Projector-camera system with laser pointers

• US 7,137,707 B2
• Filed: 07/01/2004
• Issued: 11/21/2006
• Est. Priority Date: 07/01/2004
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Inventors: Raskar, Ramesh, van Baar, Jeroen, Beardsley, Paul A.
• Primary Examiner(s): Perkey, W. B.
• Assistant Examiner(s): SEVER, ANDREW T
• Application Number:
  US10/883,224
• Publication Number:
  US 20060001839A1
• Time in Patent Office: 873 Days
• Field of Search: 353/60, 353/70, 353/42, 353/121, 353/28, 353/7, 348745-747, 348135-142
• US Class Current: 353/69
• CPC Class Codes: G03B 17/54 with projector
• CPC Class Codes: G03B 21/26 Projecting separately subsidiary matter simultaneously with main image
• CPC Class Codes: H04N 5/74 Projection arrangements for image reproduction, e.g. using eidophor
• CPC Class Codes: H04N 9/3185 Geometric adjustment, e.g. keystone or convergence optical or mechanical adjustment of convergence H04N9/317; using scanning means H04N3/22; optical or mechanical adjustments of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/14
• CPC Class Codes: H04N 9/3194 including sensor feedback

Abstract

A rigidly-coupled projector-camera system is augmented with laser pointers. The projector-camera system and lasers can be used to determine homography between the projector and a display surface, so that a projection of any desired geometry can be made on the display surface.

Claims

1. A method for determining a projector pixel that is related by pinhole projection to a laser point on a display surface, comprising:

projecting a laser point onto a display surface with a laser pointer;

viewing the laser point with a camera in a fixed relationship with respect to the laser pointer and with respect to a projector, in which the laser pointer and the camera are mounted rigidly on the projector;

projecting a set of projector points onto the display surface with the projector;

viewing the set of projector points with the camera;

determining a planar homography between the camera and projector defined by a correspondence between the projector points in a projector image plane and the projector points in a camera image plane;

using the planar homography to transform the laser point from the camera image plane to the projector image plane as transformed laser points;

determining a location of a first line in the camera image plane passing through the set of laser points acquired as a distance varies between the laser pointer and the display surface;

determining a location of a second line in the projector image plane passing through the set of transformed laser points acquired as the distance varies between the laser pointer and the display surface;

determining a line homography between the first line and the second line using the laser points and the corresponding transformed laser points;

viewing a subsequent laser point with the camera, and using the line homography to transform the subsequent laser point to the projector image plane to determine a location of a pixel on the projector image plane related by pinhole projection to the subsequent laser point on the display surface, in which the pixels are set to give a fixed projection on the display surface while the projector is moving.

2. The method of claim 1, in which four or more laser points from four or more laser pointers are viewed by the camera, and the transformed points on the projector image plane are determined by each of four or more line homographies determined for the four or more laser points, and the four or more laser points and corresponding transformed four or more laser points are used to determine a planar homography between the camera and projector.

3. The method of claim 2, in which the camera detects four fixed physical points on the display surface, and uses the planar homography to transform the physical points to the projector image plane, and uses the transformed points to define a coordinate frame on the projector image plane, and sets the value of other pixels on the projector image plane relative to the coordinate frame, so that a projection on the display surface by the projector is in correspondence to the physical points as the pixels are in correspondence with the coordinate frame.