Editing Motion capture (section)

===Active marker===
[[File:Body Motion Capture.jpg|thumb|Body motion capture]]
Active optical systems triangulate positions by illuminating one LED at a time very quickly or multiple LEDs with software to identify them by their relative positions, somewhat akin to celestial navigation. Rather than reflecting light back that is generated externally, the markers themselves are powered to emit their own light. Since the inverse square law provides one quarter of the power at two times the distance, this can increase the distances and volume for capture. This also enables a high signal-to-noise ratio, resulting in very low marker jitter and a resulting high measurement resolution (often down to 0.1&nbsp;mm within the calibrated volume).

The TV series ''[[Stargate SG1]]'' produced episodes using an active optical system for the VFX allowing the actor to walk around props that would make motion capture difficult for other non-active optical systems.{{citation needed|date=August 2016}}

ILM used active markers in ''[[Van Helsing (film)|Van Helsing]]'' to allow capture of Dracula's flying brides on very large sets similar to Weta's use of active markers in ''[[Rise of the Planet of the Apes]]''. The power to each marker can be provided sequentially in phase with the capture system providing a unique identification of each marker for a given capture frame at a cost to the resultant frame rate. The ability to identify each marker in this manner is useful in real-time applications. The alternative method of identifying markers is to do it algorithmically requiring extra processing of the data.

There are also possibilities to find the position by using colored LED markers. In these systems, each color is assigned to a specific point of the body.

One of the earliest active marker systems in the 1980s was a hybrid passive-active mocap system with rotating mirrors and colored glass reflective markers and which used masked linear array detectors.