An illumination structure for an interactive input system having a display surface and a light source for backlighting the display surface is provided. The illumination structure includes at least one redirection structure positioned with respect to the display surface to receive excess light produced by the light source and to redirect the excess light generally across the display surface for backlighting one or more pointers. A method is provided for determining the location of at least one pointer in an interactive input system. The method includes capturing images generally across a display surface of a region of interest and a reflection of the region of interest; examining the images to determine at least one first potential target location for at least one pointer that is within the region of interest; analyzing the at least one first potential target location to resolve at least one first true target location associated with the at least one pointer; and calculating a first location for the at least one pointer corresponding to the at least one first true target location.