US 8,015,227 B2 · Method in creating a symbol pattern, symbol pattern obtained thereby, method and system for finding a position in such symbol pattern and computer program product for performing the method

Abstract

The invention relates to a method in creating a two-dimensional symbol pattern which may be utilized to determine a position in a large area covered by the pattern, for example for recording handwritten information by means of a pen-like instrument. The invention is useful for creating a symbol pattern having desired properties, namely that any sufficiently large observed part of the pattern is unique, enabling an unambiguous determination of position. The symbol pattern is based on a non-repeating sequence of symbol values Sk that each corresponds to a fixed linear combination of the coefficients of the monomials in xk mod P(x), where P(x) is any polynomial of degree n in the field Fq. The symbol pattern is generated by folding the sequence according to a wrapping scheme. The invention also relates to methods and systems for finding the position of a group of observed symbol values in this symbol pattern and computer program products performing the methods.

Claims40

Dependent claims

A computer-implemented method in creating a two-dimensional symbol pattern PW having the property that any subset of symbol values observed in the symbol pattern and having the size m is unique, comprising:

generating, by using a processor, a non-repeating sequence S of symbol values Sk that each corresponds to a fixed linear combination of coefficients C of monomials in xk mod P(x), where P(x) is any polynomial of degree n in field Fq;
generating, by using the processor, a mask vector B comprising m symbol values based on a mask pattern with a defined shape;
storing, in a memory device, the mask vector B;
and
defining, by using the processor, a wrapping scheme W for folding the sequence into said two-dimensional symbol pattern PW, wherein said polynomial P(x), said mask pattern, and said wrapping scheme W are defined such that a transform matrix T that fulfils the matrix equation B=TC has a rank N=n over Fq.

2 more elements

A computer-implemented method of finding a position (X,Y) of a mask B observed in a two-dimensional symbol pattern PW having the property that any mask B with a defined shape and a size of at least m symbol values is unique, the symbol pattern being based on a non-repeating sequence S of symbol values Sk that each corresponds to a fixed linear combination of coefficients C of monomials in xk mod P(x), where P(x) is any polynomial of degree n in field Fq, and the symbol pattern PW being formed by folding said sequence S according to a wrapping scheme W, said method comprising:

retrieving, from a memory device, information about a relationship between the symbol values in the mask B and the corresponding coefficients C;
extracting, by using a processor, the symbol values of said mask B at said position (X,Y);
calculating, by using the processor, the corresponding coefficients CX,Y from BX,Y by means of said relationship, where BX,Y are the extracted symbol values of B at said position (X,Y);
determining, by using the processor, a location k in the sequence S where the coefficients C equal CX,Y;
and
calculating, by using the processor, said position (X,Y) in the symbol pattern PW based on the location k and the wrapping scheme W.

3 more elements

A computer-implemented method of calculating a symbol value Sk in a non-repeating sequence S of symbol values that each corresponds to a fixed linear combination G of coefficients C of monomials in xk mod P(x), where P(x) is any polynomial of degree n in field Fq, comprising:

calculating, by using a processor, rk≡xk(mod P(x)) by repeated squaring;
deriving, by using the processor, the symbol value Sk from G(rk);
and
storing, in a memory device, the symbol value Sk.

1 more element

A system for finding a position (X,Y) of a mask B observed in a two-dimensional symbol pattern PW having the property that any mask B with a defined shape and a size of at least m symbol values is unique, the symbol pattern being based on a non-repeating sequence S of symbol values Sk that each corresponds to a fixed linear combination of coefficients C of monomials in xk mod P(x), where P(x) is any polynomial of degree n in field Fq, and the symbol pattern PW being formed by folding said sequence S according to a wrapping scheme W, said system comprising:

a memory device for storing information about a relationship between the symbol values in B and the corresponding coefficients C;
and
a processor for:
extracting, from the memory device, the symbol values of said mask B at said position (X,Y);
calculating the corresponding coefficients CX,Y from BX,Y based on said relationship, where BX,Y are the extracted symbol values of B at said position (X,Y);
calculating the location k in the sequence S where the coefficients C equal CX,Y;
and
calculating said position (X,Y) in the symbol pattern PW based on the location k and the wrapping scheme W.

5 more elements

Dependencies are inferred from the claim text.

Method in creating a symbol pattern, symbol pattern obtained thereby, method and system for finding a position in such symbol pattern and computer program product for performing the method

Life of this patent

Method in creating a symbol pattern, symbol pattern obtained thereby, method and system for finding a position in such symbol pattern and computer program product for performing the method

Life of this patent

Abstract

Claims40