Using several clever hacking techniques, Niklas Roy can make thermal images using a “simple” thermometer.
True IR (infrared) cameras are still too expensive for many of us, but if you’d just like to know the temperature of something at a distance, IR thermometers aren’t that costly. In theory, if you were to take readings in a grid, color code them, and overlay these readings on an image, you would have a manual IR picture. If you can accomplish this manually, the obvious next step is, why can’t a computer?
Per Roy’s clever hack, yes, this is absolutely possible. His device uses a computer along with an Arduino and two servos to trace a grid with a thermometer. It reads the display at these different points using a webcam, then resolves everything into a nice picture. When overlaid with an actual image, it becomes a low (70 x 44 pixel) resolution thermal image.