measuring instruments for use in motion picture film and video animation techniques, having one or more source units for emitting multidimensional magnetic fields and one or more sensor units adapted for affixation to one or more parts of an actor's anatomy for sensing the multidimensional magnetic fields emitted by the source unit(s), and an electronic unit for processing the output of the sensor unit(s) to determine the position and orientation of the sensor unit(s) and, thus, the position ...