Physically Based Atmosphere Rendering

The atmosphere is an important component of the Earth's environment,and when rendering outdoor scenes,the quality of the atmosphere rendering plays an important role in the final visual effect of the entire scene.One way to render the atmosphere is to map the skybox texture to the entire sky using texture mapping techniques.However,this static sky effect is lacking in realism and cannot change dynamically with the change of solar zenith angle.Therefore,to improve the realism of outdoor scene rendering,a rendering method for accurate rendering of the earth's atmosphere is needed.In this thesis,a physically based atmospheric rendering method is implemented.The method is designed for GPU parallel computing architecture,which calculates the energy of light entering the viewpoint after scattering in the atmosphere by modeling the energy change of light propagation in the atmosphere and applying the volumetric rendering theory to achieve an accurate atmospheric rendering.Meanwhile,by studying the characteristics of clouds within the atmosphere,this method uses noise textures to simulate cloud shapes and distributions,and uses light stepping techniques to calculate the lighting of clouds to obtain a better quality of cloud rendering.This method also improves the efficiency of cloud rendering by reusing historical rendering results to meet the requirements of real-time rendering.Finally,this method combines the atmospheric scattering effect and the dynamic volumetric clouds to achieve a dynamic atmospheric rendering effect and improve the sense of reality of outdoor scenes.When integrating the method implemented in this paper in outdoor scenes rendering,it is not only possible to achieve atmospheric effects that dynamically change with the solar zenith angle and provide dynamic ambient lighting for objects in the scene,but also to simulate the visual effects under different pollution levels and change the shape and distribution of clouds by respectively adjusting atmospheric and cloud parameters.This method can meet the requirements of real-time rendering and improve the sense of reality of the rendering system.