Tracking

Active marker

A physical reference for tracking purposes with a unique i.d. such as a strobing LED bulb.

Camera tracking

The process of tracking the camera’s position in physical space in order to coordinate its movements with content displayed by the real-time engine.

Degrees of freedom (DoF)

The number of dimensions an object or headset can move or be tracked in 3D space. A 3 DoF system can track position or orientation, but not both simultaneously, while a 6 DoF system can track position and orientation simultaneously.

Depth compositing

The use of machine vision or other techniques to derive a depth matte which can then be used to realistically composite elements live for simulcam or other visualization purposes. Can be advantageous when compared to earlier chromakey type compositing techniques.

Inside-out tracking

A method of camera tracking which uses a sensor mounted directly on the camera and searches for trackable features such as markers in the ceiling or a map of the physical set using machine vision techniques. See also outside-in tracking.

Latency

The delay between when a signal is sent, passes through all of the equipment in the signal flow, and is received at its destination; experts consider under 10 milliseconds of latency to be critical for LED volumes displaying real-time content.

Lens mapping

The process of quantifying the distortion of a lens by shooting a lens chart and then analyzing it. Used for matching visual effects with real-world cinematography. See also camera calibration and alignment.

Marker

A physical reference for tracking purposes. See also active marker and passive marker.

Motion control (Moco)

A special rig which uses mechanical servos and computer control to create precise, repeatable movements for visual effects shots. Can be applied to camera rigs or to physical elements.

Outside-in tracking

A method of camera tracking which uses cameras or sensors mounted on the perimeter of a volume to analyze the position of the camera and other objects. See also inside-out tracking.

Passive marker

A physical reference for tracking purposes such as a retroreflective spheres. Fiducial passive markers are printed glyphs used for image-based tracking.

Simultaneous localization and mapping (SLAM)

A method of tracking which analyzes physical features of the real-world to compute position and translation in real-time.

Sputnik

Nickname for the tracking marker affixed to a motion picture camera for outside-in tracking within an LED volume. Also referred to as The Crown.

Tracking

The process of determining the position and orientation of a camera or other object relative to the scene via various optical/digital methods; used for integration between the virtual and physical worlds.

Waldo

A mechanical input device with encoders attached so that any motion of the device can be read by a computer as locations or rotations in 3D space. Waldos are used to assist in the animation of motion-controlled rigs for virtual environments and to puppet virtual characters.

Witness camera

Camera(s) placed on set to provide alternate perspectives on a shoot and provide a comprehensive understanding of the action within a scene. Often used to facilitate remote collaboration, or to capture additional data for later visual effects work.