Real-time Depth Of Field Rendering Based On Mipmap And Soft Shadow

The effect of depth of field simulates how human see real scenes,that is,the object in the focus area is clear,and the object in other areas is blurred.Soft shadow is also very realistic simulation of the shadow effect in nature,and there is a certain transition between shadow area and bright area,besides eliminating the sawtooth in shadow edges.While rendering,depth of field and soft shadow can increase users' immersion,making it more realistic,especially in the game scenes and virtual reality.A real-time depth of field rendering system based on mipmap and soft shadows is designed.Mipmap technology can blur textures,so it can be used to simulate the depth of field effect.In fact,the depth of field blur is caused by the circle of confusion.According to the principle of optical imaging,the blur effect of the circle of confusion is similar to Gauss blurring,and the standard deviation of the Gauss function is directly proportional to the circle of confusion diameter.The relationship between the Gauss standard deviation and the mipmap level can be obtained through experiments,and then the relationship between the circle of confusion diameter and the mipmap level can be obtained.In order to prevent the leakage of light intensity,anisotropic interpolation is used for mipmap.For PSSM algorithm,the camera visible area is divided into three areas: focus region,foreground region and background region,and then VSM algorithm is used corresponding to the three shadow,getting the depth values and the square of depth values,and the three shadow maps are filtered to different degrees.Finally,according to the circle of confusion diameter,the shadow coefficients for the screen pixels are filtered by Gauss filter.Thus,we can get a more realistic soft shadow effect.Mipmap technology is used to simulate the depth of field effect,PSSM and VSM are used to generate soft shadows.Through the analysis of the experimental results,the effect is well enough both in time and reality.