TRUE SPACE TRACKING OF AXISYMMETRIC OBJECT FLIGHT USING DIAMETER MEASUREMENT

• US 20140301598A1
• Filed: 06/18/2013
• Published: 10/09/2014
• Est. Priority Date: 04/03/2013
• Status: Active Grant

• Current Assignee: Pillar Vision Incorporated
• Original Assignee: Pillar Vision Incorporated
• Inventors: MARTY, Alan W., Carter, John
• Granted Patent: US 8,948,457 B2
• Time in Patent Office: Days
• US Class Current: 382/103
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/30224 Ball; Puck
• CPC Class Codes: G06T 2207/30241 Trajectory
• CPC Class Codes: G06T 7/246 using feature-based methods, e.g. the tracking of corners or segments
• 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 23/51 Housings

Abstract

Methods and apparatus for determining a trajectory of a axisymmetric object in 3-D physical space using a digital camera which records 2-D image data are described. In particular, based upon i) a characteristic length of the axisymmetric object, ii) a physical position of the camera determined from sensors associated with the camera (e.g., accelerometers) and iii) captured 2-D digital images from the camera including a time at which each image is generated relative to one another, a position, a velocity vector and an acceleration vector can be determined in three dimensional physical space for axisymmetric object objects as a function of time. In one embodiment, the method and apparatus can be applied to determine the trajectories of objects in games which utilize axisymmetric object objects, such as basketball, baseball, bowling, golf, soccer, rugby or football.

Claims

1. A non-transitory computer readable medium for storing a computer program used by a computing device, the computer program executed by the computing device to generate a three dimensional (3-D) trajectory of an axisymmetric object from two dimensional (2-D) digital image data, the computer readable medium comprising:

computer code for receiving a sequence of 2-D digital images from a digital camera associated with the computing device;

computer code for receiving orientation data which is used to determine or to specify an orientation of a lens of the digital camera in 3-D physical space, said lens configured to receive light used to generate the 2-D digital images;

computer code for transforming pixel data in each of the 2-D digital images based upon the determined orientation of the lens;

computer code for identifying a 2-D representation of an axisymmetric object captured in the transformed pixel data associated with each of the 2-D digital images;

computer code for determining pixel coordinates of the 2-D representation of the axisymmetric object in each of the 2-D digital images;

computer code for determining a characteristic length of the 2-D representation of the axisymmetric object measured in pixels in each of the 2-D digital images wherein the characteristic length of the 2-D representation varies within the sequence of the 2-D digital images;

computer code for determining a distance to the identified 2-D representation of the axisymmetric object from the lens based upon the characteristic length in the pixels, said distance measured in units associated with 3-D physical space; and

computer code for determining 3-D coordinates of the axisymmetric object as a function of time in the 3-D physical space based upon the determined distance and the pixel coordinates of the 2-D representation of the axisymmetric object captured in the transformed pixel data associated with each of the 2-D digital images.

2. The computer readable medium of claim 1, wherein the axisymmetric object is a spherically shaped object used in a game.

3. The computer readable medium of claim 2, wherein the characteristic length is a diameter of a circle.

4. The computer readable medium of claim 1, wherein the axisymmetric object is a football having an elliptically shaped cross section.

5. The computer readable medium of claim 4, wherein the characteristic length is a minor axis of an ellipse.

6. The computer readable medium of claim 1, further comprising computer code for identifying one or more secondary objects associated with a play of a game captured in the transformed pixel data associated with each of the 2-D digital images.

7. The computer readable medium of claim 6, further comprising computer code for receiving input from a touch screen display wherein the input from the touch screen display is used to identify the one or more secondary objects.

8. The computer readable medium of claim 3, further comprising computer code for determining a second distance, measured in the units of the 3-D physical space, to the identified one or more secondary objects from the lens.

9. The computer readable medium of claim 5, further comprising computer code, based upon at least the second distance, for determining the 3-D coordinates of the one or more secondary objects in the 3-D physical space.

10. The computer readable medium of claim 1, further comprising computer code for receiving a pixel resolution of the 2-D digital images.

11. The computer readable medium of claim 10, wherein the physical distance is determined based upon the received pixel resolution.

12. The computer readable medium of claim 1, further comprising computer code for receiving or retrieving the characteristic length of the axisymmetric object measured in the units associated with the 3-D physical space.

13. The computer readable medium of claim 1, wherein the orientation data is received from one or more sensors located on the computing device.

15. The computer readable medium of claim 1, wherein the 2-D representations of the axisymmetric object in the 2-D digital images is captured while the axisymmetric object is in one or more of free flight, rolling along a surface, in contact with a surface, being held in person'"'"'s hands and combinations thereof.

16. The computer readable medium of claim 1, wherein the function of the time of the 3-D coordinates is based upon a time associated with each of the 2-D digital images.

17. The computer readable medium of claim 1, further comprising computer code for receiving a recording speed of the camera wherein the recording speed is used to determine the function of the time of the 3-D coordinates.

18. The computer readable medium of claim 1, further comprising computer code for determining a velocity vector and magnitude of the velocity vector as the function of time in the 3-D physical space.

19. The computer readable medium of claim 1, further comprising computer code for generating and outputting a first 2-D digital image including a trajectory curve which connects a plurality of positions of the axisymmetric object wherein the trajectory curve is rendered from the determined 3-D coordinates of the axisymmetric object as the function of the time in the 3-D physical space.

20. The computer readable medium of claim 19, wherein the first 2-D digital image further includes a graphical representation of one or more of a playing field, playing field markings and/or secondary objects associated with a play of a game in which the spherical object is used, said graphical representation rendered from 3-D models of the playing field, playing field marking and/or secondary objects in the 3-D physical space.

21. The computer readable medium of claim 20, further comprising computer code for identifying a portion of the playing field, playing field markings and/or secondary objects in the sequence of the 2-D digital images wherein the graphical representation includes an additional portion of the playing field, playing field markings and/or secondary objects not identified in the sequence of the 2-D digital images.

22. The computer readable medium of claim 1, further comprising computer code for a simulation of a trajectory of the axisymmetric object in 3-D in physical space wherein the simulation is used to predict second 3-D coordinates of the axisymmetric object as the function of time in the 3-D physical space using the 3-D coordinates as the function of the time determined from the 2-D digital images as initial conditions for the simulation.

23. The computer readable medium of claim 22, wherein the predicted second 3-D coordinates of the axisymmetric object are used to extrapolate a trajectory of the axisymmetric object in the 3-D physical space determined from the sequence of the 2-D digital images.

24. The computer readable medium of claim 1, further comprising computer code for generating trajectory information associated with a trajectory of the axisymmetric object in the 3-D physical space determined from the sequence of the 2-D digital images.

25. The computer readable medium of claim 24, wherein the trajectory information is used as input for a video game.

26. The computer readable medium of claim 24, where the trajectory information is used to develop training recommendations for improving performance of a participant in a game played using the axisymmetric object.

14. The computer readable medium of 13 wherein the one or more sensors includes an accelerometer.

27. A non-transitory computer readable medium for storing a computer program used by a computing device, the computer program executed by the computing device to generate a three dimensional (3-D) trajectory of an axisymmetric object from two dimensional (2-D) digital image data, the computer readable medium comprising:

computer code for receiving a sequence of 2-D digital images from a digital camera associated with the computing device;

computer code for receiving orientation data which is used to determine or to specify an orientation of a lens of the digital camera in 3-D physical space, said lens configured to receive light used to generate the 2-D digital images;

computer code for transforming pixel data in each of the 2-D digital images based upon the determined orientation of the lens;

computer code for identifying a 2-D representation of an axisymmetric object and at least one secondary object captured in the transformed pixel data associated with each of the 2-D digital images;

computer code for determining pixel coordinates of the 2-D representation of the axisymmetric object and the secondary object in each of the 2-D digital images;

computer code for determining a characteristic length of the 2-D representation of the at least one secondary object measured in pixels in each of the 2-D digital images;

computer code for determining a distance to the identified 2-D representation of the secondary object from the lens based upon the characteristic length in the pixels, said distance measured in units associated with 3-D physical space; and

computer code for determining 3-D coordinates of the axisymmetric object as a function of time in the 3-D physical space based upon the determined distance and the pixel coordinates of the 2-D representation of the axisymmetric object captured in the transformed pixel data associated with each of the 2-D digital images.