Multi-projection Fusion System For Special-shaped Metal Screen

Splicing multiple projected images on a special-shaped screen is a common method to provide a large-scale,high-resolution,and seamless visual experience.multiple projectors construct a seamless image result by overlapping their respective projected images,so that the viewer can enjoy an immersive visual experience.Therefore,XD Cinema,Flying Cinema,Spherical Screen Cinema,etc.based on curved projection screens have been increasingly used in various fields,including theme parks,digital museums,education and training,scientific popularization,and so on.With the gradual increase of user needs,the material,area and arrangement of the curtain in the multi-projection system are also gradually changing.Facing the problems of gradually increasing the gain coefficient of the projection screen and gradually increasing the area of the screen,the traditional multi-projection fusion system often cannot adapt well.The reason is that the traditional fusion system has better adaptability to flat screens or small and medium-sized special-shaped screens,but for the currently popular special-shaped metal screens,there are some problems that need to be solved.Therefore,the development of a multi-projection fusion system for a special-shaped projection screen has a good market demand.The main challenges faced by such systems are:firstly,how to effectively calibrate the geometric deformation of the image caused by projection onto the curved surface;secondly,how to effectively integrate the global brightness change caused by the high screen gain coefficient and the dramatic brightness change of the overlapping area,including the consistency of the brightness seen under different viewpoints.To this end,this paper has developed a multi-projection mosaic fusion system for metal curved screens.First,requirements analysis,outline design and detailed design were carried out.In the requirements analysis section,the needs of the multi-projection system are analyzed,the system overview is described,the system requirements are classified,and then the relevant key technologies and hardware environment are introduced.In the outline design section,the process architecture and functional architecture of the system are described.In the detailed design section,detailed schemes and detailed designs are made for each subsystem and module in the system functional architecture.Finally,based on the above analysis and design,each part of the system is implemented,and the completed system is tested to verify the effectiveness of the system's implementation scheme.In the system development process,we mainly tackled the following difficult issues:1)The system needs to use the camera to capture the projected image on the curtain for camera calibration,geometric splicing and brightness fusion.Aiming at the problem that the field of view of ordinary camera lenses is difficult to cover a large screen,this article uses a dual-camera fisheye lens to minimize the impact of space constraints and cover a large field of view.At the same time,an effective solution is proposed for the distortion problem and incompatibility of stereo calibration in the fisheye lens itself.2)Aiming at the problem of geometric correction and image mosaic of multi-projection images under special-shaped screens,a quadratic surface fitting based on the Taubin method was used to perform continuous and complete 3D restoration of the special-shaped screens.Based on this,a one-to-one mapping relationship from the physical pixels of the projector to the pixels of the actual projected image is achieved,thereby achieving a good image mosaic result.3)For the special-shaped metal curtain,the high gain coefficient of the curtain will cause the brightness observed by the user in different positions to be inconsistent.In addition to this,the projection brightness of the overlapping area has also been significantly improved.In view of this problem,the brightness of the RGB channels is corrected separately to concentrate the brightness in a relatively small brightness area as much as possible to achieve natural mosaic of the projection area and a more comfortable and natural user experience.