US 2006/0136532 A1 · Light reflection intensity calculation circuit

Abstract

A circuit for calculating a light reflected component with high accuracy. The circuit for calculating a reflected component of light reflected from an object having a rough surface comprises a means for storing the reflectance of an object in relation to the value φ or the value of cos φ, letting a surface normal vector be denoted by a vector N, a light source incidence unit vector be denoted by a vector L, a line-of-sight unit vector be denoted by V, a half vector of the light source incidence vector L and the line-of-sight vector V be denoted by H and defining the inner products as N·L=cos θ, N·V=cos γ, V·H=cos φ, N·H=cos β; a means for storing a luminance distribution in relation to the value of β or the value of cos β; a means for acquiring information on the reflectance term (Fλ(φ)) of the reflected component according to the value of φ or the value of cos φ from the reflectance storing means; a means for acquiring information on the luminance distribution term (D′(β)) of the reflected component according to the value of β or the value of cos β from the luminance distribution storing means; a means for acquiring information on max[0.5 cos θ cos φ, 0.5 cos φ cos γ, cos θ cos β cos γ] which is the maximum value out of 0.5 cos θ cos φ, 0.5 cos φ cos γ, cos θ cos β cos γ; a means for determining the reciprocal of the max[0.5 cos θ cos φ, 0.5 cos φ cos γ, cos θ cos β cos γ] and acquiring information on the geometrical attenuation factor term G′(β,θ,γ,φ) of the reflected component; and a means for acquiring information on the reflected component from the information on the luminance distribution term (D′(β)) and information on the geometrical attenuation factor term G′(β,θ,γ,φ).

Claims14

Dependent claims

A circuit to compute a reflection intensity on rough surface, defining:

surface normal vector as N, light-source incidence vector as L, view direction vector as V, half-vector between L and V as H, N·L=cos θ, N·V=cos γ, V·H=cos φ, and N·H=cos θ, comprising:
a means for storing a reflectance as a function of φ or cos φ;
a means for storing a reflection distribution term as a function of β or cos β;
a means for obtaining a reflectance term (Fλ(φ)) from the means for storing reflectance using φ or cos φ as an index;
a means for obtaining a distribution function (D′(β)) from the means for storing a reflection distribution term using β or cos β as an index;
a means for obtaining the value of max[0.5 cos θ cos φ, 0.5 cos φ cos γ, cos φ cos β cos γ], which is a maximum value among 0.5 cos θ cos φ, 0.5 cos φ cos γ and cos θ cos β cos γ;
a means for obtaining a geometrical attenuation factor (G′(β,θ,γ,φ)) of the reflected component by computing a reciprocal of the max[0.5 cos θ cos φ, 0.5 cos φ cos γ, cos θ cos β cos γ];
and
a means for obtaining a reflection intensity using the terms of reflectance (Fλ(φ)), reflection distribution function (D′(β)) and geometrical attenuation factor (G′(β,θ,γ,φ)).

6 more elements

A circuit that computes a reflection intensity for calculating a reflection intensity of computer graphics images, defining the object surface by a set of polygons that have both or either microscopic grooves or partial areas of different reflectance, comprising:

a means for obtaining a surface normal vector N at every polygon vertex;
a means for obtaining a light-source incidence L at every polygon vertex;
a means for obtaining a view vector V at every polygon vertex a means for obtaining a texture mapping address (U,V) at every polygon vertex;
a means for interpolating the values of said surface normal vector N, said light-source incidence vector L, said view vector V and said texture mapping address (U,V) on polygon interior;
a means for reading a surface tangent vector Ti using the interpolated texture mapping address, from memory that stores the surface tangent vector Ti that is addressed by interpolated texture mapping address;
and
a means for computing a light-reflection intensity at each interpolated point of polygon interior using interpolated value of surface tangent Ti, interpolated value of surface normal vector Ni, interpolated value of light-source incidence vector Li and interpolated value of view vector Vi.

4 more elements

A compound anisotropic circuit, relating a computer graphics circuit for expressing light reflectance on an object surface including microscopic grooves and various reflectances, defining the object surface by a set of polygons, and defining surface normal, light-source incidence vector, view vector and texture mapping address at each polygon vertex, comprising:

a means for defining a surface tangent vector that indicates the direction of a groove on every interior point, storing the surface tangent of a two-dimensional array into memory;
and
a means for interpolating the surface normal vector, light-source incidence vector, view vector and texture mapping address, reading surface tangent from the memory assigned with texture mapping address, and computing a light reflection intensity by using the surface tangent vector, interpolated surface tangent vector, interpolated light-source incidence vector and interpolated view vector.

Dependencies are inferred from the claim text.

Light reflection intensity calculation circuit

Life of this patent

Light reflection intensity calculation circuit

Life of this patent

Abstract

Claims14