IP Library Granted Patent US 11,423,573
Granted Patent B2
US 11,423,573 · App. 16/854,486 · Granted Aug 23, 2022

System and methods for calibrating cameras with a fixed focal point

Inventors: Zhijia Yuan (Bethel Park, PA); Randyll Mark Cash, II (Pittsburgh, PA); Danny Hongyu Lu (Lexington, MA); David Golladay (Pittsburgh, PA); Michael Vinent Praskovich (Pittsburgh, PA); Benjamin David Himes (Dayton, PA); Armen Berberian (Pittsburgh, PA)
Assignee: UATC, LLC
G06T7/80G06T7/571G06T2207/30208G06T2207/30252
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Quick Facts
Patent No.
US 11,423,573
App. No.
16/854,486
Granted
Aug 23, 2022
Kind
B2
Abstract

The present disclosure is directed to a system for calibrating cameras with a fixed focal point. In particular, a camera calibration system comprising one or more computing devices can project a plurality of fiducial markers on a target surface using the plurality of collimators. The camera calibration system can capture, using the camera, a plurality of images of the target surface with the camera, wherein the camera is rotated between each captured image in the plurality of images. The camera calibration system can compare the plurality of images with a ground truth projection. The camera calibration system can generate calibration data based on the comparison of the plurality of images with the ground truth projection. The camera calibration system can store the calibration data for use in rectifying the camera.

Claims (51)

1. A computer-implemented method for camera rectification by a camera testing system comprising a plurality of collimators and a camera, the method comprising:

projecting, by the camera testing system, a plurality of fiducial markers on a target surface using the plurality of collimators;

capturing, by the camera testing system and using the camera, a plurality of images of the target surface with the camera, wherein the camera is rotated between each captured image in the plurality of images;

comparing, by the camera testing system, the plurality of images with a ground truth projection;

generating, by the camera testing system, calibration data based on the comparison of the plurality of images with the ground truth projection; and

storing, by the camera testing system, the calibration data for use in rectifying the camera.

2. The computer-implemented method of claim 1 , wherein a fiducial marker is a circular target image.

3. The computer-implemented method of claim 2 , wherein the fiducial marker includes a discoverable center point.

4. The computer-implemented method of claim 2 , wherein the calibration data includes a camera data matrix and a list of distortion coefficients.

5. The computer-implemented method of claim 1 , wherein the plurality of collimators project the plurality of fiducial markers such that the fiducial markers have an infinite focus.

6. The computer-implemented method of claim 1 , wherein the camera has a fixed focal point.

7. The computer-implemented method of claim 6 , wherein the fixed focal point is fixed at an infinite distance.

8. The computer-implemented method of claim 1 , wherein projecting a plurality of fiducial markers on a target surface using the plurality of collimators further comprises:

determining, by the camera testing system, current angle data for the plurality of collimators; and

generating, by the camera testing system, a ground truth projection by mathematically projecting a plurality of fiduciary markers onto a virtual surface using the current angle data for the plurality of collimators.

9. The computer-implemented method of claim 8 , wherein the ground truth projection describes a location of a plurality of fiducial markers on a virtual surface, each fiducial marker being associated with one or more target points.

10. The computer-implemented method of claim 1 , wherein comparing the plurality of images with the ground truth projection further comprises:

analyzing, by the camera testing system, the plurality of images to determine a plurality of fiducial markers within the images; and

generating, by the camera testing system, a reference grid using the plurality of fiducial markers.

11. The computer-implemented method of claim 10 , wherein determining a plurality of fiducial markers further comprises:

identifying, by the camera testing system, one or more fiducial markers in the captured images;

for each identified fiducial marker, identifying, by the camera testing system, a center of the fiducial marker as a target point.

12. The computer-implemented method of claim 11 , wherein comparing the plurality of images with the ground truth projection further comprises:

comparing, by the camera testing system, the reference grid with the ground truth projection.

13. The computer-implemented method of claim 12 , wherein generating calibration data based on the comparison of the plurality of images with the ground truth projection further comprises:

determining, by the camera testing system, a degree and direction of distortions between the ground truth projection and the reference grid; and

generating, by the camera testing system, calibration data based on the degree and direction of distortions between the ground truth projection and the reference grid.

14. The computer-implemented method of claim 1 , wherein the camera is rotated around its entrance pupil.

15. A camera testing system comprising:

a plurality of collimators configured to project a plurality of fiducial markers on a target surface;

a camera with a fixed focal point configured to capture images of the target surface; and

a testing control system configured to:

rotate the camera while capturing a plurality of images of the target surface;

compare the plurality of images with a ground truth projection;

generate calibration data based on the comparison of the plurality of images with the ground truth projection; and

store the calibration data for use in rectifying the camera.

16. The camera testing system of claim 15 , wherein the testing control system is further configured to:

generate a ground truth projection, wherein generation of the ground truth projection comprises:

determining current angle data for the plurality of collimators; and

generating a ground truth projection by mathematically projecting a plurality of fiduciary markers onto a virtual surface using the current angle data for the plurality of collimators.

17. The camera testing system of claim 16 , wherein the ground truth projection describes a location of a plurality of fiducial markers on a virtual surface, each fiducial marker being associated with one or more target points.

18. The camera testing system of claim 15 , wherein the plurality of collimators project fiducial markers such that the fiducial markers are focused on infinity.

19. A camera testing device, the device comprising:

a plurality of collimators configured to project a plurality of fiducial markers on a target surface;

a camera with a fixed focal point configured to capture a plurality of images of the target surface from a plurality of rotation angles; and

a control system, the control system comprising processors and memory, the memory storing instructions that, when executed by one or more computing devices, cause the control system to perform operations, the operations comprising:

rotating the camera while capturing a plurality of images of the target surface;

comparing the plurality of images with a ground truth projection;

generating calibration data based on the comparison of the plurality of images with the ground truth projection; and

rectifying the camera based on the calibration data.

20. The camera testing device of claim 19 , wherein the plurality of collimators project the plurality of fiducial markers such that the fiducial markers have an infinite focus.

Assignments (2)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Jun 14, 2024
From: UATC, LLC
To: AURORA OPERATIONS, INC.
Reel/Frame 067733/0001 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Dec 29, 2020
From: YUAN, ZHIJIA; CASH, RANDYLL MARK, II; LU, DANNY HONGYU; GOLLADAY, DAVID; PRASKOVICH, MICHAEL VINCENT; HIMES, BENJAMIN DAVID; BERBERIAN, ARMEN
To: UATC, LLC
Reel/Frame 054768/0208 →