1. A system for determining position information about a first object in a volume, comprising: a global coordinate system defined in the volume; a local coordinate system in a known fixed relationship to the first object; a pattern of two or more stripes in a fixed relationship to the first object, wherein a first stripe of the pattern is characterized by a first reference line defined relative to the local coordinate system, and a second stripe of the pattern is characterized by a second reference line defined relative to the local coordinate system; two or more cameras, wherein each camera can output a 2-dimensional video frame, and wherein each video frame has a known relationship to the global coordinate system; a digital computer adapted to receive the video frame output from each camera; and a memory connected to the computer and containing a program of instructions which cause the computer to: locate a first set of stripe images of the first stripe, wherein each image in the first set of stripe images is in the video frame output by a camera of the two or more cameras, locate a second set of stripe images of the second stripe, wherein each image in the second set of stripe images is in the video frame output by a camera of the two or more cameras, determine, for each image of the first set of stripe images, a first image line in the video frame containing the image, wherein the first image line prescribes a first plane in the volume; determine, for each image of the second set of stripe images, a second image line in the video frame containing the image, wherein the second image line prescribes a second plane in the volume; compute a first line of intersection of the first planes prescribed by at least two of the first image lines, compute a second line of intersection of the second planes prescribed by at least two of the second image lines, determine a transformation between the local coordinate system and the global coordinate system, wherein the transformation maps the first reference line to the first line of intersection, and wherein the transformation maps the second reference line to the second line of intersection, and determine from the transformation the position information about the first object.