Research On Key Technologies Of Endoscopic Three-Dimensional Imaging

The traditional two-dimensional endoscopic imaging system lacks depth information,which makes it difficult for doctors to operate and position surgical instruments in minimally invasive surgery,which increases the complexity and risk of the operation.In order to solve this problem,three-dimensional endoscopic imaging technology has become a new development direction of medical endoscope technology.In this thesis,the key technologies of three-dimensional endoscopic imaging have been studied in depth,and the three-dimensional imaging of medical endoscope system is realized by the method of combining structured light and binocular stereo vision.The main research work of the thesis is as follows:（1）Aiming at the minimally invasive surgery scene with weak texture,the overall scheme of three-dimensional endoscopic imaging system based on binocular structured light technology was designed,and the theoretical model of the system was deduced,then the hardware module and software module involved in the system were sorted out.（2）The imaging model of the camera is studied,and the camera calibration method of Zhang Zhengyou was deduced,then the stereo recitification method based on the camera parameters was analyzed.Besides,according to the principle,the relevant algorithms were written,whose effectiveness was verified by simulation experiments.（3）The research on stereo matching technology was carried out,and two highprecision matching algorithms,semi-global Matching（SGM）and AD-Census,were analyzed in detail.In order to meet the needs of real-time imaging in minimally invasive surgery,an improved semi-global matching algorithm was proposed and accelerated based on CUDA.Finally,the three algorithms were qualitatively and quantitatively analyzed through the image set,and the results show that the improved matching algorithm can perform faster and higher-precision matching.（4）The speckle pattern generated by computer simulation and a projector are used to form a structured light system,then two monocular endoscopes were combined to build a three-dimensional endoscope experiment platform,besides,the software module was compiled.（5）Based on the experimental system,an experimental study on three-dimensional imaging of weakly textured objects was carried out.Several geometric plaster models lacking texture and human palms were selected for three-dimensional reconstruction experiments,and the results show that the system can quickly obtain better reconstruction effect.Besides,the system accuracy was verified based on the ladder model,and the relative measurement error is 0.64%,which shows that the whole system can achieve high-precision three-dimensional reconstruction.