A touch system comprises overlapping coordinate input sub-regions defining a generally contiguous input surface. Each coordinate input sub-region generates pointer coordinate data in response to pointer contacts thereon. When a pointer contact is made on a region of a coordinate input sub-region that overlaps with an adjacent coordinate input sub-region, each overlapping coordinate input sub-region processes acquired images to derive pointer data and triangulates the position of the pointer using the derived pointer data. Thereafter, the triangulated positions generated by the overlapping coordinate input sub-regions are processed in accordance with defined logic thereby to determine the position of the pointer contact relative to the touch surface.