Before revision: Derivation of invariant properties of geons Viewpoint invariance: The viewpoint invariance of geons derives from their being distinguished by three nonaccidental properties (NAPs) of contours that do not change with orientation in depth: Whether the contour is straight or curved, The vertex that is formed when two or three contours coterminate (that is, end together at the same point), in the image, i.e., an L (2 contours), fork (3 contours with all angles < 180°), or an arrow (3 contours, with one angle > 180°), and Whether a pair of contours is parallel or not (with allowance for perspective).
After revision: Something Shape LikeDerivation of invariant properties of geons Viewpoint invariance: The viewpoint invariance of geons derives from their being distinguished by three nonaccidental properties (NAPs) of contours that do not change with orientation in depth: Whether the contour is straight or curved, The vertex that is formed when two or three contours coterminate (that is, end together at the same point), in the image, i.e., an L (2 contours), fork (3 contours with all angles < 180°), or an arrow (3 contours, with one angle > 180°), and Whether a pair of contours is parallel or not (with allowance for perspective).