Camera tracking system

• US 5,889,550 A
• Filed: 06/10/1996
• Issued: 03/30/1999
• Est. Priority Date: 06/10/1996
• Status: Expired due to Term

• Current Assignee: AOA Xinetics (Northrop Grumman Corporation)
• Original Assignee: AOA Xinetics (Northrop Grumman Corporation)
• Inventors: Reynolds, Mark C.
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US08/661,201
• Time in Patent Office: 1,023 Days
• Field of Search: 348/42, 348/94, 348/95, 348/139, 348/169, 348/722, 348/135, 348/143, 345/158, 364/559, 901/47
• US Class Current: 348/139
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: H04N 5/222 Studio circuitry; Studio devices; Studio equipment cameras or camera modules comprising electronic image sensors, or control thereof H04N23/00
• CPC Class Codes: H04N 5/2224 related to virtual studio applications

Abstract

A camera tracking system determines the three dimensional (3D) location and orientation of the film plane of a camera providing live recording of a subject, thereby defining a 3D coordinate system of the live action scene into which animated objects or characters may be automatically mapped with proper scale and 3D visual object by a computer animation system.

Claims

1. Apparatus for providing, to user animation equipment, the three dimensional coordinate data identifying the location and orientation of the image plane of a recording camera which is visually recording subjects on a three dimensional film stage, comprising:

a target assembly, having a plurality of light reflective markers disposed in a geometric pattern thereon, said pattern including a target plane, said target assembly being adapted for mounting to the recording camera in a manner such as to position said target plane parallel to the film plane of the recording camera;

a motion capture system, having a plurality of viewer cameras and associated video processors, for recording the spatial location and orientation of said target assembly markers in each of a plurality of successive sample intervals with each of said plurality of viewer cameras; and

for providing at an output thereof said recorded location and orientation as a two dimensional data set from each of said plurality of associated video processor in each said sample interval; and

signal processing means, responsive to each said two dimensional data set from each said associated video processor in each said sample interval, for reviewing at least two of said two dimensional data sets in each said sample interval and for reconstructing therefrom a result set of three dimensional coordinate data for each said sample interval, each said three dimensional data set being indicative of the location and orientation of the film plane of the recording camera in its related sample interval.

2. The apparatus of claim 1, wherein said plurality of viewer cameras are placed in position around the recording camera, each at a different sightline to the target assembly.

3. The apparatus of claim 1, wherein said target assembly comprises:

a support structure, having a different one of a plurality of structural members thereof arrayed in each of three substantially orthogonal geometric planes, said support structure further having a mounting member adapted to mount said structure to the recording camera; and

a plurality of light reflective markers arrayed in a known pattern among said plurality of structural members, at least one each of said plurality of markers being located in a different one of said three orthogonal planes, said plurality of markers being responsive to the pulsed light from the motion capture system viewer cameras to reflect a known three dimensional pattern of light.

4. The target assembly of claim 3, wherein said plurality of structural members comprise a light absorbent outer surface.

5. The target assembly of claim 3, wherein said light reflective markers are substantially spherical in shape.

6. The target assembly of claim 3, wherein said plurality of light reflective markers comprises at least three said markers.

7. The target assembly of claim 3, wherein said plurality of light reflective markers comprises at least five said markers.

8. The target assembly of claim 3, wherein said plurality of markers each have an exterior surface of SCOTCHLITE™

8710 reflective transfer film.

9. The apparatus of claim 7, wherein said plurality of viewer cameras are positioned around the recording camera, at different sightlines to said target assembly.

10. The apparatus of claim 9, wherein each of said plurality of viewer cameras record 2D projections of the location and orientation of said target assembly in successive sample intervals, beginning from a calibrated reference position of the camera, the sample intervals having a periodicity at least equal to the recording intervals of the recording camera so as to associate each recording interval with at least one set of 2D projection data, the calibrated reference position of the camera being established with a calibration procedure performed prior to the recording session to provide a baseline position from which all subsequent camera motion is measured in relation to.

11. The apparatus of claim 1, wherein said signal processing means provides each said three dimensional data set using a direct linear transform mathematical process.

12. The apparatus of claim 1, wherein said signal processing means provides each said three dimensional data set using the collinearity equations mathematical process.

13. A target assembly, for use in a system of the type which uses a motion capture system, having a plurality of pulsed light viewer cameras for recording the spatial location and orientation of the image plane of a recording camera recording subjects on a three dimensional film stage, comprising:

a support structure, having a different one of a plurality of structural members thereof arrayed in each of three substantially orthogonal geometric planes, said support structure further having a mounting member adapted to mount said structure to the recording camera; and

a plurality of light reflective markers arrayed in a known pattern among said plurality of structural members, at least one each of said plurality of markers being located in a different one of said three orthogonal planes, said plurality of markers being responsive to the pulsed light from the motion capture system viewer cameras to reflect a known three dimensional pattern of light.

14. The target assembly of claim 13, wherein said plurality of structural members comprise a light absorbent outer surface.

15. The target assembly of claim 13, wherein said light reflective markers are substantially spherical in shape.

16. The target assembly of claim 13, wherein said plurality of light reflective markers comprises at least three said markers.

17. The target assembly of claim 13, wherein said plurality of light reflective markers comprises at least five said markers.

18. The target assembly of claim 13, wherein said plurality of markers each have an exterior surface of SCOTCHLITE™

8710 reflective transfer film.