Research And Implementation Of Petal Realistic Rendering Algorithm Based On Micro-surface Reflection And Sub-surface Scattering

Realistic rendering is a key research issue in computer graphics.The most common plants in nature is the focus of realistic rendering.With the development of the GPU computing power and the development of game industry,the requirements for scene rendering,especially outdoor natural scenes,are becoming higher and higher.More and more realistic renderings begin to pay attention to the detailed description of the organs or tissues of plants.Flowers are translucent material plants with rich colors,prominent micro-surface details and strong subsurface scattering.As a key component,petals are an important part of the interaction between flowers and light.Realizing the realistic rendering algorithm of petals,rendering the real effect of petals under the action of light and expressing the characteristics of translucent material is a difficult problem of realistic rendering.It is of great significance to the research of realistic rendering and the rendering of translucent material objects.According to the structure of petals and the illumination process of material characteristics,this paper presents a realistic rendering algorithm of petals,including illumination calculation,shadow rendering and transparency rendering algorithm.There are light reflection and subsurface scattering processes on the surface and inside of petals respectively.There are few light models describing the two complex processes of petals in existing studies.A complete model for calculating the illumination of petals on the light-oriented and back-lit surfaces is proposed in this paper.In the existing research,people often use the traditional light calculation model to render the surface reflection.In order to show the micro-surface details and material characteristics of petal surface,a light model based on Cook-Torrance micro-surface reflection is proposed to calculate surface illumination in this paper.At the same time,it innovatively proposes the use of bloom post-processing to render the high-light effect of petals.For the subsurface scattering process,the existing research is usually implemented by dipole approximation simulation and prediction.Based on the existing research results,an improved real-time rendering method for multi-dipole approximation calculation and a sub-surface scattering calculation model between two layers of surfaces are proposed in this paper,which does not require the prediction process.Finally,in order to improve the authenticity of petal rendering,an improved shadow rendering algorithm based on Gaussian Blur and Percentage-closer Filtering is proposed,and a petal transparency calculation algorithm based on dual-depth separation algorithm is proposed.This paper use Open GL and GPU-based shader programming language GLSL to realize the petal realistic rendering algorithm.The algorithm is extended to other objects with the same material characteristics such as leaves to verify the correctness and versatility of the algorithm.