RatCAVE: calibration of a projection virtual reality system

Abstract

We have created a suite of automated tools to calibrate and configure a projection virtual reality system. Test subjects (rats) explore an interactive computer-graphics environment presented on a large curved screen using multiple projectors. The locations and characteristics of the projectors can vary and the shape of the screen may be complex. We place several cameras around the workspace for redundant coverage. We locate each projector's hotspot as seen by each camera, and produce a brightness profile which tells the projector how much to dim each pixel of its output to achieve uniform output. We reconstruct the 3D geometry of the screen and the location of each projector using shape-from-motion and structured-light multi-camera computer vision techniques. We determine which projected pixel corresponds to a given view direction for the rat. From these, we create a warping profile for each projector, which tells it how to pre-distort its output image to appear undistorted to the rat's viewpoint. We apply both pre-distortion and hotspot correction before displaying to the screen.