1. A computer-implemented method comprising: capturing images from a moving mobile camera; identifying a first stationary feature that is present in the images captured from the moving mobile camera; identifying a second stationary feature that is present in the images captured from the moving mobile camera, the second stationary feature being different than and spaced apart from the first stationary feature; determining a description of motion of the moving mobile camera in a depth direction based on changes in distance between the first stationary feature and the second stationary feature within the captured images, the depth direction being a direction of movement toward and away from the first stationary feature and the second stationary feature; rendering a user interface for an application on an interface device, the user interface including an object; and automatically controlling movement of the object rendered in the user interface in a manner corresponding to the determined motion of the moving mobile camera in the depth direction.