CAMERA CALIBRATION

• US 20160182903A1
• Filed: 12/19/2014
• Published: 06/23/2016
• Est. Priority Date: 12/19/2014
• Status: Active Grant

• Current Assignee: Disney Enterprises Incorporated (The Walt Disney Company)
• Original Assignee: Disney Enterprises Incorporated (The Walt Disney Company)
• Inventors: GRUNDHFER, Anselm
• Granted Patent: US 9,560,345 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06T 2207/30204 Marker
• CPC Class Codes: G06T 2207/30244 Camera pose
• CPC Class Codes: G06T 7/74 involving reference images or patches
• CPC Class Codes: G06T 7/80 Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration
• CPC Class Codes: H04N 17/002 for television cameras

Abstract

Embodiments herein include systems, methods and articles of manufacture for calibrating a camera. In one embodiment, a computing system may be coupled to a calibration apparatus and the camera to programmatically identify the intrinsic properties of the camera. The calibration apparatus includes a plurality of light sources which are controlled by the computer system. By selectively activating one or more of the light sources, the computer system identifies correspondences that relate the 3D position of the light sources to the 2D image captured by the camera. The computer system then calculates the intrinsics of the camera using the 3D to 2D correspondences. After the intrinsics are measured, cameras may be further calibrated to in order to identify 3D locations of objects within their field of view in a presentation area. Using passive markers in a presentation area, computing system may use an iterative process that estimates the actual pose of the camera.

Claims

1. A calibration system, comprising:

a calibration apparatus comprising a plurality of light sources; and

a computing system communicatively coupled to the light sources, the computing system comprising a calibration module configured to;

selectively control the plurality of light sources to determine 3D to 2D correspondences relating 3D locations of the plurality of light sources in space to locations in a 2D image captured by a camera, and

determine intrinsic properties of the camera using the 3D to 2D correspondences.

2. The calibration system of claim 1, wherein a first light source of the plurality of light sources is a first distance from the camera along a reference axis and a second light source of the plurality of light source is a second, different distance from the camera along the reference axis.

3. The calibration system of claim 2, wherein the plurality of light sources are arranged on an inner surface of the calibration apparatus, wherein the inner surface includes a plurality of differently arranged planes.

4. The calibration system of claim 1, further comprising a mount coupled to the calibration apparatus, wherein the mount is configured to couple to the camera in order to fix a spatial relationship between the calibration apparatus and the camera.

5. The calibration system of claim 4, wherein the calibration apparatus is moveably attached to the mount such that a distance between the calibration apparatus and the camera can be adjusted.

6. The calibration system of claim 1, wherein selectively control the plurality of light sources to determine 3D to 2D correspondences further comprises:

receiving a plurality of 2D images from the camera, wherein the calibration module is configured to control the plurality of light sources such that one of;

(i) a different one of the plurality of light sources and (ii) a different grouping of the plurality of light sources is turned on during each of the plurality of 2D images, wherein a spatial relationship between the calibration apparatus and the camera is constant when each of the plurality of 2D images is captured by the camera.

7. The calibration system of claim 1, wherein the calibration module is configured to identify the 3D locations of the plurality of light sources relative to a reference point associated with the calibration apparatus.

8. The calibration system of claim 1, wherein the calibration module is configured to identify pixel locations in the 2D image corresponding to the plurality of light sources by weighting an intensity of light measured by pixels in the 2D image.

9-21. -21. (canceled)

22. A method for calibrating a camera, the method comprising:

selectively controlling a plurality of light sources to determine 3D to 2D correspondences relating 3D locations of the plurality of light sources in space to locations in a 2D image captured by the camera, wherein the plurality of light sources are mounted on a calibration apparatus in view of the camera, and

determining intrinsic properties of the camera using the 3D to 2D correspondences.

23. The method of claim 22, wherein a first light source of the plurality of light sources is a first distance from the camera along a reference axis and a second light source of the plurality of light source is a second, different distance from the camera along the reference axis.

24. The method of claim 23, wherein the plurality of light sources are arranged on an inner surface of the calibration apparatus, wherein the inner surface includes a plurality of differently arranged planes.

25. The method of claim 22, further comprising:

adjusting the spatial relationship between the calibration apparatus and the camera using a mount coupled to both the calibration apparatus and the camera.

26. The method of claim 25, wherein the calibration apparatus is moveably attached to the mount such that a distance between the calibration apparatus and the camera can be adjusted.

27. The method of claim 22, wherein selectively controlling the plurality of light sources to determine 3D to 2D correspondences further comprises:

receiving a plurality of 2D images from the camera, wherein the plurality of light sources are controlled such that one of;

(i) a different one of the plurality of light sources and (ii) a different grouping of the plurality of light sources is turned on during each of the plurality of 2D images, wherein a spatial relationship between the calibration apparatus and the camera is constant when each of the plurality of 2D images is captured by the camera.

28. The method of claim 22, further comprising:

identifying the 3D locations of the plurality of light sources relative to a reference point associated with the calibration apparatus.

29. The method of claim 22, further comprising:

identifying pixel locations in the 2D image corresponding to the plurality of light sources by weighting an intensity of light measured by pixels in the 2D image.