A Research Of Non-Photorealistic Rendering Techniques On Mobile Devices

With the popularization of the network and globalization, the manufacturing industries are struggling under the pressure of competition. Meanwhile, with the rapid development of the mobile devices, the problem of how to actualize the discussion of design process through the mobile devices and accelerate the process of the product development is a crucial issue due to the importance of information discussions. Because non-photorealistic rendering is better than photorealistic rendering in delivering some specific information, it will be more helpful for collaborative discussion of the designing if we use non-photorealistic styles to render models on mobile devices.Firstly, the importance of non-photorealistic rendering in collaborative discussion of the designing is described and the characteristics, main techniques and relative researches of non-photorealistic rendering are analyzed. On the basis of analyzing the characteristics of mobile devices and the research status about graphics technology on mobile devices, the importance of researches about non-photorealistic rendering on mobile devices is emphasized.Then, a framework of server/client system is presented and the system modules are analyzed. The server is responsible for providing some functions including constructing and transforming a model, abstracting and conversing the data from the model. The clients are responsible for parsing the data and rendering the model in non-photorealistic styles. The main flow of our system is described after analyzing the functions of each module.Due to the resources limitation of the mobile devices, incapability in dealing with the 3D graphics, and the use of the wireless network, our system adopts line-frame to represent models, converses the three-dimensional lines into two-dimensional lines to render in non-photorealistic styles. This method can reduce the data through the network, cut down the transmission delay caused by the network bandwidth, eliminate the over-dependence upon the hardware of the mobile devices, and make it possible to develop a real-time interactive server/client system. The interactive data between the server and the clients are formatted by XML, which can improve the reliability, transplantable ability and extensibility of our system.In this paper, we lay great emphasis on analyzing the characteristics of hand-draw lines and representing the lines in different non-photorealistic styles, and draw a comparison among different representations. In the proposed system, the XMLlanguage is used to define a set of elements and attributes, clearly express the data and the rendering styles of the models, and support the multi-style expression in a model that its styles can be flexibly controlled, edited and extended by the client users.Finally, the implementation of a prototype system is described and several non-photorealistic line-drawing algorithms are proposed and implemented. The clients can flexibly control the styles including the shape, width and thickness by freely changing the parameters of them and support multi-style rendering in a model, which is extremely convenient for the mobile device users to efficiently deliver the visual information and design intentions.