https://www.scientificamerican.com/article/a-shiny-snack-bags-reflections-can-reconstruct-the-room-around-it/

Still-life artists know that to make an image of an object look like the real thing, they must account for the way light reflects off it. The appearance of these glimmers—their color, position and brightness—is influenced by the item’s surroundings. And this effect means an object can, in turn, reveal key aspects of its environment. Researchers have now found that by filming a brief video clip of a shiny item, they can use the light flashing off it to construct a rough picture of the room around it. The results are surprisingly accurate, whether the reflections come from a bowl, a cylinder or a crinkly bag of potato chips.

The mathematical model used to reconstruct environments can also approximate what a known object will look like—how light will reflect off it—when it is placed in new surroundings or is seen from a new angle. These two applications are linked. “The challenge of our research area is that everything so entangled,” says Jeong Joon Park, a Ph.D. student at the University of Washington’s Graphics and Imaging Laboratory (GRAIL). “You need to solve for lighting to get the good appearance. You need to have a good appearance model to get the good lighting. The answer might be to solve them all together—like we did.”