been implemented. The system is evaluated using two exemplary image triplets with very different matching conditions. The results from the developed trinocular matching are compared with reference models and against the results from OpenCV semi-global block matching using the left and right stereo images only. The proposed trinocular approach consistently provides more complete and error-free point clouds. The greatest improvement due to introducing the third image is achieved without any optimisations such as semi-global matching. The proposed trinocular approach achieves at least the same result quality as the binocular approach, but allows smaller matching windows. Due to fewer arithmetic operations in three small windows than in two large ones, the trinocular analysis outperforms the binocular analysis in terms of speed.</p>