Optically readable coded target

• US 5,260,556 A
• Filed: 06/18/1991
• Issued: 11/09/1993
• Est. Priority Date: 12/20/1988
• Status: Expired due to Fees

• Current Assignee: Australian Meat & Live-Stock Research & Development Corporation
• Original Assignee: Australian Meat & Live-Stock Research & Development Corporation
• Inventors: Moore, John C., Doerr, Annegret, Lake, Royden J., Kowald, Errol M.
• Primary Examiner(s): PITTS, HAROLD I
• Application Number:
  US07/690,994
• Time in Patent Office: 875 Days
• Field of Search: 235/464, 235/466, 235/494
• US Class Current: 235/494
• CPC Class Codes: A01K 11/001 Ear-tags
• CPC Class Codes: G06K 19/06037 multi-dimensional coding
• CPC Class Codes: G06K 19/06131 the marking comprising a target pattern, e.g. for indicating the center of the bar code or for helping a bar code reader to properly orient the scanner or to retrieve the bar code inside of an image
• CPC Class Codes: G06K 2019/06243 concentric-code
• CPC Class Codes: G06K 2019/06253 for a specific application
• CPC Class Codes: G06K 2019/06262 with target- or other orientation-indicating feature

Abstract

A target for providing coded data readable by an imaging apparatus. Location marking means enable location of the target by the imaging apparatus preparatory to an imaging operation, the location marking means having high visibility characteristics e.g. being of retroreflective material to enable identification of the location marking means against a background. Code marking regions of annular shape include circumferentially disposed code markings containing coded data which are imaged by the imaging apparatus to enable recovery of the coded data from the target. The location marking means is located generally centrally of the code marking regions so that identification of the location marking means also locates the center of the code marking regions. The location marking means includes at least one concentric annular region to enable fine location of the center. The code marking regions are rotationally dispersed relative to the center.

Claims

1. A target for providing coded data readable by an imaging apparatus, the target comprising:

location marking means for enabling location of said target by said imaging apparatus preparatory to an imaging operation carried out by said imaging apparatus;

said target further including at least two code marking regions, said location marking means being provided in a predetermined relationship to said at least two code marking regions;

each of said at least two code marking regions having a shape comprised by at least a segment of generally annular shape, and each of said at least two code marking regions including circumferentially disposed code markings containing coded data which are imaged by the imaging apparatus to enable recovery of the coded data from said target during or following said imaging operation, said at least two code marking regions sharing in common a center of curvature of said generally annular shapes and being spaced from said center of curvature at different radial distances; and

each of said at least two code marking regions containing the same coded data which is located at different rotational positions relative to said center of curvature so that the coded data is replicated in full at different radial distances from said center of curvature and at least two different rotationally dispersed locations thereby enabling attempted readings of the coded data by the imaging apparatus from at least two sets of replicated code markings.

2. A target as claimed in claim 1 wherein there are three of said code marking regions each of which contains the same coded data, said three code marking regions being arranged at three different radial distances from said center of curvature, the coded data in each of said three code marking regions being angularly displaced by 120°

relative to the other two of the code marking regions about said center of curvature so that the same coded data is replicated three times at equal angular intervals around said center of curvature.

3. A target for providing coded data readable by an imaging apparatus, the target comprising:

location marking means for enabling location of said target by said imaging apparatus preparatory to an imaging operation carried out by said imaging apparatus;

said target further including at least one code marking region, said at least one code marking region having a shape comprised by at least a segment of a generally annular shape, and said at least one code marking region including circumferentially disposed code markings containing coded data which are imaged by said imaging apparatus to enable recovery of the coded data from the target during or following the imaging operation;

said coded data being replicated in full at each of at least two different rotationally dispersed locations relative to the center of curvature of said generally annular shape thereby enabling attempted readings of the coded data by said imaging apparatus from at least two sets of replicated code markings, said location marking means having high visibility characteristics to enable identification of the location marking means by said imaging apparatus against a background; and

said location marking means including at least one annular region which is substantially concentric with said at least one code marking region to enable fine location by said imaging apparatus of the center of curvature of said at least one code marking region.

4. A target as claimed in claim 3 wherein said annular region comprises at least two rings, one ring of said two rings having high visibility characteristics and a further ring of said two rings having contrasting low visibility characteristics, the contrasting rings facilitating identification of the annular region during the location operation.

5. A target for providing coded data readable by an imaging apparatus, the target comprising:

location marking means for enabling location of said target by the imaging apparatus preparatory to an imaging operation carried out by said imaging apparatus;

said target further including at least one code marking region, said at least one code marking region having a shape comprised by at least a segment of a generally annular shape, and said at least one code marking region including circumferentially disposed code markings containing coded data which are imaged by said imaging apparatus to enable recovery of the coded data from said target during or following the imaging operation;

said coded data being replicated in full at each of at least two different rotationally dispersed locations relative to the center of curvature of said generally annular shape thereby enabling attempted readings of the coded data by said imaging apparatus from at least two sets of replicated code markings, said location marking means having high visibility characteristics to enable identification of said location marking means by said imaging apparatus against a background, said location marking means including at least one annular region which is substantially concentric with said at least one code marking region to enable fine location by said imaging apparatus of the center of said at least one code marking region; and

said annular region being located at a significant radial distance from the general center of curvature of said at least one code marking region so as to facilitate identification by said imaging apparatus of the annular region, said annular region not being located at an outer peripheral edge of the target where degradation of the annular region may interfere with the imaging operation.

6. A target as claimed in claim 5 wherein said annular region comprises at least two rings, one ring of said two rings having high visibility characteristics and a further ring of said two rings having contrasting low visibility characteristics, the contrasting rings facilitating identification of said annular region during the location operation.

7. A target for providing coded data readable by an imaging apparatus, the target comprising:

location marking means for enabling location of said target by said imaging apparatus preparatory to an imaging operation carried out by the imaging apparatus;

said target further including at least one code marking region, said at least one code marking region having a shape comprised by at least a segment of a generally annular shape, and said at least one code marking region including circumferentially disposed code markings containing coded data which are imaged by the imaging apparatus to enable recovery of said coded data from said target during or following said imaging operation, said coded data being replicated in full at each of at least two different rotationally dispersed locations relative to the center of curvature of said generally annular shape thereby enabling attempted readings of the coded data by said imaging apparatus from at least two sets of replicated code markings;

said location marking means including a central marking region located generally centrally of said at least one code marking region so that identification by said imaging apparatus of the central region of said location marking means locates the general position of the center of curvature of said at least one code marking region; and

said location marking means further including at least one annular marking region radially spaced from and substantially concentric with said central marking region of the location marking means, and the identification of the annular marking region enabling fine location by the imaging apparatus of the center of curvature of said at least one code marking region.

8. A target as claimed in claim 7 wherein said annular region comprises at least two rings, one ring of said two rings having high visibility characteristics and a further ring of said two rings having contrasting low visibility characteristics, the contrasting rings facilitating identification of said annular region during the location operation.

9. A target as claimed in claim 7 wherein said annular region is located at a significant radial distance from the general center of said at least one code marking region so as to facilitate identification of said annular region, but not being located at the edge of said target where degradation of said annular region may interfere with the imaging operation.

16. A target as claimed in claim 8 wherein said annular region is located at a significant radial distance from the general center of said at least one code marking region so as to facilitate identification of the annular region, but not being located at the edge of the target where degradation of the annular region may interfere with the imaging operation.

10. An optically readable coded data retrieval system comprising a target for providing coded data and an imaging apparatus for identifying the target and recovering the coded data from the target, the imaging apparatus including:

a radiation source operative to direct radiation generally towards said target;

said target comprising location marking means for enabling location of said target by said imaging apparatus preparatory to an imaging operation carried out by said imaging apparatus;

said target further including at least one code marking region, said at least one code marking region having a shape comprised by at least a segment of a generally annular shape, said at least one code marking region including circumferentially disposed code markings containing coded data which are imaged by said imaging apparatus to enable recovery of the coded data from the target during or following the imaging operation, and the coded data being replicated in full at each of at least two different rotationally dispersed locations relative to the center of curvature of said generally annular shape thereby enabling attempted readings of the coded data by said imaging apparatus from at least two sets of replicated code markings; and

said location marking means comprising a retro-reflective material so that radiation from the radiation source of the imaging apparatus which is directed towards the target is strongly reflected back to said imaging apparatus, said imaging apparatus being operative to identify said location marking means and recover the coded data from said at least one code marking region.

11. A target as claimed in claim 10 wherein said location marking means is located generally centrally of said at least one code marking region so that identification of the location marking means also enables the general location of the center of said at least one code marking region.

12. A target as claimed in claim 10 wherein said location marking means includes at least one annular region which is substantially concentric with said at least one code marking region to enable fine location by the imaging apparatus of the general center of said at least one code marking region.

13. A system as claimed in claim 10 wherein said code markings are comprised by visibly contrasting regions so as to represent respectively a binary "0" and "1", said retro-reflective material forming a substrate of said target and the code markings being operative to substantially prevent radiation reflection from the retro-reflective material of said substrate or to permit radiation reflection from said radiation source back to the imaging apparatus.

15. A system as claimed in claim 10 wherein said imaging apparatus includes a position sensing and tracking means which includes a wide angle imaging system and is operative to locate and generally center said target within the wide field of view of the wide angle imaging system, said imaging apparatus further including an image recording device having a narrow field of view in which said target is located when centered within said wide field of view and which is operative to capture a focused image of the target for use in recovering the coded data from said target.

17. A target as claimed in claim 11 wherein said location marking means includes at least one annular region which is substantially concentric with said at least one code marking region to enable fine location by the imaging apparatus of the general center of said at least one code marking region.

18. A system as claimed in claim 17 wherein said code markings are comprised by visibly contrasting regions so as to represent respectively a binary "0" and "1", said retro-reflective material forming a substrate of said target and the code markings being operative to substantially prevent radiation reflection from the retro-reflective material of the substrate or to permit radiation reflection from the radiation source back to the imaging apparatus.

19. A system as claimed in claim 11 wherein said code markings are comprised by visibly contrasting regions so as to represent respectively a binary "0" and "1", said retro-reflective material forming a substrate of said target and the code markings being operative to substantially prevent radiation reflection from the retro-reflective material of said substrate or to permit radiation reflection from said radiation source back to the imaging apparatus.

14. An optically readable coded data retrieval system comprising:

a target for providing coded data and an imaging apparatus for identifying said target and recovering the coded data from said target;

said imaging apparatus including a radiation source operative to direct radiation generally towards the target;

said target comprising location marking means for enabling location of the target by said imaging apparatus preparatory to an imaging operation carried out by said imaging apparatus, said target further including at least two code marking regions;

each of said at least two code marking regions having a shape comprised by at least a segment of a generally annular shape, each of said at least two code marking regions including circumferentially disposed code markings containing coded data which are imaged by the imaging apparatus to enable recovery of the coded data from the target during or following said imaging operation, said at least two code marking regions sharing in common a center of curvature of said generally annular shapes and being spaced from said center of curvature at different radial distances, and each of said at least two code marking regions containing the same coded data and being located at different rotational positions relative to the center of curvature so that the coded data is replicated in full at different radial distances from the center of curvature and at least two different rotationally dispersed locations thereby enabling attempted readings of the coded data by said imaging apparatus from at least two sets of replicated code markings;

said location marking means comprising a retro-reflective material so that radiation from said radiation source of said imaging apparatus which is directed towards said target is strongly reflected back to said imaging apparatus; and

said imaging apparatus being operative to identify the location marking means and recover the coded data from said at least one code marking region.