Fixed-Center Pan-Tilt Projector and Its Calibration Methods

1. image plane inversely distorted graphic graphic to draw plane R0 tangent plane Q (X, Y) Tc: intersection of GcandRc (x, y) R’m R’c image plane P1 image plane P1 Tm: intersection of GmandRm graphic Gc graphic Gm relation relation wall R wall R Rm Rc Sm Rm Rc corresponding area of Rc image plane P1 image plane P1 corresponding area of Rm (X, Y) (x, y) tangent plane Q image plane P2 image plane P2 centerdirection tangent plane Q Sc: projection of Tc projector projector relation Sm: projection of Tm relation centerdirection wall R wall R FC-PT projector X FC-PT projector corresponding area of P1 center direction at the orientation Y wall R 1 tangent plane Q (X, Y) initial center direction another orientation corresponding area of P2 relation H (u, v) FC-PT projector FC-PT projector tangent plane Q tangent plane Q wall R initial orientation tilt axis u plane R pan axis v board board projector pan projector 3D translation light light projector screen 1 tilt projected point screen 2 Fixed-Center Pan-Tilt Projector and Its Calibration Methods Ikuhisa Mitsugami Norimichi Ukita Masatsugu KidodeGraduate School of Information ScienceNara Institute of Science and Technology Introduction Projection to One Plane • Objectives: Drawing graphics on the planar surfaces in the 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 along the planes. • How to accomplish it? • Steerable (enable to pan and tilt) mechanism.  “Fixed-center pan-tilt (FC-PT) projector.” • Multiple FC-PT projectors can be used for larger space. Projection to Multiple Planes By • connectivities of multiple planes in the environment and • 2D coordinate of every plane, transformations parameters between 2D coordinates of every 2 planes are calculated. Advantages of FC-PT Projector • Normal (fixed) projector Gc is calculated from Gmby the transformation between Rm and Rc • Normal pan-tilt projector • FC-PT projector. • 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. Experimental Results • 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 • 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. Input imageto projector Projection resulton the walls Implementation of FC-PT Projector • Precise fixing • Rough estimation of projection center Future Works • 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 projector. • Correction of misalignment among the graphics of the projectors. (horizontal view) (vertical view)