Finger tracking

To adjust the finger tracking parameters you need to activate the "Calibration" tab in the on-screen display, and click on the "Finger" item, on the right-hand side. This include a "Defaults" -button that can be used to set the finger tracking parameters to the factory defaults. Using this button does not affect the geometry calibration of the cell, only the finger tracking parameters. If the tracking sensitivity of other parameters need to be adjusted, you need to click on the "Advanced" button on the right-hand side, to get access to all the tracing parameters, as shown below.

In this view you can edit the parameters that computer vision uses to detect touches on the screen. The meanings of these parameters are listed below.

• Local contrast minumum defines how bright a fingertip should be, compared to its immediate surroundings. Lower values makes the tracking more sensitive, and higher values less sensitive. Typical value is 0.046, and it needs to be seldom adjusted.
• Required brightness: This is the most important parameter, as far as finger detection sensitivity is concerned. It defines how bright the finger tips are expected to be, in absolute terms. Due to subtle differences between the Cells, this value may need to be adjusted from the default. Lower values makes the tracking more sensitive, and higher values less sensitive. Typically this value is between 0.04, and 0.09.
• Finger classifier radius defines the expected radius of the fingertips in camera pixels. This valua is practically always set to 8. The useful range for this parameter is between 6 and 9. Smaller values indicate that the user would have smaller fingers, and larger values indicate larger fingers.
• Tracking sensitivity is a general parameter that defines how easily possible finger tips are classiied as fingers. Useful range for this parameter is between 1.0 and 1.5. There is seldom need to adjust this parameter.
• Filter drag: The raw fingertip coordinates are filtered to reduce unwanted jitter in the tracking reported coordinates. The filtering is adaptive and only applies to slow hand movements. Increasing the filter drag makes the tracking less jittery, but also slightly slower. Typical range for this parameter is between 0.9, and 1.0, although in some cases this parameter may be set to zero, to eliminate the filtering completely.
• Filter radius: The effective radius of the adaptive finger location filtering is adjusted with this parameter. Lower values indicate that the adaptation area is smaller, and higher values indicate that the adaptation area is larger. In practice this means that lower values reduce the filtering, and make the tracking react faster, while larger values make the tracking react slower. Typical range is between 20 and 50.
• Center compensation: This is an internal parameter for compensating certain lens effects and can be generally left to the default value.