What is the difference between active and passive markers in motion capture?

• A. Active markers are retroreflective.
• B. Passive markers emit light using LEDs.
• C. Active markers use LEDs to emit light, while passive markers are retroreflective and reflect light emitted by the camera system.
• D. Active markers and passive markers are identical in how they operate.

Answer: (C)

In motion capture, the key difference is how light is handled. Active markers generate their own light signal, typically with LEDs, so the cameras see a bright, self-emitted beacon to track. Passive markers don’t emit light; they rely on retroreflective surfaces that reflect the light the cameras project back toward them, so tracking depends on that reflected signal. This is exactly captured by saying active markers emit light with LEDs, while passive markers are retroreflective and reflect light from the camera system. The other statements misstate the mechanism: one says active markers are retroreflective, another says passive markers emit light, and another claims they operate identically.