Real-time Human Heart Model Rendering Based On Screen Space Subsurface Scattering

With the development of physics-based rendering and the improvement of GPU computational power,real-time rendering technology for 3D display has been widely used in computer-aided surgery.Subsurface scattering technology is used to render materials like human tissues and organs that are not completely transparent inside,but also have semi-translucent,water-bright capsule,which makes the performance realistic.In this paper,the bidirectional reflection distribution function and subsurface scattering technology rendering theory are combined,and the Jensen dipole theoretical model is improved,and the optimized bidirectional scattering surface reflectance distribution function(BSSRDF)is obtained.The subsurface scattering rendering algorithm improved by this function has been used to render the heart model with excellent rendering effect.The research contents include:(1)According to the three-layer structure of the endocardium,epicardium and myocardium and the interaction between light and biological soft tissue on the surface of the human heart,the analysis of the heart illumination model can be decomposed into surface highlights,surface diffuse reflection,internal single scattering and internal multi Sub-scattering is the basic theory related to the rendering of heart subsurface scattering.(2)The definition and properties of subsurface scattering and the theoretical calculation formula of BSSRDF function are elaborated,and five subsurface scattering models are compared and analyzed: dipole model,multi-dipole model,quantitative diffusion model,pre-integration model,light diffusion The advantages and disadvantages of the model,and compare the rendering effects of different models.(3)Improve and optimize Jensen’s dipole theory model: through theoretical research and influence ratio,BRDF can be used to approximate single scattering;by introducing the Manhattan distance algorithm to calculate the shortest distance,the calculation speed of multiple scattering can be increased.The optimized and improved subsurface scattering algorithm is used for real-time heart model rendering to achieve the expected soft tissue semi-transmission effect.Compared with the BRDF rendering algorithm and the Unity 3D platform’s own rendering algorithm,it has obvious advantages in rendering speed and rendering effect.(4)Design and implement a virtual heart surgery training simulation platform to subjectively and objectively evaluate rendering effects.For objective evaluation,the data fitting curve of this algorithm is compared with the Monte Carlo discrete rendering fitting curve.The similarity between the two is high,indicating that the algorithm is successful.Subjective evaluation uses the designed evaluation questionnaire to evaluate the rendering effect.Through the actual operation of the platform,a series of questions are scored,and the final score is compared to find that the algorithm rendering accuracy of this paper is the highest.