TRACKING SYSTEM CALIBRATION USING OBJECT POSITION AND ORIENTATION

• US 20100302378A1
• Filed: 05/27/2010
• Published: 12/02/2010
• Est. Priority Date: 05/30/2009
• Status: Active Grant

• Current Assignee: Sony Interactive Entertainment Inc. (Sony Group Corp.)
• Original Assignee: Sony Computer Entertainment Incorporated (Sony Group Corp.)
• Inventors: Larsen, Eric, Marks, Richard Lee
• Granted Patent: US 9,058,063 B2
• Time in Patent Office: Days
• US Class Current: 348/169
• CPC Class Codes: G01S 3/7803 Means for monitoring or calibrating
• CPC Class Codes: G01S 3/784 using a mosaic of detectors
• CPC Class Codes: G06F 3/0304 Detection arrangements using opto-electronic means constructional details of pointing devices not related to the detection arrangement using opto-electronic means G06F3/033; optical digitisers G06F3/042
• CPC Class Codes: G06F 3/0346 with detection of the device orientation or free movement in a 3D space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors

Abstract

To calibrate a tracking system, a computing device receives positional data of a tracked object from an optical sensor as the object is pointed approximately toward the optical sensor. The computing device computes a first angle of the object with respect to an optical axis of the optical sensor using the received positional data. The computing device receives inertial data corresponding to the object, wherein a second angle of the object with respect to a plane normal to gravity can be computed from the inertial data. The computing device determines a pitch of the optical sensor using the first angle and the second angle.

Claims

1. A computer implemented method of calibrating a tracking system, comprising:

receiving positional data of a tracked object from an optical sensor by a computing device as the object is pointed approximately toward the optical sensor;

computing a first angle of the object with respect to an optical axis of the optical sensor using the received positional data;

receiving inertial data corresponding to the object by the computing device, wherein a second angle of the object with respect to a plane normal to gravity can be computed from the inertial data; and

determining a pitch of the optical sensor using the first angle and the second angle.

2. The method of claim 1, further comprising:

computing the second angle from the inertial data by the computing device.

3. Performing the method of claim 1 in response to receiving a calibrate command from a user while the user holds the object at a momentarily fixed position and orientation.

4. The method of claim 1, further comprising:

computing the first angle based on a focal length of the optical sensor and a vertical distance between the object and the optical axis in an image taken by the optical sensor.

5. Them method of claim 4, further comprising:

computing a relative yaw between the optical sensor and the object based on the focal length, the computed pitch and a horizontal distance between the object and the optical axis in the image.

6. The method of claim 1, further comprising:

computing a relative yaw between the optical sensor and the object concurrent to computing the pitch of the optical sensor, wherein the pitch and the yaw are computed by;

finding a first three dimensional vector that points from the optical axis to a center of the object in a reference frame of the optical sensor;

finding a second three dimensional vector that points from the optical axis to the center of the object in a world reference frame that has an axis aligned with gravity;

computing a three dimensional rotation between the first vector and the second vector; and

decomposing the three dimensional rotation into a first two dimensional rotation that represents the pitch of the optical sensor and a second two dimensional rotation that represents the relative yaw between the optical sensor and the object.

7. A computer readable storage medium including instructions that, when executed by a processing system, cause the processing system to perform a method comprising:

receiving positional data of a tracked object from an optical sensor by a computing device as the object is pointed approximately toward the optical sensor;

computing a first angle of the object with respect to an optical axis of the optical sensor using the received positional data;

receiving inertial data corresponding to the object by the computing device, wherein a second angle of the object with respect to a plane normal to gravity can be computed from the inertial data; and

determining a pitch of the optical sensor using the first angle and the second angle.

8. The computer readable storage medium of claim 7, the method further comprising:

computing the second angle from the inertial data by the computing device.

9. The computer readable storage medium of claim 7, wherein the method is performed in response to receiving a calibrate command from a user while the user holds the object at a momentarily fixed position and orientation.

10. The computer readable storage medium of claim 7, the method further comprising:

computing the first angle based on a focal length of the optical sensor and a vertical distance between the object and the optical axis in an image taken by the optical sensor.

11. Them computer readable storage medium of claim 10, the method further comprising:

computing a relative yaw between the optical sensor and the object based on the focal length, the computed pitch and a horizontal distance between the object and the optical axis in the image.

12. The computer readable storage medium of claim 7, the method further comprising:

computing a relative yaw between the optical sensor and the object concurrent to computing the pitch of the optical sensor, wherein the pitch and the yaw are computed by;

finding a first three dimensional vector that points from the optical axis to a center of the object in a reference frame of the optical sensor;

finding a second three dimensional vector that points from the optical axis to the center of the object in a world reference frame that has an axis aligned with gravity;

computing a three dimensional rotation between the first vector and the second vector; and

decomposing the three dimensional rotation into a first two dimensional rotation that represents the pitch of the optical sensor and a second two dimensional rotation that represents the relative yaw between the optical sensor and the object.

13. A tracking system, comprising:

a tracked object that includes one or more inertial sensors, the tracked object to gather inertial data as the tracked object is pointed approximately toward the optical sensor, and to transmit the inertial data to a computing device;

the optical sensor, to gather positional data of the tracked object as the object is pointed approximately toward the optical sensor, and to transmit the positional data to the computing device; and

the computing device, to receive the inertial data and the positional data, to compute a first angle of the object with respect to an optical axis of the optical sensor using the received positional data, to compute a second angle of the object with respect to a plane normal to gravity from the inertial data, and to determine a pitch of the optical sensor using the first angle and the second angle.

14. The tracking system of claim 13, wherein the computing device to receive the inertial data and the positional data, to compute the first angle and the second angle, and to determine the pitch in response to receiving a calibrate command from a user while the user holds the object at a momentarily fixed position and orientation.

15. The tracking system of claim 13, further comprising:

the computing device to compute the first angle based on a focal length of the optical sensor and a vertical distance between the object and the optical axis in an image taken by the optical sensor.

16. Them tracking system of claim 15, further comprising:

the computing device to compute a relative yaw between the optical sensor and the object based on the focal length, the computed pitch and a horizontal distance between the object and the optical axis in the image.

17. The tracking system of claim 13, further comprising:

the computing device to compute a relative yaw between the optical sensor and the object concurrent to computing the pitch of the optical sensor, wherein the pitch and the yaw are computed by;

finding a first three dimensional vector that points from the optical axis to a center of the object in a reference frame of the optical sensor;

finding a second three dimensional vector that points from the optical axis to the center of the object in a world reference frame that has an axis aligned with gravity;

computing a three dimensional rotation between the first vector and the second vector; and

decomposing the three dimensional rotation into a first two dimensional rotation that represents the pitch of the optical sensor and a second two dimensional rotation that represents the relative yaw between the optical sensor and the object.