Notice that the example inverts the y-axis by subtracting the normalized y coordinate from one before multiplying by the maximum height.
If you are using pointable or palm positions in a 2D application, consider using the Pointable.StabilizedTipPosition or Hand.StabilizedPalmPosition. These attributes have extra stabilization and filtering to help the user interact with a 2D interface. For 3D applications, the unstabilized Pointable.TipPosition and Hand.PalmPosition are usually more suitable.