Coding pattern comprising orientation codes

Abstract

A substrate having a coding pattern disposed on a surface thereof. The coding pattern has target elements defining cells, and a set of data elements contained in each cell encoding tag data. The tag data of each cell encodes first and second orthogonal registration symbols. The first and second orthogonal registration symbols together identify an orientation of a layout of the tag data with respect to the target grid. The first registration symbol identifies a first direction component of the orientation, and the second registration symbol identifies a second direction component of the orientation.

1 . A substrate having a coding pattern disposed on a surface thereof, said coding pattern comprising:
 a plurality of target elements defining cells; and   a set of data elements contained in each cell encoding tag data, wherein the tag data of each cell encodes first and second orthogonal registration symbols, the first and second orthogonal registration symbols together identifying an orientation of a layout of said tag data with respect to said target grid, said first registration symbol identifying a first direction component of said orientation, and said second registration symbol identifying a second direction component of said orientation.   
     
     
         2 . The substrate of  claim 1 ,wherein neighboring cells share target elements; 
     
     
         3 . The substrate of  claim 1 , wherein said set of data elements is represented by multi-pulse position modulation. 
     
     
         4 . The substrate of  claim 3 , wherein said set of data elements consists of m macrodots, each of said macrodots occupying a respective position from a plurality of predetermined possible positions p within said cell, the respective positions of said macrodots representing one of a plurality of possible registration symbol values for said registration symbols. 
     
     
         5 . The substrate of  claim 4 , wherein m is 2 or more and p>m. 
     
     
         6 . The substrate of  claim 4 , wherein m is 2 and p is 6 so as to provide 15 possible registration symbol values. 
     
     
         7 . The substrate of  claim 4 , wherein a plurality of said registration symbol values are mapped to a direction code symbol value, said direction code symbol value representing a direction component of said orientation. 
     
     
         8 . The substrate of  claim 7 , wherein said orientation is one of four possible orientations, said orientation being identifiable via a pair of 1-bit direction code symbol values. 
     
     
         9 . The substrate of  claim 8 , wherein said each registration symbol value read in a first orientation is reversed when read in an opposite second orientation. 
     
     
         10 . The substrate of  claim 9 , wherein each registration symbol value maps to a “0” direction code symbol value when read in said first orientation, and maps to a “1” direction code symbol value when read in said second orientation, such that determination of the orientation of said tag data is independent of an orientation in which said registration symbol is read. 
     
     
         11 . The substrate of  claim 4 , wherein each registration symbol further identifies at least one of:
 a translation of said cell relative to a tag containing said cell; and   a flag.   
     
     
         12 . The substrate of  claim 11 , wherein each registration symbol value maps to an identical flag code symbol value irrespective of an orientation of reading said registration symbol.