Research On The Simulation Method Of Skin Surface Deformation For Virtual Puncture

The virtual surgery system is widely used in medical filed.It is the combination of virtual reality technology and computer graphics,which can provide medical staff with operation plan and operation training,etc.Puncture is widely used in daily medical and diagnosis,the puncture needle penetrates the skin to reach the target position,and implement the operation of injection and sampling,so skin deformation simulation in virtual puncture is a critical technologies.Skin deformation in virtual puncture should ensure both stability and realism in the process of simulation.In addition,it is necessary to ensure the real-time performance of skin deformation in virtual puncture to meet the real-time human-computer interaction requirements.Therefore,real-time,realism and stability are the three criteria for measuring the quality of skin deformation simulation in virtual puncture.Based on the above requirements,the basic work and the results of this research,which are based on the above requirements,described as follow:(1)The skin deformation physical model and geometric model of skin were established.The biomedical properties of the physical model of skin deformation were analyzed,and mass-spring model was selected as the physical model of skin deformation.In order to ensure the simulation stability of skin deformation in virtual puncture,the skin geometric model was established by using the tetrahedral mass-spring topological structure information that generated by TenGen.It also defines a file format for storing the data of skin geometric model to facilitate subsequent research.(2)Study on the rapid numerical solution algorithm of skin deformation dynamics model in virtual puncture.Based on the skin deformation dynamics model of mass-spring physical model,a numerical solution method of optimize implicit Euler is established.We introduced virtual spring related auxiliary variables to solve optimize implicit Euler,and then rewrite it as the minimization problem of fast numerical solution by using block coordinate descent.At the same time,this method ensure the real-time performance of skin deformation in virtual puncture.(3)Optimization the realism of skin deformation in virtual puncture.Because the traditional mass-spring physical model has lack of realism in the virtual puncture simulation method of skin deformation,it is necessary to optimize the realism of skin deformation in virtual puncture.According to the insufficiency of wrinkles in skin deformation,a method of Poisson deformation was proposed to improve the sense of reality.First,we used geodesic line to detennine the skin deformation range.When the skin model is defonned by external forces,the Poisson deformation method is applied to the skin model in the range of deformation to generate skin wrinkles.Because the skin deformation is not smooth between the deformation area and non-deformation area,the method of volume preservation is proposed to improve this deficiency.In the simulation of skin puncture,the skin volume information was maintained by volume constraint,and local deformation was maintained by weight vector distribution.In this way,the smooth transition between the skin deformation region and the non-deformation region was achieved.Finally,this paper design and implement prototype virtual puncture system of skin deformation,the algorithms and visualization of each module are integrated,the experimental results and analyses are given.Experiments show that the algorithms described in this paper can guarantee the realism,stability and real-time performance in virtual puncture of skin deformation,which is great significance to the study on the skin deformation for virtual puncture.