1. A method for tracking a shape in an image, the method comprising using a processing system to perform operations comprising: analyzing the image and identifying at least one curved planar element, wherein analyzing the image and identifying the at least one curved planar element comprises extracting a plurality of contours from the image, discarding any contours that do not satisfy a threshold requirement, identifying, from at least one remaining extracted contour, at least one distinguished feature having a property that is geometric invariant under projective transformation, determining whether the at least one remaining extracted contour matches a contour from an earlier image frame, and recognizing the at least one remaining extracted contour associated with the at least one distinguished feature as the at least one curved planar element when the at least one remaining extracted contour matches the contour from the earlier image frame; determining a pose of an image capture device from the at least one curved planar element; determining a transformation for an augmented reality element associated with the at least one curved planar element based on the pose of the image capture device; and combining the augmented reality element with the image.