Opaque Object’s Reflectance Modeling Technique Based On Blinn Model

Opaque objects’ reflectance data reconstruction is one of the most important issues in the Virtual Reality. Real objects’ material reconstruction can improve the sense of reality and simulate shading changes under different illuminations. It is widely used in the areas of game, video and the digital collection of the culture heritage.The current method of the material reconstruction usually uses an albedo meter to measure the material features directly. The main devices include goniometer, detector, illuminant and computing system. These methods need expensive equipments and take a lot of time. This paper implements a material calculation system which uses a3D scanner to get3D model and uses camera to obtain the texture pictures under different illuminations to calculate the material parameters of the model. When the material parameters of the model are obtained, we implement the relighting of the model under other viewpoint or illumination.Firstly, we use a3D scanner to get3D model. Then we use texture mapping to get the vertex color instead of obtaining the vertex color by the3D scanner because when using the3D scanner, it will bring other light sources. Then we use steel ball to get the illumination direction. After we obtain the texture pictures, we use the corresponding points between the surface of the3D model and texture picture to calculate the texture mapping result. Then we use self-occlusion algorithm to get rid of the redundant texture.Then, we compare different kinds of the Bidirectional Reflectance Distribution Function model, and choose the Blinn model to represent the material of the model. Next, we promote an algorithm to calculate the Blinn parameters of the model according to the specified highlight points. With the highlight points between the3D model and texture picture, we can calculate the viewpoint of the picture, and with the illumination direction, we can use the nonlinear optimization to calculate the highlight parameters. Then, we can calculate the diffuse parameter of the model by weighted algorithm based on different texture pictures. Finally, we use the occlusion algorithm to calculate the shadow and render the new effect of the model under new viewpoint and illumination.