Reflectance estimating method
AssigneeToyota Jidosha Kabushiki Kaisha
InventorAtsushi Takagi
Life of this patent
Estimating the term…
Abstract
At first, a sample for obtaining light measurement data is set to obtain reflectances. After setting an arbitrary wavelength λI, a principal component analysis is executed to obtain an eigenvalue 1 and an eigenvector b. Then a basic equation for reflectance is determined by deriving a coefficient k, utilizing a known reflectance of an object of which reflectance is to be estimated. Thereafter a process of deriving a reflectance at an arbitrary displacement angle is executed for all the wavelengths, for example over a visible wavelength range. In this manner, the reflectance of an object at an arbitrary displacement angle can easily be obtained by utilizing the basic equation for the reflectance derived from the eigenvector obtained from the principal component analysis of the measured data.
Claims20
A reflectance estimating method for estimating a reflectance at an arbitrary displacement angle which is an angle representing displacement from a normal light reflecting direction of an object, the method comprising:
- (a) a step of executing a principal component analysis on reflectances at predetermined plural displacement angles;
- (b) a step of selecting a principal component vector obtained by the analysis as an eigenvector ;
- and
- (c) a step of estimating a reflectance at a displacement angle other than said predetermined displacement angles, at least based on said eigenvector.
A reflectance estimating method for estimating a reflectance at an arbitrary displacement angle which is an angle representing displacement from a normal light reflecting direction of an object, the method comprising:
- (a) a step of executing a principal component analysis on reflectances of predetermined plural displacement angles within a predetermined angular range;
- (b) a step of selecting a principal component vector and a principal component obtained by said principal component analysis respectively as an eigenvector and an eigenvalue, and determining characteristics of the eigenvector on the relationship between the eigenvalue and the displacement angle;
- (c) a step of determining a representative displacement angle from the determined characteristics;
- (d) a step of predetermining a basic equation on said reflectance, represented by said eigenvalue, said eigenvector and a coefficient to be multiplied on said eigenvector;
- (e) a step of determining said coefficient based on said basic equation, said representative displacement angle and a reflectance at said representative displacement angle and defining the basic equation utilizing the determined coefficient and said eigenvector as a calculation equation;
- (f) a step of estimating a reflectance at a displacement angle other than said predetermined displacement angles within said predetermined angular range, based on said calculation equation;
- and
- (g) a step of estimating a reflectance of a displacement angle outside said predetermined angular range by extrapolating said eigenvector.
A reflectance estimating method for estimating a reflectance (ρ) at an arbitrary displacement angle (α) which is an angle representing displacement from a normal light reflecting direction of an object, the method comprising:
- (1) a step of representing a reflectance (ρ) at an arbitrary displacement angle by a predetermined basic equation including an average value vector (μ), an eigenvector (b) and a coefficient k;
- (2) a step of setting an arbitrary wavelength (λi);
- (3) a step of executing a principal component analysis, at said arbitrary wavelength, on reflectances at predetermined plural displacement angles, thereby obtaining the eigenvector b and the average value vector μ corresponding to each of the reflectances;
- (4) a step of deriving a coefficient k utilizing a result obtained in said step (3) and the known reflectance of the object of which reflectance is to be estimated;
- and
- (5) a step of estimating a reflectance at a displacement angle other than said predetermined displacement-angles, based on said basic equation employing said derived coefficient k.
A reflectance estimating apparatus for estimating a reflectance at an arbitrary displacement angle which is an angle representing displacement from a normal light reflecting direction of an object, the apparatus comprising:
- means for executing a principal component analysis on reflectances at predetermined plural displacement angles;
- means for selecting a principal component vector obtained by the analysis as an eigenvector ;
- and
- means for estimating a reflectance at a displacement angle other than said predetermined displacement angles, at least based on said eigenvector.
A reflectance estimating apparatus for estimating a reflectance (ρ) at an arbitrary displacement angle (α) which is an angle representing displacement from a normal light reflecting direction of an object, the apparatus comprising:
- means for representing a reflectance (ρ) at an arbitrary displacement angle by a predetermined basic equation including an average value vector (μ), an eigenvector (b) and a coefficient k;
- means for setting an arbitrary wavelength (λi);
- means for executing a principal component analysis, at said arbitrary wavelength, on reflectances at predetermined plural displacement angles, thereby obtaining the eigenvector b and the average value vector μ corresponding to each of the reflectances;
- means for deriving a coefficient k utilizing a result obtained by the means for executing a principal component analysis and the known reflectance of the object of which reflectance is to be estimated;
- and
- means for estimating a reflectance at a displacement angle other than said predetermined displacement angles, based on said basic equation employing said derived coefficient k.
A reflectance estimating apparatus for estimating a reflectance at an arbitrary displacement angle which is an angle representing displacement from a normal light reflecting direction of an object, the apparatus comprising:
- a first memory for memorizing inputted reflectances at predetermined plural displacement angles;
- a second memory for memorizing, as an eigenvector, a principal component vector obtained as a result of a principal component analysis on the reflectances memorized in the first memory;
- a calculation means for estimating a reflectance at a displacement angle other than said predetermined displacement angles, at least based on said eigenvector memorized in the second memory.
A reflectance estimating apparatus for estimating a reflectance (ρ) at an arbitrary displacement angle (α) which is an angle representing displacement from a normal light reflecting direction of an object, the apparatus comprising:
- a first memory means for memorizing a predetermined basic equation which represents a reflectance (ρ) at an arbitrary displacement angle, the basic equation including an average value vector (μ), an eigenvector (b) and a coefficient k;
- a second memory for memorizing specific eigenvector b and average value vector μ obtained as a result of a principal component analysis, at an arbitrary wavelength (λi), on reflectances at predetermined plural displacement angles;
- means for deriving a coefficient k of the basic equation memorized in the first memory, based on the basic equation memorized in the first memory, the specific eigenvector b and average value vector μ memorized in the second memory, and the known reflectance of the object of which reflectance is to be estimated;
- a third memory for memorizing the basic equation including the derived coefficient k;
- means for estimating a reflectance at a displacement angle other than said predetermined displacement angles, based on the basic equation memorized in the third memory.
A recording medium which is readable by a computer, compring:
- a first data, given that a displacement angle represents displacement from a normal light reflecting direction of an object, including reflectances of the object measured at predetermined plural displacement angles;
- a second data including a principal component vector obtained as a result of a principal component analysis on the reflectances included in the first data;
- a program for selecting, as an eigenvector, the principal component vector included in the second data and estimating a reflectance at a displacement angle other than said predetermined displacement angles, at least based on said eigenvector.
Dependencies are inferred from the claim text.