Optical Tracking
Atracsys optical pose trackers measure the position and the orientation of bodies
(subjects and/or objects) that are moving in a defined space. The bodies are observed from
multiple angles of view so that triangulating allows to calculate each bodies' locations.
In certain cases, visual markers (composed of one or several targets) are fixed to
bodies in order to improve the tracking quantitative and qualitative performances.
Atracsys proposes four different tracking technologies:
Active Tracking,
like the accuTrack
or the easyTrack localizers,
use infrared light emitting diodes (IR-LEDs) as targets observed by infrared light sensors.
IR-LEDs are pulsed sequentially and detected by three linear sensor located in the tracker.
Active Cameras,
like the infiniTrack localizer,
emit infrared light from a ring surrounding each infrared camera lens and use balls or discs as targets.
The balls or discs are coated with a retro-reflective material containing small spheres that mirror the light
back to the lenses, causing the targets to appear as bright spots in the infrared images.
Fully Passive Cameras,
like the infiniTrack localizer,
use available light in the visible spectrum to detect and pinpoint high-contrast targets printed or painted
on any suitable surface. Standard video lenses and sensors are used to capture the images, which are then fed
into the host computer or an extra computing unit for processing. Computer vision software detects the presence
of target patterns.
Markerless Passive Cameras,
like the beMerlin interactive system,
do not require wearing any kind of target of markers. Computer vision is used to extract subject's
motions and positions. Delivered measurements are in this case only raw approximations.
Pages of text and numerous studies have been dedicated to the question of whether
active optical or passive optical systems are better. A simple answer is ‘it depends’.
It is therefore important that you interpret the information presented by the different
companies within the context of how you plan to use the system; is integration with
your software solution important; your budget and your need for higher precision.
For more information about precision, click here.
Which is better?
As an example, the following product comparison chart presents in brief the major differences
between the infiniTrack passive system versus the accuTrack / easyTrack active systems:
* Depend on the tracking module used.
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