Abstract
A world-space crosshair showing the movement directions of the operator's input device tells the operator of a camera-based stage tracking or remote follow spot system, directly on the video, which way each axis of a joystick, gamepad stick, key set or 3D mouse will move the marker. In such systems the operator steers a marker, a 3D position on the stage, while watching the image of a fixed, calibrated camera; the input is mapped to stage directions by a control frame, for example fixed stage axes, a fixed bearing, the heading of the camera, or the directions that move the marker right and up in the picture. Cameras look at the stage from the front, the side or from upstage, where the picture is mirrored against the stage axes, so the same push of the stick moves the marker up, down or sideways in the picture. The crosshair at the marker keeps the familiar symmetric form of three equal lines through the output point with a ball around the crossing, but its two horizontal lines are drawn in stage coordinates along exactly the stage directions that the input axes produce under the active control frame, instead of along fixed stage axes, and the crosshair is projected into the camera image with the camera calibration. The ends of the lines carry direction markings, such as the labels of the keys and stick directions bound to them or a colour per input axis; the half of a line in the direction of the input in use is emphasised while it is held; and the lines are taken from the same mapping and the same latched state that move the marker, so the indicator and the controls cannot disagree. Drawn with a ground circle on the surface below the marker and a vertical line up to the output point, the marker is also related to the stage floor, which a crosshair alone cannot show in a flat image. Variants include arrowheads instead of labels, labels on the vertical line for the height input, a line along a path to which the marker is locked, one crosshair per controller and marker, symbols for lines pointing along the line of sight, a compass in a corner of the picture and arrows lying on the floor at the marker.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Honold, Michel and Hermann, Paul, "World-Space Crosshair Showing the Movement Directions of the Operator's Input Device in Camera-Based Stage Tracking and Remote Follow Spot Systems", Technical Disclosure Commons, ()
https://www.tdcommons.org/dpubs_series/12982