US 8,077,914 B1 · Optical tracking apparatus using six degrees of freedom

Abstract

This invention discloses an optical object tracking method and system with to up to six degrees of freedom: three translational and three angular coordinates. In the preferred embodiment, the system includes two near-infra-red light sources (e.g., light emitting diode), two cameras, and a digital signal processor. The system performs to tasks: object locking and tracking. For object locking and tracking, a single camera and two off-axis light sources are engaged. For more precise object tracking, two spatially-separate cameras and a single diode are used. In another embodiment, a third camera may be used to separate the locking and tracking tasks. The light sources may have different light wavelengths and may operate in a sequential mode. The cameras may be sensitive over different spectral ranges and may also differ in terms of field-of-view and resolution. The invention describes a method based on capturing images of light reflections at the camera focal plane and analyzing them, through mathematical mapping, for known locations of light sources and cameras. Invention can be adopted for the tracking of an eyeball. The related method determines an object location and orientation or a gaze vector and a point-of-regard.

Claims19

Dependent claims

A system for measuring a location and an orientation of an object of arbitrary curvature, comprising:

a first and a second light sources illuminating the object;
a first and a second cameras receiving a first and a second image of the object being illuminated by the light sources and providing a first and a second image data respectively;
and
a digital signal processing unit for receiving and analyzing the first and second image data for locating and tracking the object in real-time with six degrees of freedom, including rotational roll movement of the object around a vector from a coordinate origin to a center of the object, wherein
a real-time measurement of 3-dimensional unit vectors {ē} defines the directions between the first camera and glints from the respective sources is implemented accordingly to the system of equations:
[
e
_
s
·
n
_
s
]
=
[
(
ξ
s
⁢
e
_
s
-
A
_
s
)
·
n
_
s
]

ξ
s
⁢
e
_
s
-
A
_
s

;
wherein s is the light source number, vectors A are distances between the first camera and corresponding light source, n are normal vectors at glints from the corresponded light sources and ξ are distances from the first camera to the corresponded glints.

44 more elements

Dependencies are inferred from the claim text.

Optical tracking apparatus using six degrees of freedom

Life of this patent

Optical tracking apparatus using six degrees of freedom

Life of this patent

Abstract

Claims19