Apparatus and methods process a set of calibration sample values acquired in response to a sequence of calibration touch events generated at known X-Y coordinate positions along a linear path across a touch panel surface. The set of calibration sample values is then curve-fitted to the path to create a characteristic model of the touch panel or a portion thereof. Run-time signals are acquired from X-Y nodes across the panel at the time of a touch event. One or more run-time signal values may be substituted into the panel characteristic model to determine a distance between an X-Y node most strongly associated with the run-time touch event and a point-of-projection of the touch event location onto the path.