Method and apparatus for calibrating geometrically an optical computer input system

• US 5,933,132 A
• Filed: 05/15/1996
• Issued: 08/03/1999
• Est. Priority Date: 11/07/1989
• Status: Expired due to Fees

• Current Assignee: Straight Signals LLC (Intellectual Ventures LLC)
• Original Assignee: Proxima Corporation (Ask ASA)
• Inventors: Marshall, Roger N., Hauck, Lane T.
• Primary Examiner(s): WU, XIAO MIN
• Application Number:
  US08/648,659
• Time in Patent Office: 1,175 Days
• Field of Search: 345/7, 345/8, 345/158, 345/180, 345/182, 345/183, 345/157, 348/187, 348/189, 348/190, 348/744, 348/745, 348/746, 348/747, 348/806, 395/141, 395/441, 382/293, 382/294
• US Class Current: 345/158
• CPC Class Codes: G06F 3/0425 using a single imaging device like a video camera for tracking the absolute position of a single or a plurality of objects with respect to an imaged reference surface, e.g. video camera imaging a display or a projection screen, a table or a wall surface, on which a computer generated image is displayed or projected tracking a projected light spot to determine a position on a display surface G06F3/0386
• 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

Abstract

A method and apparatus geometrically makes correction in an optical computer input system.

Claims

1. A coordinate correction apparatus comprising:

image detection means for perceiving visually a displayed generally rectangularly shaped projected image having keystone distortion;

hand held auxiliary light means for successively illuminating the corners of the distorted image with spots of high intensity auxiliary control light for facilitating defining the geometric form of the keystone distortion in the projected image;

said image detection means responsive to said spots of high intensity light only during a calibration mode for generating a signal indicative of the location of the high intensity spots;

signal processing means responsive to said signal during said calibration mode for determining the geometric center of the geometric form of the keystone distortion defined by the intersection coordinate values of a pair of imaginary lines interconnecting the detected spots of high intensity light;

distortion orientation calculating means responsive to the determined geometric center for determining quadrant scaling factors to facilitate determining corrected coordinate values for detected spots of high intensity auxiliary control light during a normal mode of operation;

said signal processing means storing the scaling factors for use during said normal mode of operation to enable said signal processing means to convert subsequently a determined auxiliary light sensing coordinate value relative to another computer generated projected image having substantially the same keystone distortion as said first mentioned projected image;

said signal processing means using said stored scaling factors for converting the determined auxiliary light sensory coordinate values to absolute coordinate values, said absolute coordinate values being indicative of corresponding coordinate value information defining a fixed location within said another computer generated image.

2. An apparatus according to claim 1, further comprising:

means for determining the corner x,y coordinate values for each respective corner of the displayed image; and

means for determining the x,y coordinate values for a defined center within the displayed image area, wherein said image area is bounded by the four respective edges of the displayed image.

3. An apparatus according to claim 2, wherein said means for determining the x,y coordinate value for said defined center includes point slope determining means.

4. An apparatus according to claim 3, wherein said point slope determining means includes algorithm means.

5. An apparatus according to claim 4, wherein said algorithm means includes means for solving an equation:

##EQU20## wherein y_TL is indicative of a determined Y top left coordinate value;

wherein Y_BR is indicative of a determined y bottom right coordinate value;

wherein X_TL is indicative of a determined X top left coordinate value; and

wherein X_BR is indicative of a determined Y bottom right coordinate value.

6. An apparatus according to claim 5, wherein said algorithm means includes means for solving a pair of equations:

##EQU21##

7. An apparatus according to claim 1 further comprising:

means for determining the x,y coordinate locations of each respective corner of the displayed image; and

means for determining a defined center coordinate location for the displayed image.

8. An apparatus according to claim 1, wherein said distortion orientation calculating means includes:

means for calculating an adjusted edge for both X and Y stored determined correction coordinate location values in the quadrant of the determined geometric center; and

means for calculating an absolute x value and an absolute y value.

9. An apparatus according to claim 8, wherein said absolute y value is:

##EQU22##10.

10. An apparatus according to claim 9, wherein said Y_relative is:

space="preserve" listing-type="equation">Y.sub.relative =Y.sub.SPOT -Y.sub.c.

11. An apparatus according to claim 10, wherein said y_spot is indicative of the y coordinate value of the projected x,y coordinate image of light.

12. An apparatus according to claim 8, wherein said absolute x value is ##EQU23##

13. An apparatus according to claim 12, wherein said X_RELATIVE is:

space="preserve" listing-type="equation">X.sub.relative =X.sub.SPOT -X.sub.left edge.

14. An apparatus according to claim 13, wherein said x_SPOT is indicative of the x coordinate image of light.

15. An apparatus according to claim 14, wherein said X left edge is X_TL.

16. An apparatus according to claim 13, wherein said X left edge is X_TL.

17. An apparatus according to claim 1, further comprising:

said image detection means responsive to the projected image in another calibration mode for perceiving visually the distorted image and for generating a video signal indicative of the projected image;

said signal processing means further being responsive to said image detection means for determining image detection coordinate values for the distorted image, said distorted image having four determined corner coordinate values and associated right, left, top and bottom boundaries;

left boundary distortion determination means for calculating whether or not the left boundary is aligned vertically relative to its associated determined corner coordinate values;

right boundary distortion determination means for calculating whether or not the right boundary is aligned vertically relative to its associated determined coordinate values;

top boundary distortion determination means for calculating whether or not the top boundary is aligned horizontally relative to its associated determined corner coordinate values;

bottom boundary distortion determination means for calculating whether or not the bottom boundary is aligned horizontally relative to its associated determined corner coordinate values;

left distortion orientation means responsive to said left boundary distortion determination means for determining whether determined left boundary distortion is rectangular distortion or triangular distortion;

left triangular distortion correction means for calculating a set of corrected image detection coordinate values for the left edge of the distorted image;

left rectangular distortion correction means for calculating another set of corrected image detection coordinate values for the left edge of the distorted image;

absolute correction means responsive to said left triangular distortion correction means and said left rectangular distortion correction means for converting one set of the left edge corrected image detection coordinate values to absolute computer coordinate values;

right distortion orientation means responsive to said right boundary distortion determination means for determining whether determined right boundary distortion is rectangular distortion or triangular distortion;

right triangular distortion correction means for calculating a set of corrected image detection coordinate values for the right edge of the distorted image;

right rectangular distortion correction means for calculating another set of corrected image detection coordinate values for the right edge of the distorted image;

absolute correction means responsive to said right triangular distortion correction means and said right rectangular distortion correction means for converting one set of the right edge corrected image detection coordinate values to absolute computer coordinate values;

top distortion orientation means responsive to said top boundary distortion determination means for determining whether determined top boundary distortion is rectangular distortion or triangular distortion;

top triangular distortion correction means for calculating a set of corrected image detection coordinate values for the top edge of the distorted image;

top rectangular distortion correction means for calculating another set of corrected image detection coordinate values for the top edge of the distorted image;

absolute correction means responsive to said top triangular distortion correction means and said top rectangular distortion correction means for converting one set of the top edge corrected image detection coordinate values to absolute computer coordinate values;

bottom distortion orientation means responsive to said bottom boundary distortion determination means for determining whether determined bottom boundary distortion is rectangular distortion or triangular distortion;

bottom triangular distortion correction means for calculating a set of corrected image detection coordinate values for the bottom edge of the distorted image;

bottom rectangular distortion correction means for calculating another set of corrected image detection coordinate values for the bottom edge of the distorted image;

absolute correction means responsive to said bottom triangular distortion correction means and said bottom rectangular distortion correction means for converting one set of the bottom edge corrected image detection coordinate values to absolute computer coordinate values; and

whereby corrected coordinate values for the right, left, top and bottom boundaries are calculated to substantially eliminate errors in input coordinate information resulting from keystone image distortion in the projected image.

18. An apparatus for substantially eliminating errors in optical input information resulting from image distortion in a projected image, comprising

means for determining image detection coordinate values for any detected substantially flat generally rectangularly shaped projected image having possible edge distortion, said distortion being a distortion caused by a height differential between the position of the projected image on a viewing surface relative to the position of image projection means producing the projected image;

said determined image detection coordinate values including four determined corner coordinate values;

boundary distortion determination means for calculating whether or not any boundary between a pair of adjacent determined corner coordinate values is aligned rectilinearly relative to its associated determined corner coordinate values;

distortion orientation means responsive to said boundary distortion determination means for determining the orientation of the distortion relative to an imaginary rectilinear line forming part of an imaginary rectilinearly shaped image;

distortion correction means for calculating a set of corrected image detection coordinate values to eliminate errors in coordinate information resulting from edge distortion in the projected image; and

absolute correction means responsive to said distortion correction means for converting said set of corrected image detection coordinate values to absolute coordinate values, said absolute coordinate values being indicative of corresponding coordinate value information generated by said image projection means.