Fixed-Center Pan-Tilt Projector and Its Calibration Methods Ikuhisa Mitsugami Norimichi Ukita Ma satsugu Kidode Graduate School of Information Science Nara Institute of Science and Technology Objectives: Drawing graphics on the planar surfaces in t he environment by projectors. Precisely at where we would like it be. Without any distortions. Enable to move it freely on the planes. Even when it moves across a boundary of two planes, it should lie in the similar way to a paper poster folded a long the planes. How to accomplish it? Steerable (enable to pan and tilt) mechanism. “Fixed-center pan-tilt (FC-PT) projecto r.” Multiple FC-PT projectors can be used for larger sp ace. wall R relation image plane P 1 projector board light projector board light pan tilt projector screen 2 projec ted point screen 1 3D translation plane R initial orientation tangent plane Q (X, Y) another orienta tion initial center direction center direction at the orientation (u, v) u v ) tan , (tan t p ) , ( t p ) , ( t p 1 tilt axis pan axis Introduction Normal (fixed) projector Normal pan-tilt projector FC-PT projector. Implementation of FC-PT Projector Projection to One Plane Projection to Multiple Planes Experimental Results Rough estimation of projection center Precise fixing Future Works Advantages of FC-PT Projector Automatic set-up of FC-PT projectors. Cooperation with cameras. Cooperation of multiple FC-PT projectors. For display of larger graphics than the capacity of one project Correction of misalignment among the graphics of the projectors Specification Projector: PLUS VISION V3-131 Projection System: DLP Resolution: 1024*767 (XGA) Brightness: 1000 lm Contrast Ratio: 2000:1 Steerable stage Orientation accuracy: 0.002 deg Rotating speed: 10 deg/s (X, Y) (x, y) image plane P 1 wall R relation ) , ( t p image plane P 2 image plane P 1 wall R projector relation (X, Y) (x, y) wall R projector ) , ( t p image plane P 2 image plane P 1 relation corresponding area of P 1 wall R tangent plane Q FC-PT projector corresponding area of P 2 relation H wall R tangent plane Q FC-PT projector X Y Introduction of “tangent plane” Q. Image planes of all orientations can be projected on Q. As Q does not move, the relation between Q and R is fixed. Their relation H can be determined by 4 pairs of coordinates on Q and R. (horizontal view) (vertical view) tangent plane Q plane R 0 image plane inversely distorted graphic graphic to draw ' QP H ) ' , ' ( t p ) , ( ) ( ) ( gra k gra k v u ) , ( ) ( ) ( pro j pro j v u ' P ) , ( ) ( ) ( gra k gra k Y X FC-PT projector R c R m graphic G m corresponding area of R m T m : intersecti on of G m and R m center direct ion tangent plane Q S m : projecti on of T m R’ c By connectivities of multiple planes in the environment and 2D coordinate of every plane, transformations parameters between 2D coordinates of every 2 are calculated. To display graphics on planes, all we have to do are: locate the FC-PT projector anywhere we like, measure the 2D metric size of the plane, and direct the projector to 4 corners of the plane and record them. FC-PT projector can provide: 1) Easy set-up, 2) Precise display, 3) Real-time process. G c is calculated from G m by the transformation between R m and R c R c R m S m graphic G c FC-PT projector R’ m T c : intersecti on of G c and R c tangent plane Q corresponding area of R c S c : projecti on of T c center direct ion Input image to projector Projection result on the walls