The Study On Evaluation Method Of BRDF Models In Realistic Graphics Technology

With the development and application of realistic graphics technology in the fields of medical examination,geophysical exploration,virtual game design,military equipment and so on,how to generate high realistic scenes has become a hot topic at home and abroad.The BRDF model which describes the optical properties of surface material is one of the key techniques to draw realistic graphics.Different applications have different requirements for BRDF models.For example,virtual games require high efficiency of scene rendering,and realistic 3D terrain of geophysical exploration should be guaranteed.A large number of BRDF models are proposed to provide users with a variety of options.Therefore,adopting the correct evaluation method to select the ideal BRDF model with specific requirements plays a decisive role in the illumination rendering results.Based on the six properties of the BRDF model,this paper evaluates BRDF models with objective parameters and subjective vision.Firstly,the common physical parameters describing the optical properties of material surface are enumerated,and the advantages of the illumination models based on BRDF are analyzed.The representative BRDF models are analyzed theoretically and evaluated preliminarily from the principle and the intuition.Then,materials in the MERL database are classified according to the optical characteristics.In the process of fitting data of all kinds of materials,parameter optimization algorithm is used to get the optimal parameters of each model,and the objective parameters L2 norm,mean square error,peak signal to noise ratio,Frames Per Second are adopted respectively to evaluate universality,accuracy,authenticity and efficiency of each medel.Finally,the simulation platform is built to realize the light rendering of different scenes.Scene place respectively the ideal point light source and static surface light source in regular shape and uniform radiation.According to the evaluation results based on objective parameters,the BRDF model with desired performance is choosed to realize the scene simulation of point light source and surface light source.Analyze the simulation result and realize the further evaluation of the model by combining the subjective vision.