Camera calibration

Patent metadata

Field	Value
Publication number	US-9491452-B2
Application number	US-201414498801-A
Country	US
Kind code	B2
Filing date	Sep 26, 2014
Priority date	Sep 5, 2014
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

Abstract

Techniques for image calibration are described herein. The techniques may include detecting features on a set of images, describing features on the set of images, determining a match between features of the image sets, determining a shift on the matched features based on camera positions associated with the matched features, determining a first homography between the camera positions and the determined shift, and determining a second homography based on a re-projection of three-dimensional features back to the cameras.

First claim

What is claimed is:

1. A system for image calibration, comprising:
a processing device; and
modules to be implemented by the processing device, the modules comprising:
a feature module to:
detect features on a set of images;
describe features on the set of images;
determine a match between features of the image sets; and

a homography module to:
determine a shift on the matched features based on camera positions;
determine a first homography between the camera positions and the determined shift;
reconstruct the detected features in three-dimensions; and
determine a second homography based on a re-projection of the three-dimensional features back to a plurality of cameras.

2. The system of claim 1 , further comprising a rectifier module configured to rectify the set of images with an original homography from a manufacture calibration, wherein the rectification is performed before the feature detection of the feature module.

3. The system of claim 1 , wherein the images of an image set comprise images each captured at a different camera comprising at least three cameras.

4. The system of claim 1 , wherein the images of the image set comprise images captured at a single camera disposed at different positions.

5. The system of claim 1 , further comprising an outlier module configured to:
discard outliers based on feature match angle above a predetermined threshold; and
discard outliers based on a feature match size above a predetermined threshold.

6. The system of claim 5 , wherein the outlier module is further configured to discard outliers where a feature match occurs on less than three cameras.

7. The system of claim 5 , wherein the outlier module is further configured to determine a scale of the shift indicating the difference of feature coordinates between image sets divided by a displacement associated with each image captured.

8. The system of claim 1 , wherein the second homography is homography between original feature coordinates from manufacturer calibration and feature coordinates based on the re-projection of the three dimension reconstruction to one or more cameras.

9. The system of claim 8 , wherein the three dimension reconstruction estimates scene depth.

10. The system of claim 1 , wherein the modules are operable ad hoc as images are captured.

11. A method for image calibration, comprising:
detecting, with a processing device, features on a set of images;
describing features on the set of images;
determining a match between features of the image sets;
determining a shift on the matched features based on camera positions associated with the matched features;
determining a first homography between the camera positions and the determined shift; reconstructing the detected features in three-dimensions; and
determining a second homography based on a re-projection of the three-dimensional features back to a plurality of cameras.

12. The method of claim 11 , further comprising rectifying the set of images with an original homography from a manufacture calibration, wherein the rectification is performed before the feature detection of a feature module.

13. The method of claim 11 , wherein the images of an image set comprise images each captured at a different camera comprising at least three cameras.

14. The method of claim 11 , wherein the images of the image set comprise images captured at a single camera disposed at different positions.

15. The method of claim 11 , further comprising:
discarding outliers based on feature match angle above a predetermined threshold; and
discarding outliers based on a feature match size above a predetermined threshold.

16. The method of claim 11 , further comprising discarding outliers where a feature match occurs on less than three cameras.

17. The method of claim 11 , further comprising determining a scale of the shift indicating the difference of feature coordinates between image sets divided by a displacement associated with each image captured.

18. The method of claim 11 , wherein the second homography is homography between original feature coordinates from manufacturer calibration and feature coordinates based on the re-projection of the three dimension reconstruction to one or more cameras.

19. The method of claim 18 , wherein the three dimension reconstruction estimates scene depth.

20. The method of claim 11 , wherein the method is operable ad hoc as images are captured.

21. A non-transitory, computer readable medium including code, when executed, to cause a processing device to:
detect features on a set of images;
describe features on the set of images;
determine a match between features of the image sets;
determine a shift on the matched features based on camera positions associated with the matched features;
determine a first homography between the camera positions and the determined shift;
reconstruct the detected features in three-dimensions; and
determine a second homography based on a re-projection of the three-dimensional features back to a plurality of cameras.

22. The computer readable medium of claim 21 , further comprising code, when executed, to cause the processing device to rectify the set of images with an original homography from a manufacture calibration, wherein the rectification is performed before the feature detection of a feature module.

23. The computer readable medium of claim 21 , wherein the images of an image set comprise images each captured at a different camera comprising at least three cameras.

24. The computer readable medium of claim 21 , wherein the images of the image set comprise images captured at a single camera disposed at different positions.

25. The computer readable medium of claim 21 , further comprising code, when executed, to cause the processing device to:
discard outliers based on feature match angle above a predetermined threshold; and
discard outliers based on a feature match size above a predetermined threshold.

Assignees

• Intel Corp

Inventors

• Meloun Martin
• Middleton Daniel C

Classifications

• H04N23/90

  Arrangement of cameras or camera modules, e.g. multiple cameras in TV studios or sports stadiums · CPC title

• H04N23/45

  for generating image signals from two or more image sensors being of different type or operating in different modes, e.g. with a CMOS sensor for moving images in combination with a charge-coupled device [CCD] for still images · CPC title

• G06F18/22

  Matching criteria, e.g. proximity measures · CPC title

• G06F18/24

  Classification techniques · CPC title

• G06V10/7515

  Shifting the patterns to accommodate for positional errors · CPC title