  Basic patterns are the source of a wide range of more or less complex
geometric structures. We will exploit such patterns to develop new efficient
visual markers. Besides being projective invariants, the proposed markers allow
producing rich panel of unique identifiers, highly required for
resource-intensive navigation and augmented reality applications. The spiral
topology of our markers permits the validation of an accurate identification
scheme, which is based on level set methods. The robustness of the markers
against acquisition and geometric distortions is validated by extensive
experimental tests.
