A method for retrieving information encoded in a structured illumination pattern including selecting an encoded structured illumination pattern having a variable intensity; providing an object with a surface having a 3D relief pattern; selecting at least one portion but not all of the object's surface including the 3D surface relief pattern; projecting the selected structured illumination pattern onto the selected portion of the surface; using a digital camera to capture an image of the reflected structured light pattern from the selected portion of the surface; storing the image in a memory; and processing the image of the detected reflected structured light pattern using a processor responsive to the detected reflected structured light pattern and the selected structured light pattern to retrieve the encoded information, wherein the encoded information is based on the geometrical and material properties of the 3D surface relief pattern and is distinct from the object, surface, or relief pattern.