US-12618952-B2 - Staging system to verify accuracy of a motion tracking system

US12618952B2US 12618952 B2US12618952 B2US 12618952B2US-12618952-B2

Abstract

A staging system has to be calibrated to determine a location of a horizontal pivot axis of a target frame. A stage calibration light beam is generated and reflected from a target frame mirror. The target frame is pivoted between first and second positions and the locations of the stage calibration light beam are detected. The locations of the stage calibration light beam provide a value representing an orientation of the target frame mirror relative to the horizontal pivot axis. The orientation of the target frame mirror is then adjusted based on the value so that the target frame mirror is more normal to the horizontal pivot axis.

Inventors

Jason Robert Wither
Eldar Khaliullin

Assignees

MAGIC LEAP, INC.

Dates

Publication Date: 20260505
Application Date: 20191008

Claims (17)

1 . A method of detecting an object comprising: (i) calibrating a staging system, including: positioning a mobile platform of the staging system in a first stationary position within a staging area; generating a stage calibration light beam; transmitting the stage calibration light beam from a target frame of the staging system mounted to the stationary platform; reflecting the stage calibration light beam from a target frame mirror; pivoting the target frame about a pivot axis between a first pivot angle and a second pivot angle relative to the mobile platform; detecting first and second locations of the stage calibration light beam after the stage calibration light beam is reflected from the target frame mirror when the target frame is in the first pivot angle and in the second pivot angle respectively; determining, based on the first and second locations, a value representing an orientation of the target frame mirror relative to the pivot axis; and adjusting, based on the determination of the value representing the orientation of the target frame mirror, the orientation of the target frame mirror relative to the target frame so that the target frame mirror is more normal to the pivot axis.
2 . The method of claim 1 , wherein the stage calibration light beam is a laser beam.
3 . The method of claim 1 , further comprising: generating a primary calibration light beam; splitting the primary calibration light beam into a reference calibration light beam and the stage calibration light beam; detecting a location of the reference calibration light beam and a location of the stage calibration light beam; and adjusting an orientation of the target frame so that the location of the stage calibration light beam coincides with the location of the reference calibration light beam.
4 . The method of claim 3 , wherein a beam splitter splits the primary calibration light beam.
5 . The method of claim 4 , wherein the beam splitter splits the primary calibration light beam based on intensity.
6 . The method of claim 1 , further comprising: (ii) using the staging system to generate a stage-based location of a beacon.
7 . The method of claim 6 , further comprising: generating a stage positioning light beam; reflecting the stage positioning light beam from the target frame mirror; detecting a location of the stage positioning light beam after the stage positioning light beam is reflected from the target frame mirror; and determining a stage-based location of the beacon on the target frame based on the stage positioning light beam.
8 . The method of claim 6 , wherein using the staging system to generate a stage-based location of a beacon, includes: moving the staging system and positioning the mobile platform of the staging system in a second stationary position within the staging area; detecting a location of the stage positioning light beam after moving the staging system and the stage positioning light beam is reflected from the target frame mirror; and determining a stage-based location of the beacon on the target frame based on the stage positioning light beam after moving the staging system.
9 . The method of claim 8 , wherein the staging system is moved in a direction of the stage positioning light beam.
10 . The method of claim 9 , further comprising: adjusting an orientation of the target frame relative to the mobile platform after moving the mobile platform to adjust a location of the stage positioning light beam.
11 . The method of claim 6 , wherein the stage positioning light beam is a laser beam.
12 . The method of claim 6 , further comprising: (iii) operating a motion tracking system to generate a motion tracking system-based location of the beacon, including: detecting, with at least one detector, the beacon and a value of the beacon relative to the detector; and determining, with a motion tracking system positioning algorithm a motion tracking system-based location of the beacon relative to the motion tracking system.
13 . The method of claim 12 , wherein operating the motion tracking system to generate a motion tracking system-based location of the beacon includes: swiveling the target frame about a vertical swivel axis relative to the mobile platform; detecting, with at least one detector, the beacon and a value of the beacon relative to the detector after swiveling the target frame relative to the mobile platform; and determining, with a motion tracking system, positioning algorithm a motion tracking system-based location of the beacon relative to the motion tracking system-based on the value of the beacon relative to the detector.
14 . The method of claim 12 , further comprising: (iv) verifying the motion tracking system, including: comparing the motion tracking system-based location with the stage-based location to determine accuracy of the motion tracking system-based location.
15 . A method of detecting an object comprising: (i) calibrating a staging system, including: generating a stage calibration light beam; reflecting the stage calibration light beam from a target frame mirror; pivoting a target frame about a pivot axis between a first pivot angle and a second pivot angle relative to a mobile platform; detecting first and second locations of the stage calibration light beam after the stage calibration light beam is reflected from the target frame mirror when the target frame is in the first pivot angle and in the second pivot angle respectively; determining, based on the first and second locations, a value representing an orientation of the target frame mirror relative to the pivot axis; and adjusting, based on the determination of the value representing the orientation of the target frame mirror, the orientation of the target frame mirror relative to the target frame so that the target frame mirror is more normal to the pivot axis; (ii) using the staging system to generate a stage-based location of a beacon, including: generating a stage positioning light beam; reflecting the stage positioning light beam from the target frame mirror; detecting a location of the stage positioning light beam after the stage positioning light beam is reflected from the target frame mirror; and determining a stage-based location of the beacon on the target frame based on the stage positioning light beam; (iii) operating a motion tracking system to generate a motion tracking system-based location of the beacon, including: detecting, with at least one detector, the beacon and a value of the beacon relative to the detector; determining, with a motion tracking system, positioning algorithm a motion tracking system-based location of the beacon relative to the motion tracking system-based on the value of the beacon relative to the detector; and (iv) verifying the motion tracking system, including: comparing the motion tracking system-based location with the stage-based location to determine accuracy of the motion tracking system-based location.
16 . An object detection system comprising: (i) a staging system that includes: a mobile platform; a target frame mounted to the mobile platform for pivotal movement about a pivot axis between a first pivot angle and a second pivot angle; a beacon on the target frame; a target frame mirror attached to the target frame; at least one light source generating a stage calibration light beam, for reflection from the target frame mirror, first and second locations of the stage calibration light beam after the stage calibration light beam is reflected from the target frame mirror being detectable when the target frame is in the first pivot angle and in the second pivot angle respectively, based on the first and second locations, a value being calculable representing an orientation of the target frame mirror relative to the pivot axis; a mirror orientation adjustment mechanism between the target frame mirror and the target frame to adjust, based on the determination of the value representing the orientation of the target frame mirror, the orientation of the target frame mirror so that the target frame mirror is more normal to the pivot axis, the at least one light source generating and reflecting a stage positioning light beam from the target frame mirror, a location of the stage positioning light beam after the stage positioning light beam is reflected from the target frame mirror being detectable; and a stage location algorithm to determine a stage-based location of the beacon on the target frame based on the stage positioning light beam; and (ii) a motion tracking system that includes: at least one detector positioned to detect the beacon and a value of the beacon relative to the detector; and a motion tracking system positioning algorithm for receiving the value of the beacon relative to the detector as an input, the motion tracking system positioning algorithm to determine a motion tracking system-based location of the beacon relative to the motion tracking system as an output from the motion tracking system positioning algorithm for comparing the motion tracking system-based location with the stage-based location to determine accuracy of the motion tracking system-based location.
17 . The method of claim 16 , wherein the mobile stage includes: a frame adjustment mechanism between the mobile platform and the target frame to adjust an orientation of the target frame relative to the mobile platform.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a National Phase of International Application No. PCT/US2019/055185, filed on Oct. 8, 2019, which claims priority from U.S. Provisional Patent Application No. 62/745,218, filed on Oct. 12, 2018 and U.S. Provisional Patent Application No. 62/798,294, filed on Jan. 29, 2019, all of which are incorporated herein by reference in their entirety. BACKGROUND TO THE INVENTION 1). Field of the Invention This invention relates to an object detection system having a staging system that is used to verify accuracy of a motion tracking system. 2). Discussion of Related Art Computers are used to created two-dimensional and three-dimensional renderings of real world objects. For example, computer games have two-dimensional and three-dimensional renderings of athletes and other humans that appear lifelike and move in a lifelike manner. The way that these objects move is often pre-recorded using a motion tracking system. A motion tracking system may have a staging area where an athlete is located. A plurality of cameras are positioned around the athlete and are used to capture the locations of beacons that are attached to clothing worn by the athlete as the athlete performs a series of moves such as striking a golf ball, catching a football, etc. The motion tracking system has a motion tracking system positioning algorithm that receives data from the cameras and determines the locations of the beacons. These locations are then recorded and are used to match a rendering of an athlete in a moving computer model. It has become increasingly important that the motion tracking system record the locations of these beacons accurately. For purposes of accurately recording the movement of body parts of an athlete, the locations of the beacons relative to one another should be accurate. It is also very important that relative location of beacons does not change as an object (such as a human) is moving through space. For example, in the case of an athlete that is being captured, it is important that length and angles of arms or joints do not change as an athlete is moving across a large area and such errors tend be more pronounced when a large area is used for motion tracking. Furthermore, the locations of the beacons should be accurately determined relative to other real world objects. It is, for example, important that location of the athlete relative to the ground be accurate so that the athlete moves across the ground as opposed to floating above the ground or below it SUMMARY OF THE INVENTION The invention provides a method of detecting an object including (i) calibrating a staging system, including generating a stage calibration light beam, reflecting the stage calibration light beam from a target frame mirror, pivoting a target frame about a pivot axis between a first pivot angle and a second pivot angle relative to a mobile platform, detecting first and second locations of the stage calibration light beam after the stage calibration light beam is reflected from the target frame mirror when the target frame is in the first pivot angle and in the second pivot angle respectively, determining, based on the first and second locations, a value representing an orientation of the target frame mirror relative to the pivot axis and adjusting, based on the determination of the value representing the orientation of the target frame mirror, the orientation of the target frame mirror relative to the target frame so that the target frame mirror is more normal to the pivot axis. The invention also provides a method of detecting an object including (i) calibrating a staging system, including generating a stage calibration light beam, reflecting the stage calibration light beam from a target frame mirror, pivoting a target frame about a pivot axis between a first pivot angle and a second pivot angle relative to a mobile platform, detecting first and second locations of the stage calibration light beam after the stage calibration light beam is reflected from the target frame mirror when the target frame is in the first pivot angle and in the second pivot angle respectively, determining, based on the first and second locations, a value representing an orientation of the target frame mirror relative to the pivot axis and adjusting, based on the determination of the value representing the orientation of the target frame mirror, the orientation of the target frame mirror relative to the target frame so that the target frame mirror is more normal to the pivot axis; (ii) using the staging system to generate a stage-based location of a beacon, including generating a stage positioning light beam, reflecting the stage positioning light beam from the target frame mirror, detecting a location of the stage positioning light beam after the stage positioning light beam is reflected from the target frame mirror and determining a stage-based location of the beacon on the target frame based on the stage p