A touch system includes a touch-sensitive surface with emitters and detectors arranged around its periphery. A touch event caused on an object interacts with optical beams that propagate from the emitters along the touch-sensitive surface to the detectors. Beam data indicating detected intensities of the optical beams is received. The touch system determines a set of measured interactions of the optical beams with the detected touch event from the beam data and compares the set of measured interactions with sets of model interactions of the optical beams for different candidate touch feature sets. Based on the comparison, the touch system selects one of the candidate touch features sets for the touch event. The touch system may also classify the touch event as having been caused by a particular object (or class of object) based on the selected touch feature set.
Touch object discrimination by characterizing and classifying touch events