1. A method comprising: capturing, using a video capture device, a video stream that includes an activity scene of a physical activity surface and one or more interface objects physically interactable with by a user; processing, using one or more computing devices, the activity scene of the physical activity surface in the video stream for motion for a predetermined period of time; detecting, using the one or more computing devices, motion in the activity scene based on the processing; responsive to detecting the motion, processing, using the one or more computing devices, the video stream to detect one or more interface objects included in the activity scene of the physical activity surface; and presenting virtual information on a computer display based on the one or more detected interface objects.