Method and apparatus for motion tracking of an object and acquisition of three-dimensional data over large areas
A multi-dimensional solution directed to employment of a low-resolution motion tracking technique to estimate a homogeneous transformation matrix that is further adapted to accurately characterize movement/motion between successive positions of an object through time. Low-resolution tracking is first used to estimate a homogeneous transformation matrix that describes the motion between successive positions of an object as that object moves over time. The 3-dimensional imaging data is then used to calculate a more accurate homogeneous transformation matrix, providing the accuracy to better characterize motion of the object over time. In the case where the ‘object’ being tracked is a 3-dimensional imaging system (herein, 3DIS), the resulting homogeneous transformation matrix is used to create 3-dimensional digital models of the scene that is in the field-of-view of the 3-dimensional imaging system (3DIS).
1. A method for tracking motion of an object using a motion tracking system defining a global coordinate system, comprising:
(a) acquiring, with aid of a 3-D imaging system to which the object has been attached, a high-resolution three-dimensional image at a first position of successive positions of a scene under inspection and applying a first transformation matrix, generated by the motion tracking system, to locate the three-dimensional image at said first position into the global coordinate system, said 3-D imaging system and said motion tracking system in communication with a computerized controller;
(b) said first transformation matrix having been determined by combining a first transform from an object coordinate system to the global coordinate system and a transform from said 3-D imaging system to said object coordinate system;
(c) acquiring, with aid of said 3-D imaging system, a high-resolution three-dimensional image at a second position of the successive positions and applying a second transformation matrix, generated by the motion tracking system, to locate the three-dimensional image at said second position into the global coordinate system;
(d) said second transformation matrix having been determined by combining a second transform from an object coordinate system to the global coordinate system and said transform from said 3-D imaging system to said object coordinate system;
(e) establishing a cost function for addressing error comprising determining an alignment transformation matrix utilizing data from the high-resolution three-dimensional images acquired at the first and second position; and
(f) applying said alignment transformation matrix to adjust a detected position by the motion tracking system along a path of the object.
2. The method of claim 1 in which the motion tracking system utilizes an optical flow technique.
3. The method of claim 1 further comprising mounting said 3-D imaging system to which the object has been attached, to a mobile robotic vehicle.
4. The method of claim 1 in which the object which has been mounted to said 3-D imaging system and is a handheld unit; and further comprising projecting structured light to illuminate said scene under inspection.
5. The method of claim 1 in which at least one three-dimensional marker has been affixed to the object which has been mounted to said 3-D imaging system.
6. The method of claim 5 further comprising the motion tracking system obtains an estimate of motion by tracking said at least one three-dimensional marker using two-dimensional images acquired by a plurality of cameras.
7. The method of claim 1 further comprising adapting a mobile robotic vehicle to transport the 3-D imaging system to which the object has been attached.
8. The method of claim 7 further comprising: mounting said 3-D imaging system to said mobile robotic vehicle; providing wireless communication between said 3-D imaging system and said computerized controller; and providing additional capability for said mobile robotic vehicle to perform a function selected from the group consisting of welding, cleaning, cutting, and non-destructive testing.
9. The method of claim 7 further comprising providing proportional-integral-differential control tracking capability utilizing said adjusted detected position of the object for directing the motion of the mobile robotic vehicle along a pre-defined path.
10. A system for tracking motion of an object using a motion tracking system defining a global coordinate system, comprising:
(a) a 3-D imaging system to which the object has been attached, for acquiring a high-resolution three-dimensional image of a scene under inspection at a first and second position of successive positions;
(b) said 3-D imaging system and the motion tracking system in communication with a computerized controller;
(c) a first transformation matrix, generated by the motion tracking system, determined by combining a first transform from an object coordinate system to the global coordinate system and a transform from said 3-D imaging system to said object coordinate system;
(d) said first transformation matrix applied to locate the three-dimensional image acquired at said first position into the global coordinate system;
(e) a second transformation matrix, generated by the motion tracking system, determined by combining a second transform from an object coordinate system to the global coordinate system and a transform from said 3-D imaging system to said object coordinate system;
(f) said second transformation matrix applied to locate the three-dimensional image acquired at said second position into the global coordinate system;
(g) a cost function established for addressing error comprising an alignment transformation matrix utilizing data from the high-resolution three-dimensional images acquired at the first position and second position; and
(h) said computerized controller to apply said alignment transformation matrix to adjust a detected position by the motion tracking system along a path of the object.
11. The system of claim 10 wherein said 3-D imaging system to which the object has been mounted is a handheld unit; and whereby said 3-D imaging system projects structured light to illuminate said a scene under inspection.
12. The system of claim 10 in which at least one three-dimensional marker has been affixed to the object which has been mounted to said 3-D imaging system.
13. The system of claim 12 in which the motion tracking system comprises a plurality of cameras for tracking said at least one three-dimensional marker using two-dimensional images acquired by said plurality of cameras to obtain an estimate of motion.
14. The system of claim 10 further comprising a mobile robotic vehicle adapted to transport the 3-D imaging system to which the object has been attached.
15. The system of claim 14 further comprising: a wireless communication between said 3-D imaging system and said computerized controller; and a proportional-integral-differential controller to direct, utilizing said adjusted detected position of the object, the motion of said mobile robotic vehicle along a pre-defined path.