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Our Technology

 

Our patented 3D-Xense is single-camera 3D optical motion-tracking technology that optimizes the use of available camera hardware for full 6-DOF tracking   Each of our StealthTrack range of imaging sensors is high-precision individually calibrated.  It is able to track an unlimited number of trackers simultaneously.  Combined with the use of complex markers and multi-faceted tracker, our systems are able to perform fast robust tracking at sub-pixel-level accuracy better than stereovision-based dual-camera systems in terms of:

 

• Accuracy                       speed
• noise rejection             large trackable pose
• Portability                     Cost-effectiveness
•  

We also supply affordable trackers that are disposable for applications requiring moderate accuracy and containment of infection.

I. Why is single-camera better than multi-camera system for 3D tracking?

1. IT’S MORE ACCURATE

 

The main source of optical tracking error is related to the lens.  Since multi-camera system needs more lenses, the errors are cumulative and thus give a bigger error for the whole system.

 

Another source of error in multi-camera system is imperfect shuttle synchronization.  This causes erroneous matching of markers from the images if the tracker is moving.  Single-camera system does not need shuttle sync and thus has no such problem.

 

The third source of error is due to changes in relative poses of the cameras caused by thermal expansion or bending of the triangulating fixture.  If the relative poses of the cameras are different from that during calibration, the triangulation would produce erroneous result.

 

 

2. IT’S FASTER

 

Dual-camera systems require the downloading and processing of multiple images + image-matching, whereas single-camera system requires less than half of the time and resources.  This translates to higher frame rate and smaller time lag given

the same computing resources.

 

 

3. IT’S MORE ROBUST AND CAPABLE

 

Dual-camera systems require two lines-of-sight to function, and this implies that the trackable rotational pose of tracker is smaller than that for single-camera.  Its operating volume is the intersection of the two tracking volumes of the cameras and is thus smaller than that for single-camera.

 

 

4. IT’S MORE AFFORDABLE

 

A dual-camera system not only adds the cost of one more camera, but also the costs of large fixture and synchronization circuit and thus is priced typically 3 to 5 times of a single-camera system.  Single-camera system is thus more affordable in terms of price, transportation ease, maintenance and space/weight constraints.

 

5. IT’S MORE PORTABLE AND FLEXIBLE

 

Due to the need for substantial separation between the cameras for the triangulation to be sufficiently accurate, the fixture is typically 5 to 10 times the size of the camera.  This translates to expensive shipping and maintenance costs.  The system also occupies more space and is heavier in weight.  In applications where there is spatial constraints such as coordinate measuring (CMM) in tight corners, stereo-based system would have problem.  Single-camera system takes only < 20% of the space required.

II.   EXPANDABLE TO MULTI-CAMERA SETUP

 

Of course our products can be used in a multi-camera setup, and the additional cameras would provide increased robustness through redundancy of tracking from different directions.  The 3D-Xense technology just optimizes the utilization of imager hardware available.  There is also no need for rugged fixture to fix the relative poses of the cameras.

III.   USE OF COMPLEX MARKERS TO IMPROVE ACCURACY

 

Our competitors use simple spherical /circular markers which could result in inaccurate localization in case of partial occlusion.  Our trackers can also use complex /compound markers which is much more robust against noises.  This greatly improves the tracking accuracy without incurring much increase in computational requirement and markers’ size.

 

IV.    MULTI-FACETED TRACKER TO EXPAND TRACKABLE POSE

 

With the use of our tracker joints, our standard trackers can be combined to give multi-faceted tracker to expand its trackable pose.  This greatly improves the trackability of the system and overcome to a large extent the hurdle of line-of-sight problem associated with optical tracking products from other brands.

 

Inaccurate localization when simple marker is partially occluded

Enhanced localization with complex markers

Tracker

Joints

Multi-faceted Tracker