In one embodiment, a method includes accessing a digital image captured by a camera that is connected to a machine-detectable object, detecting a reflection of the machine-detectable object in the digital image, computing, in response to the detection, a plane that is coincident with a reflective surface associated with the reflection, determining a boundary of the reflective surface in the plane based on at least one of a plurality of cues, and storing information associated with the reflective surface, where the information includes a pose of the reflective surface and the boundary of the reflective surface in a 3D model of a physical environment, and where the information associated with the reflective surface and the 3D model are configured to be used to render a reconstruction of the physical environment.