Research On Key Approach Of Hybrid Real-time Rendering

After decades of development,the rasterization-based real-time rendering pipeline has overemphasized the simplification of the lighting model,and the algorithm is limited by the parallel GPU architecture.In recent years,it has gradually entered a bottleneck.At the same time,in August 2018,the Turing architecture GPU packaged supporting fast parallel ray tracing was officially released.Real-time ray tracing seems to be a savior for real-time rendering.However,under current GPU computing capabilities,high-sample-rate Monte Carlo path integral rendering similar to offline rendering cannot meet real-time requirements.Combining the essence of real-time ray tracing and rasterized rendering to form a hybrid rendering pipeline is the most clear research direction at present.Based on the simplified idea of rasterization,lighting calculations are decomposed into direct lighting,reflection,and indirect diffuse reflection.For each part,ray tracing is used to generate reflective textures,indirect diffuse reflections and shadows at low sampling rates,and combine filters to eliminate high-frequency noise.The rendering algorithm based on ray tracing fundamentally improves the authenticity of rendering.Each part of the pipeline can flexibly balance the effect and efficiency according to the combination of different sampling rates and filters.At the same time,the hybrid rendering pipeline makes great use of the correlation of the data,uses delayed rendering to generate GBuffer instead of Prime Ray Tracing,and uses the first few frames of the image as additional time domain information in the subsequent denoising process to ensure efficiency A very good picture effect was obtained at the same time.In this paper,based on the simplified idea of rasterization rendering for the lighting model,the lighting model is decomposed into three parts: direct lighting,reflection,and indirect lighting.Each part is rendered using a ray tracing algorithm at a low sampling rate.The main work of this article is as follows:1.Achieved direct lighting rendering based on ray tracing.Based on the BRDF distribution of GGX,this paper has simplified the direct light rendering of light sources and polygonal light sources.At the same time,a real-time shadow rendering system that supports hard-edged and soft shadows has been implemented at a sampling rate of 1 ray / pixel.On this basis,and using the idea of checkerboard rendering to improve,further improve the rendering quality.2.In the reflection part,the reflection sampling is performed at a sampling rate of 0.25 ray / pixel,and a high-resolution reflection texture reconstruction algorithm is realized through the interaction of the sampling points of adjacent pixels.Finally,the additional 1 ray / pixel visibility light sampling improves the accuracy of the reconstruction and achieves high-quality real-time reflection rendering.3.Indirect lighting,this paper improves the LPV method.A 16 * 16 * 8 probe array is distributed in the scene,and the indirect lighting information of the scene is obtained using 256 ray / probe.When rendering an object,the surrounding eight Probes are used for sampling to achieve high-efficiency indirect lighting rendering,while solving the problems of insufficient dispersion distance,light leakage and dark leakage of the LPV method.4.Using TAA + SVGF to process the light and reflection images before processing,to filter out the high frequency noise generated at a low sampling rate.Smear occurs when the camera and light source move when TAA resampling the reflection texture.Based on the improvement of the plane mirror model,this article further uses the thin lens model to improve the smear problem of the surface reflection texture.5.Based on the appeal algorithm and combined with the latest rendering engine implementation,DX12 is packaged,a high-performance renderer that supports multithreading is completed,and the scene management algorithms of Grid and BVH are encapsulated.Using this renderer,a complete test experiment was performed on the scene,and satisfactory results were obtained.