Scaling up multiprojector immersive displays: the LightTwist project

Summary form only given. As video projectors are becoming less expensive, we see more and more use of multiple projectors to create a single coherent image, the so-called multi- projectors displays. They provide higher resolution, larger screen size as well as more flexible screen shape. However, they must be carefully aligned and calibrated and the media, video as well as 3D, becomes harder to manage and display. By using a camera, it is possible to automatically align geometrically and photometrically the projectors using structured light. The LightTwist project aims at providing this alignment as well as media spatialization and synchronization and projection, in a real context, i.-e. outside the controlled environment of the research lab. In an attempt to truly free the artists from the limitations inherent to single projectors, this project works with common hardware and imposes very few constraints on the projector-screen geometry while simplifying the use of a large number of projectors. For cylindrical or spherical immersion the number of projectors tends to increase, thereby increasing the ratio of projected pixels to cameras pixels. This makes the accurate inversion of the camera-projector mapping a real challenge, especially in regions of overlap between the projectors. This "pixel ratio problem", as well as other issues such as camera calibration, real-time performance, and synchronization with sound, have been tested in this project and will be presented as well as examples of real installations.