Study On Low-Cost Multi-Projector Mosaic

Large format high-resolution display systems are becoming increasingly important for wide use in scientific visualization, industrial design, virtual manufacturing, military simulation and entertainment applications. Common systems, such as large display wall or high quality projector are extremely expensive. A popular approach to building such displays is the projector array, where several projectors are tiled to create a seamless, high-resolution display.Research in building a large, high-resolution display system has become increasing popular. Tiled projector arrays require precise calibration in order to appear seamless. There are three main aspects of projector mosaic: geometric calibration, color calibration and intensity blending. Geometric calibration is needed to remove the discontinuity caused by mis-aligned projectors in the overlapped regions; Due to photometric imbalance within and among the projectors, color calibration is needed to achieve uniform effectiveness of such a display; In order to seamlessly merge the images without any obvious overlapped region, intensity blending is needed.Famous large, high-resolution display systems, such as Princeton Scalable Display Wall, require aligning projectors precisely and take up large construction room. The installation and operation of such systems is extremely expensive.Raskar et al proposed to create a low-cost but easy-to-use multi-projectors mosaic system by exploiting computer vision. The cost of the system is simply the cost of the projector in addition to the inexpensive camera and software. But color calibration and photometric correction were neglected, thus the system can be improved greatly. Based on these researches, the paper proposes a approach to constructing a low-cost, large display by integrating multi-projectors and includes thefollowing work:(1) By utilizing an attached camera to computer relative pose between camera and projectors, automatic geometric calibration of projectors is be obtained. To obtain a homography, the projectors display calibration checkerboard on a blank planar screen and checkerboard points on the projector images and camera images are extracted by exploiting computer vision techniques.(2) The paper proposes a color calibration approach based on nonlinear optimization method. The camera captures the color checkerboard which are be projected by the projectors and the transformation relationship between projector color value and standard color value can be computed by nonlinear optimization method.(3) The linear intensity blending function is improved.(4) The low-cost, large display system by integrating multi-projectors has been designed and developed. Most key modules of the software system have been implemented.The cost of the large display system by integrating multi-projectors is simply the cost of projector and PC in addition to an inexpensive camera and software. The system is smart and flexible, can be achieved at a college, marketplace even office so that increasing people can enjoy the charm of a high resolution, large format display in the fields of interaction with information and digital entertainment.