Reduced homography for recovery of pose parameters of an optical apparatus producing image data with structural uncertainty

• US 8,970,709 B2
• Filed: 03/13/2013
• Issued: 03/03/2015
• Est. Priority Date: 03/13/2013
• Status: Active Grant

• Current Assignee: Electronic Scripting Products, Inc.
• Original Assignee: Electronic Scripting Products, Inc.
• Inventors: Gonzalez-Banos, Hector H., Alboszta, Marek, Mandella, Michael J.
• Primary Examiner(s): Perungavoor, Sath V
• Assistant Examiner(s): Brown, Jr., Howard D
• Application Number:
  US13/802,686
• Publication Number:
  US 20130194418A1
• Time in Patent Office: 720 Days
• Field of Search: 348/169
• US Class Current: 348/169
• CPC Class Codes: G01C 11/02 Picture taking arrangements specially adapted for photogrammetry or photographic surveying, e.g. controlling overlapping of pictures
• CPC Class Codes: G06T 2207/10028 Range image; Depth image; 3D point clouds
• CPC Class Codes: G06T 2207/30244 Camera pose
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51
• CPC Class Codes: G06T 7/73 using feature-based methods
• CPC Class Codes: H04N 23/80 Camera processing pipelines; Components thereof

Abstract

A reduced homography H for an optical apparatus to recover pose parameters from imaged space points P_i using an optical sensor. The electromagnetic radiation from the space points P_i is recorded on the optical sensor at measured image coordinates. A structural uncertainty introduced in the measured image points is determined and a reduced representation of the measured image points is selected based on the type of structural uncertainty. The reduced representation includes rays {circumflex over (r)}_i defined in homogeneous coordinates and contained in a projective plane of the optical apparatus. At least one pose parameter of the optical apparatus is then estimated by applying the reduced homography H and by applying a condition on the motion of the optical apparatus, the condition being consonant with the reduced representation employed in the reduced homography H.

Claims

1. A method for recovering pose parameters of an optical apparatus that images space points P_i onto an optical sensor, said method comprising the steps of:

a) recording electromagnetic radiation from said space points P_i on said optical sensor at measured image coordinates {circumflex over (x)}_i,ŷ

_i of measured image points {circumflex over (p)}_i=({circumflex over (x)}_i,ŷ

_i);

b) determining a structural uncertainty in said measured image points {circumflex over (p)}_i=({circumflex over (x)}_i,ŷ

_i);

c) selecting a reduced representation of said measured image points {circumflex over (p)}_i=({circumflex over (x)}_i,ŷ

_i) by rays {circumflex over (r)}_i defined in homogeneous coordinates and contained in a projective plane of said optical apparatus based on said structural uncertainty; and

d) estimating at least one of said pose parameters with respect to a canonical pose by a reduced homography H using said rays {circumflex over (r)}_i.

2. The method of claim 1, wherein said structural uncertainty is due to said optical apparatus.

3. The method of claim 1, further comprising the step of setting a predetermined condition on the motion of said optical apparatus, said predetermined condition being consonant with said reduced representation.

4. The method of claim 3, wherein said predetermined condition is enforced by a mechanism constraining the motion of said optical apparatus.

5. The method of claim 3, wherein said predetermined condition comprises substantially bounding the motion of said optical apparatus to a reference plane at an offset distance d from a viewpoint O of said optical apparatus.

6. The method of claim 3, wherein said predetermined condition is reset based on said at least one of said pose parameters.

7. The method of claim 6, wherein said at least one of said pose parameters is recovered independent of said estimating step.

8. The method of claim 7, wherein said at least one of said pose parameters is recovered by an auxiliary measurement.

9. The method of claim 8, wherein said auxiliary measurement is selected from the group consisting of an optical measurement, an inertial measurement, an acoustic measurement and an RF measurement.

10. The method of claim 9, wherein said optical measurement is performed with said optical apparatus and is further selected from the group consisting of depth-from-defocus and time-of-flight.

11. The method of claim 1, wherein said structural uncertainty is substantially radial.

12. The method of claim 11, wherein said optical sensor retains only azimuthal information a about said measured image points {circumflex over (p)}_i=({circumflex over (x)}_i,ŷ

_i) while setting the radial information r to a constant rc, thereby obtaining image points {circumflex over (p)}_i=(rc,â

_i).

13. The method of claim 1, wherein said structural uncertainty is substantially linear.

14. An optical apparatus for recovering pose parameters of said optical apparatus from images of space points P_i, said optical apparatus comprising:

a) an optical sensor for recording electromagnetic radiation from said space points P_i on said optical sensor at measured image coordinates {circumflex over (x)}_i,ŷ

_i of measured image points {circumflex over (p)}_i=({circumflex over (x)}_i,ŷ

_i);

b) a processor for determining a structural uncertainty in said measured image points {circumflex over (p)}_i=({circumflex over (x)}_i,ŷ

_i) and for selecting a reduced representation of said measured image points {circumflex over (p)}_i=({circumflex over (x)}_i,ŷ

_i) by rays {circumflex over (r)}_i defined in homogeneous coordinates and contained in a projective plane of said optical apparatus based on said structural uncertainty; and

c) an estimation module for estimating at least one of said pose parameters with respect to a canonical pose by a reduced homography H using said rays {circumflex over (r)}_i.

15. The optical apparatus of claim 14, wherein said structural uncertainty is due to said optical apparatus.

16. The optical apparatus of claim 14, wherein said processor sets a predetermined condition on the motion of said optical apparatus, said predetermined condition being consonant with said reduced representation.

17. The optical apparatus of claim 16, further comprising a mechanism for constraining the motion of said optical apparatus to enforce said predetermined condition.

18. The optical apparatus of claim 14, further comprising an auxiliary measurement apparatus for recovering at least one of said pose parameters independent of said estimation module.

19. The optical apparatus of claim 18, wherein said auxiliary measurement apparatus is selected from the group consisting of said optical sensor, an inertial unit, an acoustic unit, an RF measuring unit, a time-of-flight measuring unit.

20. The optical apparatus of claim 14, wherein said structural uncertainty is substantially radial and said optical sensor is configured to retain only azimuthal information a about said measured image points {circumflex over (p)}_i=({circumflex over (x)}_i,ŷ

_i) while setting the radial information r to a constant rc, thereby obtaining image points {circumflex over (p)}_i=(rc,â

_i).

21. The optical apparatus of claim 20, wherein said optical sensor is a one-dimensional position sensing device capturing only azimuthal information a.

22. The optical apparatus of claim 14, wherein said structural uncertainty is substantially linear and said optical sensor is a linear photo sensor.

23. The optical apparatus of claim 22, wherein said linear photo sensor is a linear position sensing device.

24. The optical apparatus of claim 14, wherein said optical apparatus is selected from the group consisting of CMOS camera, position sensing device, CCD camera and PIN photodiode camera.

25. The optical apparatus of claim 14, wherein said space points P_i are point sources of said electromagnetic radiation.

26. The method of claim 25, wherein said point sources comprise optical beacons selected from the group consisting of LEDs, IR LEDs, pixels of a display screen.