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The two key functions of optical pose trackers are:
- Detection: detect the presence of, i.e., identify, specially marked objects in the sensor's field of measurement (FOM).
- Pose measurement: report on the location and orientation of each detected object.
Both functions need to be performed repeatedly at real-time rates (10Hz or faster).
Optical pose trackers perform these functions by observing marked locations, or targets, on each tracked object from multiple angles of view, then triangulating the lines of sight to the targets to calculate each target's location. The 3-D locations of at least 3 targets are needed to calculate each object's pose, i.e., its position and orientation in space relative to the camera. Pose sensing is sometimes referred to as 6-D measurement, since at least 6 parameters are required to fully describe a pose: 3 space coordinates (X, Y, Z) and 3 orientation angles (e.g., azimuth, elevation, roll). The configuration of 3 or more targets attached to an object to allow it to be tracked is called a marker.
Validate and refine accuracy in the field
The MicronTracker camera is designed to solidly preserve the highly precise optical calibration performed at the factory. Like any other high-precision optomechanical instrument, however, its accuracy may degrade from minute changes caused by environmental stresses or rough handling.
Other position trackers on the market require customers to buy an expensive tool to verify accuracy over time. When accuracy is found to fall short of requirements, the camera needs to be sent back to the factory for repair or recalibration. MicronTracker’s R-Fine is the first solution that allows users to not only verify, but also to immediately restore the device’s accuracy. Furthremore, R-Fine is included free of charge in every MicronTracker kit.
R-Fine’s software contains a model of the typical physical changes occuring in the mechanical structure of the camera. During the procedure, the model is adjusted to best match the data collected. The adjusted model is then used to refine the camera’s calibration. |
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Easy to use
R-Fine kit includes a custom-made accuracy bar and the required software. To perform the refinement, the bar is positioned in different regions and orientations within the field of measurement. The R-Fine software guides the user during the procedure with easy to follow instructions, using the video images to show the user where and how the bar should be positioned. The augmented reality guidance graphics are overlaid as a semi-transparent layer, leaving a full perception of the visual field. A final report explains in simple terms the results of the procedure and gives the user the option to save the refinement in the calibration file. The R-Fine procedure typically requires only five minutes, making it practical to validate the accuracy performance as frequently as desired. |
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