Why is infrared light preferred in camera-based motion capture systems?

• A. It reduces cost compared to visible light.
• B. It allows for markers that are easily distinguished from ambient light, improving tracking accuracy.
• C. It glows in the dark so markers are visible.
• D. It requires no sensors at all.

Answer: (B)

Using infrared light helps isolate marker signals from the surrounding lighting, making tracking more accurate. In camera-based systems, markers must be detected reliably across multiple synchronized cameras. Visible-room lighting can vary in intensity and color and create clutter that makes markers hard to distinguish. Illumination and sensing in the infrared range, with IR-pass filters on the cameras, suppresses much of that background and ambient noise, so markers appear with high contrast. Whether markers are passive and reflect IR or active and emit IR, the result is a cleaner, more consistent signal that improves the precision of 3D position reconstruction. Other options aren’t the main reason: cost isn’t the core benefit, infrared doesn’t inherently glow in the dark, and sensors are still needed to capture the markers.