Uncanny Atlas
Tool

Structured light sensor (SLS) camera

A repurposed Xbox Kinect that ghost hunters connect to a screen to look for human shapes where nobody is standing.

What users say it does
Ghost hunters say it can show spirits as stick figures on the monitor, according to Kenny Biddle in Skeptical Inquirer and the McGill Office for Science and Society. Biddle adds that believers took to it because it works with infrared light, which many of them think can reveal ghosts.
What it measures
Wikipedia explains that the original Kinect projects a pattern of near-infrared dots, reads how objects bend that pattern with an infrared sensor, and works out depth from it. A 2011 Microsoft Research paper by Shotton and colleagues describes software that estimates where a body's joints are from one depth image.

Microsoft built the Kinect as a motion sensor so video game players could control a game with their bodies instead of a handheld controller, McGill's Office for Science and Society explains. Kenny Biddle, writing in Skeptical Inquirer in 2017, says Paranormal Activity 4, a film released in October 2012, is what first led ghost hunters to think a Kinect might see spirits. He says the belief rested on fiction and on the device's likeness to the laser grid, or Shadow Detector, already in their kits.

McGill notes that the sensor was never designed for rooms full of furniture and equipment, and that it can mistake one end of a couch for a body and draw a stick figure there. In a 2022 Skeptical Inquirer episode, Biddle took up a challenge from a YouTuber who said his house was very haunted and that the Kinect showed stick figures walking around it.

Sources