A system for digitally overlaying an image with another image is disclosed. A storage is for storing a model of a real world space, wherein the model includes an overlay surface to be overlaid with an overlay image. A camera parameter interface is for receiving camera parameters. A camera image interface is for receiving at least one image. A positioner is for determining a position of the overlay surface within the at least one captured image based on the model and the camera parameters. A detector is for detecting an occluding object based on an image property of the occluding object and a detection image. An overlayer is for overlaying a non-occluded portion of the overlay surface in the selected captured image with the overlay image to obtain an output image.