Insufficient touch distance!

[alborz]

Hi,

I have a LeapMotion mounted above a large monitor screen (a couple of cm in front of the actual screen).

I am using the touch_distance value to do some calculation.
The touch_distance value works very well when it detects a pointable ~25-30 cm directly below the LeapMotion Device. I get a reading from 0.5 to -0.3.

On the other hand if the pointable is a bit further away from the LeapMotion, the lower limit of the touch_distance starts to increase. Approximately 40-50cm away from the LeapMotion the lowest value returned by touch_distance is 0.33.

What am I missing here? Is this expected behavior? How should I calculate if the pointable is close to touching the screen.

    frame = controller.frame()
    pointable = frame.pointables.frontmost
    
    if pointable.is_valid:
        zone = pointable.touch_distance

[Joe_Ward]

Two points to consider:

1. We don't support mounting the device top down. Typically there is too much interference from background clutter from the nearby table or desk.

2. The touch_distance value uses an adaptive heuristic that calculates a moving touch "plane" based on the user's hand motion. It isn't really appropriate for a plane with a fixed position, like a monitor. For that you would need a location/calibration routine that you can use to pinpoint the monitor's location in space. You could also used a fixed mount and measure the offset of the screen from the Leap Motion origin mechanically.