1. A system for detecting a plurality of objects on a touch sensitive surface, said system comprised of: a plurality of electrodes forming a sensor grid for detecting a presence of at least two objects on the touch sensitive surface, said plurality of electrodes forming a quadrilateral having four edges; means for detecting a presence of at least two objects on the touch sensitive surface; means for collecting data beginning from each of the four edges and moving towards an opposite edge and for stopping data collection when an object is detected; and means for determining the boundaries of a perimeter formed by the at least two objects by using the collected data from each of the four edges.