Study Of Real-time Interactive Algorithm Of Virtual Orthognathic Surgery Based On Bone Saw

The research and development of virtual surgery simulation system involves many cross disciplines,including imaging,image processing,human-computer interaction,computer graphics,mechanical dynamics,and medicine.Currently,there are still problems such as deformation calculation feedback frequency and low refresh rate of force feedback algorithm.In view of the problems of visual and tactile feedback in virtual cutting operations of bone saws,this paper focuses on three-dimensional tissue modeling,collision detection algorithms,real-time reconstruction of sawing surfaces,and force model technologies,and solves the construction of multi-modal three-dimensional models,real-time For collision detection,real-time reconstruction of the sawing surface and force interaction,a virtual orthognathic surgery simulation system based on bone saw-based reduction of the nandibular angle is implemented that integrates visual and haptic rendering.First,based on the three-dimensional tissue modeling technology,a multi-modal 3D skull data modeling method was proposed.The skull data model is decomposed into internal voxel model and external mesh model.Each pixel of the CT image is used as the interior voxel of the skull.The outer layer of skull uses Marching Cube method to extract the iso-surface in the voxel.Grid,which combines volume data and triangle mesh data in rendering and interaction.Secondly,a bone saw-based real-time cutting and reconstruction algorithm is proposed to solve the problem of continuous visual feedback in the virtual surgical system.The path of the saw blade is detected in collision with the cubic element within a certain period of time,and the collision cube is extracted through a discrete distribution point to achieve visual real-time feedback.In view of the difficulty in assessing the sawing effect in the real operation,combined with the accurate collision point position on the edge of the cube,the Marching Cube method is used to realize real-time reconstruction of the sawing surface.Finally,based on the mechanical properties of the high-speed operation of the bone saw,a haptic interaction model of sawing force feedback was created.For the physical characteristics of bone saws,each saw tooth is divided into several small cutting units,and it is determined whether each cutting unit is immersed inside the voxel,and the force in the x,y,and z directions on each cutting unit is separately calculated,and finally accumulated.The force of the bone saw is obtained and fed back to the operator via the haptic device.The refresh rate of force sense reaches 1000Hz,which guarantees the continuity and robustness of force sense while ensuring the authenticity of force-sensing interaction.Through the evaluation and verification of the virtual plastic surgery system,the virtual orthognathic surgery training system developed in this paper provides the trainee or student with a realistic and repeatable operation training platform that satisfies the real-time requirements of visual and tactile feedback.