Scalable self-calibrating display technology for seamless large-scale displays

We present techniques for combining high-performance computing with feedback to enable the correction of imperfections in the alignment, optical system, and fabrication of very high-resolution display devices. The key idea relies on the measurement of relative alignment, rotation, optical distortion, and intensity gradients of an aggregated set of low-cost image display devices using a precision low cost reference. Use of the reference allows the construction of a locally correct map relating the coordinate system of the aggregate display to the coordinate systems of the individual projectors composing the display. This idea provides a new technology for linearly scalable, bright, seamless, high-resolution large-scale self-calibrating displays (seamless video walls). Such a large-scale display was constructed using the techniques described in this dissertation. Low-cost computation coupled with feedback is used to provide the precision necessary to create these displays. Digital photogrammetry and digital image warping techniques are used to make a single seamless image appear across the aggregated projection displays. The following techniques are used to improve the display quality: (1) Anti-alias filtering to improve the display of high frequency in images; (2) Limiting the range of displayed intensities to ones that can be displayed uniformly across all the projectors; and (3) Applying intensity smoothing functions to the regions of the image that are projected in the overlapping region. These functions smoothly and gradually transition the projection among the projectors. The resultant systems demonstrate the viability of the approach by succeeding where other approaches have failed; it makes huge seamless video walls a reality. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)