Study On Key Algorithms Used In Virtual Exhibition System

Virtual exhibition technology has become one of the hot research topics in recent years, along with the blooming of E-Commerce. There are three key problems in virtual exhibition system: how to improve the exhibition effects, how to reduce the computation and storage requirement and how to provide more convenience. Some efforts have been performed on these issues in this dissertation. The main contributions of this dissertation include:A new color constancy algorithm for uncalibrated images: The inflection of the incident light has to be removed during the course of virtual exhibition. Traditional color constancy algorithms can only handle the images which intensities are linear with the scene reflected illuminations. Therefore they are not practical. In this dissertation, we provide a new color constancy algorithm which can handle uncalibrated images and is free of camera and shot parameters. Anisotropic Mean Shift analysis is employed to cluster color signals form one uniformly colored surface. The clustering result gives the variation trend of chromaticity. The estimation of the chromaticity of the incident light is calculated on the chromaticity plane. A robust framework is designed to deal with the images have a few uniformly colored surfaces. Experiments show that our algorithm can get a good estimation and be independent on camera and shot parameters.A new color substitution algorithm based on reflecting component decomposition: a color substitution algorithm is needed when the materials of products are changed in a virtual exhibition system. Traditional color substitution algorithms just keep the brightness distribution on the object area unchanged. Therefore the substituted result is not realistic. The algorithm given in this dissertation utilizes the physics reflectence model. Therefore it can provide more realistic effects. First we use a novel projection method to decompose the reflecting components. Then a set of linear parameters are constructed to eliminate the dependence with the original color. At last, we use these parameters to do substitution. Experiments show that our algorithm can provide very realistic results. Comparing with other reflection decomposing methods, our method saves a lot of computation. Because the decomposition is performed only once, the substitution speed is very fast.A block based texture mapping method: texture mapping is a key problem during the materials changing course. Traditional texture mapping algorithms aredesigned for 3D models only. Therefore; they need a great deal of computation and storage. In this dissertation; we provide a block based texture mapping method. It can simulate the texture direction on the product surface very well. First; user divides the object area into several texture blocks. Then the texture directions of each block are defined. Texture coordinates are calculated according with the input information. The texture continuity and smoothness are ensured. To make the result more realistic; the depth of field effect can also be simulated. Experiments show that our method can simulate the texture strikes on various products surfaces. As our method uses only one image; it saves a lot of storage and computes very fast.A grid based texture mapping method: The surfaces of textile products; clothing especially; have very complex shapes. It is very hard to model and render textile products. Therefore 3D texture mapping is not practical for virtual exhibition system. A grid based texture mapping method is developed to handle this issue. Only a few texture frame lines needs as inputs. Then the method will construct a texture grid. A set of tools is provided to help users adjust the grid neatly. Therefore users can simulate gauffers; folds and so on. Experiments show that our method can provide very realistic effects. It is convenient to use and very suitable for virtual exhibition system.Based on the algorithms described above; we developed two applications. One is a virtual exhibition system for textile products: ShowMaster. The core of this system includes color substitution and block based texture mapping. It provides several modules such as information management and security. Another one is a customized show system: EasyShow. It is developed on mobile platform. The core of this system includes color substitution. EasyShow has been integrated in an intelligent mobile phone. It implements the integration of capturing; processing and distributing and has great business potential.