A 3D Laparoscopic Imaging System Based on Stereo-Photogrammetry with Random Patterns

In this paper, we propose a novel 3D laparoscopic imaging system based on stereo-photogrammetry which is assisted by projecting patterns on the tissue surface. The proposed laparoscopic imaging system has three optic channels, two of which are responsible for stereo vision feedback and the other one is used for coded structured patterns projection. The projected patterns provide the robustness to homogeneous tissue surface since they add more features that can be relied on in the stereo matching. Image fiber bundles (100k pixels) and Gradient-index (GRIN) lenses are utilized to facilitate the remote image acquisition and miniaturization of the laparoscopic probe. Moreover, we adopt a digital micromirror device (DMD) and high-speed cameras to achieve fast pattern switching (up to 4 kHz) and high frame rate image acquisition. The system configuration allows for implementation of the time multiplexing pattern codification strategy in the 3D laparoscopic imaging system to enhance the reliability and resolution of the 3D surface reconstruction. A prototype is established, and various experiments are conducted. Comparative experimental results prove the advantages of our system design. The static and dynamic 3D reconstruction results validate the performance of the proposed 3D laparoscopic imaging system quantitatively and qualitatively.