Internet-based Multi-projection Display System Software Architecture And Implementation

With the rapid development of projection display technology, building large-format multi-projector display systems has become a great concern in research area. Multi-projector display technology has been considered to be an important way to easy the conflicts between the growing demands of high-resolution display screen and the limited resolution of a single display. Large-format multi-projector displays have made wide applications in the areas of scientific visualization, collaborative working, conference system, education and entertainment.During the building process of multi-projector display system, the primary task is to calibrate the projector's output image to achieve seamless image on the screen. The major research work of most domestic and foreign institutions for multi-projector display system includes geometric correction and color correction. Commercial software tools have the structure of a single projector corresponding to a single display device, which does not support the new single-card multi-display hardware, and do not make use of Internet resources, do not meet the request of architecture design of software as a service.This paper has proposed a new software architecture, which improves current calibration software kit, is device-centric organization projector display system. This architecture can support the single-card, multi-screen display device. Furthermore, we design and develop the client security authenticate engine to achieve and enhance the whole system run-time security. Global canvas is the whole space for geometry correction process, which is easy for user to design the display wall layout. In the global canvas, the projector mesh can be restructured through mesh deformation technology. In the color correction process, based on the relationship between the global canvas and the whole texture space positions, each vertex texture coordinates can be calculated and the color of blending region can be corrected by the Bezier spline curve technology on the edge of the integration. The real-time color adjustments make to ensure multi-projector instrument edge region natural transition.According Internet software design principles of software as a service, we propose a set of Internet-based multi-projector display system software architecture. This architecture divides system into reasonable components based on traditional local area build system, which forms global canvas layout presentation layer, correction algorithm layer (color correction and geometric correction), correction command transfer layer and parameter storage access layer. The calibration toolkit connects to the service platform for online user authentication, correction result online storage and online project process management. The toolkit in display node shows calibration results through image rendering, by receiving the controller correction command. According to the command, the display node updates multi-projector display wall the in real time by modifying the vertex buffer, texture mapping and light map in graphics rendering pipeline.The system architecture, proposed in this paper, has been successfully implemented in conference room of software school in Zhang Jiang campus of Fudan University. Experimental results show that the global canvas and interactive editing technology can help non-professional users to complete the geometry and color correction work of multi-projector display wall in a short time. The technology can help to implement the special-shaped layout of projectors, as a result the whole display wall screen achieves a good visual effect.