Method of sensing symmetric coded tags

• US 7,982,929 B2
• Filed: 05/31/2009
• Issued: 07/19/2011
• Est. Priority Date: 03/04/2003
• Status: Expired due to Fees

• Current Assignee: Silverbrook Research Pty Limited
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia, Lapstun, Paul
• Primary Examiner(s): Haskins; Twyler L
• Assistant Examiner(s): Chen; Huo Long
• Application Number:
  US12/475,561
• Publication Number:
  US 20090236423A1
• Time in Patent Office: 779 Days
• Field of Search: None
• US Class Current: 358/539
• CPC Class Codes: G06K 19/06037 multi-dimensional coding

Abstract

A method of using a sensing device to read coded data is provided. The coded data is arranged in accordance with a layout having mirror and n-fold rotational symmetry about a center of rotation, where n is at least two. The layout includes n identical first sub-layouts rotated 1/n revolutions apart about the center of rotation, and n identical second sub-layouts rotated 1/n revolutions apart about the center of rotation. Each second sub-layout is a reflection of a corresponding one of the first sub-layouts. At least one sub-layout includes rotation-indicating data that distinguishes that sub-layout from at least one other sub-layout and reflection-indicating data that distinguishes the reflections of reflected sub-layouts. The method includes sensing a layout using the sensing device, decoding the coded data of the sensed sub-layouts, thereby determining the rotation-indicating data of that sub-layout, and using the rotation-indicating data to interpret the meaning of the coded data.

Claims

1. A method of using a sensing device to read machine-readable coded data, the coded data being arranged in accordance with at least one layout having n-fold rotational symmetry about a center of rotation, where n is at least two, and having mirror symmetry, the layout including:

n identical first sub-layouts rotated 1/n revolutions apart about the center of rotation, and,

n identical second sub-layouts rotated 1/n revolutions apart about the center of rotation, each second sub-layout being a reflection of a corresponding one of the first sub-layouts, at least one sub-layout including;

rotation-indicating data that distinguishes that sub-layout from at least one other sub-layout; and

reflection-indicating data that distinguishes the reflection of that sub-layout from the reflection of a corresponding reflected sub-layout, the method comprising the steps of;

sensing at least one layout using the sensing device;

decoding the coded data of at least one of the sub-layouts of the sensed layout, thereby determining at least the rotation-indicating data of that sub-layout; and

using the rotation-indicating data to interpret the meaning of at least some of the coded data.

2. A method according to claim 1, each layout including at least one target feature representing at least a position and a rotation of the layout, the method of reading the coded data including:

imaging the surface to generate an image thereof,

processing the image to locate one or more target features; and

on the basis of the located target features, determining at least one of the position and the rotation of at least one of the sub-layouts.

3. A method according to claim 1, each layout including a codeword, the codeword being encoded in each sub-layout, the method including decoding the codeword from at least one of the sub-layouts.

4. A method according to claim 1, at least one sub-layout including type-indicating data, the method including:

determining at least the type-indicating data of the at least one sub-layout; and

,

using the type-indicating data to interpret the meaning of at least some of the coded data.