Seeing is the conversion of light to meaning. Light reflected from surfaces, arriving at the eyes or the imaging plane of a camera, must be interpreted to be useful to an organism or robot. This interpretation is a process of inference from ambiguous and incomplete measurements using experience and knowledge. The Perceiving Systems Department is focused on uncovering the fundamental mathematical and computational principles underlying this process. This means understanding the statistics of the world (its shape, motion, material properties, etc.), modeling the imaging process (including optical blur, motion blur, noise, discretization), and devising algorithms to convert light measurements into information about the structure of the world.