Objects and their placement within a particular scene may be characterized using structured light with no or minimal manual intervention or calibration to the scene. The structured light pattern may be rendered with visible light, yet imperceptible to users, by generating a set of opposing excursions in one or more image properties for durations which are shorter than the integration time of the human eye. A set of assumptions and ongoing testing of those assumptions against physical objects identified within the environment allows characterization of the scene and the objects therein.