All Pages
Adjusting marker tracking

There are minor differences between the infrared sensitivy of the Cells, so it may be necessary to adjust the sensitivity of the tracking algorithm. To adjust the sensitivity, navigate to Calibration => Circles menu and click on the "Advanced" button to get access to all the marker tracking parameters.

In the advanced view there are series of sliders that can be adjusted, related to the tracking. Only a couple of these are useful for end user calibration. The most important parameters are:

  1. Luminosity threshold
  2. Maximum length of the contour
  3. Strictness

Below is the meaning of these parameters, including the ones which are more seldom used.

  • Luminosity threshold (brightness of the while areas) is the most important value for marker tracking. It controls the expected brightness of the white areas of the markers. Typical range is 30 to 60. Values that are too high or too low will cause poor tracking.
  • Maximum length of the contour relates to the size of the markers. Larger values indicate larger markers, and smaller values indicate smaller markers. For typical applications, the default length (150 pixels) is a good setting.
  • Minimum length of the contour (relative to the maximum length) controls the minimum size of the marker. This is a value between 0.0 and 1.0. Lower values mean that the markers can be very different sizes, while higher values indicate that the markers must have a more constant size. Typical range for this parameter is .15 t o 0.8, although very low values seldom cause problems for the tracking. Values too close to 1.0 may cause poor tracking. There is seldom a need to adjust this parameter.
  • The number of knots between intervals for corner detection is an internal parameter related to the detection of corner points of the markers. Typical values are between 5 and 10. For smaller markers, smaller values need to be used.
  • Select between interior and exterior modes is an internal parameter related to making markers with inverted edge detection colors
  • Strictness defines how closely the circle must resemble a circle. Lower values allow the detector to detect shapes which are further away from from the normal circle shape. Default value is 0.7.
  • Radius multiplier for the found circle fine-tunes the tracking parameters for locating the rings with the information bits.