Path Networks for Remote-Operated Follow Spots

In stage tracking and remote follow spot systems, an operator steers a marker, a position on the stage that is sent to lights, media and audio systems, while watching a calibrated camera image. Letting that position move only along a stored line is the obvious and widely used answer to routes that performers repeat: it is the digital form of a follow spot whose tilt is locked or whose yoke runs in a guide, and it is known from camera tracks, virtual rails and CAD snapping, and guide lines onto which the target is snapped by a button are a standard function of widely used follow-spot and tracking systems. The known form, typically a straight line between two stored points, does not fit routes of arbitrary shape, nor performers whose route is unpredictable, such as a singer who chooses spontaneously which aisle of the auditorium to walk down. This disclosure describes what is added to the known basis in a working system to solve these problems. Paths are polylines of 3D points whose height is the height of the output point, so that a marker on a ramp or platform takes its height from the path. Corners are rounded by arcs that lie in the plane of both segments, so that changes of height are rounded as well. Paths that cross in plan at the same height, or whose ends touch another path, form a network without any junction being defined by hand. At a junction the marker takes the way that matches the operator's push best, but leaves its own path only when another way is clearly better, within a switch area that grows with speed. Only the component of the push along the path moves the marker. Locking is a soft pull during which the input keeps moving the marker. Each end of a path either holds the marker or releases it. Absolute positions from network messages, person detection or an assisted output are projected onto the part of the network the marker can reach, so that no output ever leaves the path. Recording, display in the camera image and control over the network complete the example. Variants are described.