1. A method for displaying three-dimensional workcell data comprising the steps of: providing from a data source 3-D workcell data representing a model of a robot and associated components in a workcell; providing a hand-held display device and placing the display device in data communication with the data source; communicating the workcell data from the data source to the display device; generating a 3-D visual representation of the workcell data on the display device, including displaying the visual representation of a position of the robot based on a value of a program or a non-program representation of robot position within a software program for controlling the robot, an aggregate space occupied by the robot through movement of an associated part of the robot about at least one axis of rotation of the robot throughout execution of at least a portion of the software program, and an interference visualization image of the aggregate space that includes an image of a plane transverse to the axis of rotation; and operating the display device to manipulate the visual representation.