National Science Foundation
C. Jaynes, S. Webb, M. Steele, M. Brown, and B. Seales, Dynamic Shadow Removal from Front-Projection Displays , IEEE Visualization, San Diego, 2001.
In the case of a front-projected, loosely configured display, users may inadvertently cast shadows on the display surface. The Metaverse Portal can automatically detect the presence of a shadow and, if a second projector overlaps the same region, it can be instructed to remove the shadow in real-time. The shadow removal system has been demonstrated on a projected display in the laboratory and is capable of removing shadows at approximately five frames per second.
Our approach is to generate a synthetic view of the display that can be compared to the image captured by a camera at any given instant. A monitoring camera must be able to accurately predict the appearance of the display at any given moment. Display appearance is governed by the relative position of the camera to the display as well as a color transfer function that maps pixel values in a framebuffer to expected value in the camera. Differences in the predicted versus the captured image may correspond to a shadow event. Detected shadowed regions are projected to unoccluded projectors where appropriate pixel values are increased. The unoccluded projectors then fill in the shadow event at frame-rate speeds.