For Multi-projector Display Surface Correction Technology

With the rapid development of projection technology, building large-format multi-projector display systems has become a great concern in the research area. Multi-projector display technology has been considered to be an important means 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 constructing multi-projector display system, we need first to calibrate the projector's output image to achieve seamless image on the screen. For the calibration work, we can classify it to geometry calibration and photometric calibration. Currently, most research group focus on how to calibrate the multi-projector display precisely on planar screen or simple cylinder screen. However, there is less method on how to solve the calibration on large complex screen.We summarize recent popular methods on the geometry calibration and photometric calibration. Then we make our efforts to give our solutions on how to do the calibration work on complex irregular screen. We first give a method that is suitable for relatively small complex screen. This method is based on camera. We use projectors as the light source to project the global mesh. By proper mesh deformation, we can get a rigid global mesh on the screen. We then give each projector a display mesh. We use camera to capture the display mesh and global mesh, then the texture coordinates of the vertices can be evaluated. We also employ Bezier spline curve to interactive edit the edge blending curve. Comparing with the traditional method that pasting some features onto the screen, this method is more flexible and practicable.For large complex screen, the method that based on camera is a bit limited. We improve the original method and make it suitable for large complex screen. We use Full Space Canvas technique and interactive editing method properly solved the large image splitting and multi-projector calibration problems. Then, we use interactive mask editing method to mask the image that is outside of the screen. We implemented our system and deployed the system in the World Exposition Museum of Shanghai 2010 Expo.The result shows that our Full Space Canvas technique and interactive editing method can properly solve the calibration work without much loss in the accuracy. The calibration work can be finished quickly and precisely. Our system gets a very brilliant visual experience.