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Digital watermarking maps and signs, and related navigational tools

  • US 7,506,169 B2
  • Filed: 07/23/2007
  • Issued: 03/17/2009
  • Est. Priority Date: 03/05/2001
  • Status: Expired due to Term
First Claim
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1. An apparatus to read two or more digital watermarks embedded within a map, each of the two or more digital watermarks includes location information for a respective map location, the two or more digital watermarks are embedded through alterations to data representing the map, the alterations are generally imperceptible to a human observer of the map, said apparatus comprising:

  • a global positioning system receiver to determine a physical location of said apparatus;

    an input to receive data corresponding to at least a portion of the respective map location;

    a processor or electronic processing circuitry to extract location information from received data and to correlate the physical location with extracted location information; and

    an output to output an indication of a relative correlation between the physical location and watermark location information.

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