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US5949424A
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Method, system, and computer program product for bump mapping in tangent space
Assignee: Microsoft Technology Licensing LLC
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Filing: 1997-02-28
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Granted: 1999-09-07
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Expires: 2017-02-28
Abstract
Abstract A method, system, and computer program product for accelerated shading of an object surface by bump mapping in tangent space. A tangent space transform module builds a tangent space transform matrix M(p) having elements comprised of normal, tangent, and binormal vector components determined at a surface point on the object surface. The tangent space transform module further transforms shading vectors, such as, lighting and viewing vectors, into a tangent space defined by the tangent space transform matrix and outputs corresponding tangent space shading vectors. A bump mapping module performs vector operations between one or more tangent space shading vectors and a perturbed normal N' in tangent space. A texture memory stores a surface dependent or a surface independent tangent space perturbed normal texture map. The lighting module computes a shading value for the surface point based on the vector operations. The shading value can be then be mapped to a pixel to shade the object surface rendered on a computer graphics display. The bump mapping module outputs diffuse and specular components. The diffuse component corresponds to a first dot product between a normalized, interpolated tangent space lighting vector and three perturbed normal components Nx', Ny', and Nz'. The specular component corresponds to a second dot product between a normalized, interpolated tangent space half angle vector and three perturbed normal components Nx', Ny', and Nz'. Different types of shading vectors and lighting equations can be used depending upon the chosen illumination model.
Inventors
- 👤 Brian Keith Cabral
- 👤 Mark Stuart Peercy
- 👤 John Milligan Airey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:21
CPC Classifications
G; G06; G06T; G06T15/00; G06T15/50; G06T15/60
Claims Analysis
Total Claims: 54
Claim 1
Independent Claim
128 words
A method for shading a computer graphics image, the computer graphics image including an object surface, comprising the steps of: building a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; transforming a shading vector at said point into a tangent space defined by said tangent space transform matrix to form a corresponding tangent space shading vector; performing a vector operation between said tangent space shading vector and a perturbed normal in tangent space at said point; and computing a shading value for said point based on said vector operation performed in said performing step; whereby, said shading value can be mapped to a pixel to shade the object surface.
Claim 2
Independent Claim
128 words
A method for shading a computer graphics image, the computer graphics image including an object surface, comprising the steps of: building a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; transforming a shading vector at said point into a tangent space defined by said tangent space transform matrix to form a corresponding tangent space shading vector; performing a vector operation between said tangent space shading vector and a perturbed normal in tangent space at said point; and computing a shading value for said point based on said vector operation performed in said performing step; whereby, said shading value can be mapped to a pixel to shade the object surface.
Claim 3
Dependent Claim
18 words
The method of claim 1, further comprising the step of: storing a tangent space perturbed normal texture map.
Claim 4
Dependent Claim
68 words
The method of claim 2, wherein said storing step stores a surface dependent tangent space perturbed normal texture map, said surface dependent tangent space perturbed normal texture map having texels defined by three perturbed normal components Nx', Ny', and Nz', said three perturbed normal components Nx', Ny', and Nz' representing in tangent space the differential surface behavior of the object surface when perturbed by a height field f(u,v).
Claim 5
Dependent Claim
86 words
The method of claim 3, wherein said three perturbed normal components Nx', Ny', and Nz' represent a perturbed normal in tangent space according to the following equations: ##EQU10## wherein coefficients a, b, c are given by: a=-ƒ.sub.u (B·P.sub.v) b=-(ƒ.sub.v |P.sub.u |-ƒ.sub.u (T·P.sub.v)) c=|P.sub.u ×P.sub.v |, B representing a normal vector, T representing a tangent vector, P u and P v representing respective partial derivatives of a surface position in u and v parametric directions and ƒ u and ƒ v are values in said height field.
Claim 6
Dependent Claim
67 words
The method of claim 2, wherein said storing stores a surface independent tangent space perturbed normal texture map, said surface independent tangent space perturbed normal texture map having texels defined by three perturbed normal components Nx', Ny', and Nz', said three perturbed normal components Nx', Ny', and Nz' approximating in tangent space the differential surface behavior of the object surface when perturbed by a height field f(u,v).
Claim 7
Dependent Claim
56 words
The method of claim 5, wherein said three perturbed normal components Nx', Ny', and Nz' approximate a perturbed normal in tangent space according to the following equations: ##EQU11## wherein coefficients a, b, c are given by: a=-kƒ.sub.u b=-(kƒ.sub.v) c=k.sup.2, where k is a constant and ƒ u and ƒ v are values in said height field.
Claim 8
Dependent Claim
20 words
The method of claim 2, wherein said storing step is performed during pre-processing prior to rendering the computer graphics image.
Claim 9
Dependent Claim
19 words
The method of claim 2, wherein said storing step is performed on-the-fly during rendering of the computer graphics image.
Claim 10
Dependent Claim
29 words
The method of claim 1, wherein said shading vector includes at least one of a lighting vector, a viewing vector, and a half angle vector and a reflection vector.
Claim 11
Dependent Claim
76 words
The method of claim 1, wherein the object surface is represented by triangles, and for each vertex of a triangle, said transforming step transforms a lighting vector and a viewing vector into a tangent space defined by said tangent space transform matrix to form corresponding tangent space lighting and viewing vectors, and further comprising the steps of: for each pixel, computing a tangent space half angle vector based on said tangent space lighting and viewing vectors.
Claim 12
Dependent Claim
99 words
The method of claim 10, wherein, said vector operation performing step calculates a first dot product between said tangent space lighting vector and said perturbed normal in tangent space for each pixel and a second dot product between said tangent space half angle vector and said perturbed normal in tangent space for each pixel, and said shaded value computing step computes said shading value based on a lighting equation having a diffuse component and a specular component raised to a specular power, said diffuse component includes said first dot product and said specular component includes said second dot product.
Claim 13
Dependent Claim
36 words
The method of claim 10, further comprising: for each pixel, prior to computing said tangent space half angle vector the step of: interpolating said tangent space lighting and viewing vectors across at least one corresponding triangle.
Claim 14
Dependent Claim
22 words
The method of claim 12, further comprising the step of: normalizing said tangent space lighting and viewing vectors after said interpolating step.
Claim 15
Dependent Claim
42 words
The method of claim 13, further comprising: for each pixel, the steps of: interpolating said tangent space half angle vector across at least one corresponding triangle; and normalizing said tangent space half angle after said tangent space half angle vector interpolating step.
Claim 16
Dependent Claim
26 words
The method of claim 10, further comprising: for each pixel, the step of: interpolating said tangent space half angle vector across at least one corresponding triangle.
Claim 17
Dependent Claim
25 words
The method of claim 15, further comprising the step of: normalizing said tangent space half angle after said tangent space half angle vector interpolating step.
Claim 18
Independent Claim
172 words
A system for shading a computer graphics image, the computer graphics image including an object surface, the system comprising: a tangent space transform module; a bump mapping module; and a lighting module; wherein said tangent space transform module builds a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface and transforms a shading vector at said point into a tangent space defined by said tangent space transform matrix to form a corresponding tangent space shading vector, said tangent space shading vector being output to said bump mapping module, and said bump mapping module performs a vector operation between said tangent space shading vector and a perturbed normal in tangent space at said point, and provides an output representative of said vector operation, and said lighting module computes a shading value for said point based on said vector operation output; whereby, said shading value can be mapped to a pixel to shade the object surface.
Claim 19
Independent Claim
172 words
A system for shading a computer graphics image, the computer graphics image including an object surface, the system comprising: a tangent space transform module; a bump mapping module; and a lighting module; wherein said tangent space transform module builds a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface and transforms a shading vector at said point into a tangent space defined by said tangent space transform matrix to form a corresponding tangent space shading vector, said tangent space shading vector being output to said bump mapping module, and said bump mapping module performs a vector operation between said tangent space shading vector and a perturbed normal in tangent space at said point, and provides an output representative of said vector operation, and said lighting module computes a shading value for said point based on said vector operation output; whereby, said shading value can be mapped to a pixel to shade the object surface.
Claim 20
Dependent Claim
19 words
The system of claim 17, further comprising a texture memory that stores a tangent space perturbed normal texture map.
Claim 21
Dependent Claim
63 words
The system of claim 18, wherein said tangent space perturbed normal texture map comprises a surface dependent tangent space perturbed normal texture map having texels defined by three perturbed normal components Nx', Ny', and Nz', said three perturbed normal components Nx', Ny', and Nz' representing in tangent space the differential surface behavior of the object surface when perturbed by a height field f(u,v).
Claim 22
Dependent Claim
86 words
The system of claim 19, wherein said three perturbed normal components Nx', Ny', and Nz' represent a perturbed normal in tangent space according to the following equations: ##EQU12## where coefficients a, b, c are given by: a=-ƒ.sub.u (B·P.sub.v) b=-(ƒ.sub.v |P.sub.u |-ƒ.sub.u (T·P.sub.v)) c=|P.sub.u ×P.sub.v | B representing a normal vector, T representing a tangent vector, P u and P v representing a partial derivative of a surface position in u and v parameter directions and ƒ u and ƒ v are values in said height field.
Claim 23
Dependent Claim
67 words
The system of claim 18, wherein said storing stores a surface independent tangent space perturbed normal texture map, said surface independent tangent space perturbed normal texture map having texels defined by three perturbed normal components Nx', Ny', and Nz', said three perturbed normal components Nx', Ny', and Nz' approximating in tangent space the differential surface behavior of the object surface when perturbed by a height field f(u,v).
Claim 24
Dependent Claim
56 words
The system of claim 21, wherein said three perturbed normal components Nx', Ny', and Nz' approximate a perturbed normal in tangent space according to the following equations: ##EQU13## where coefficients a, b, c are given by: a=-kƒ.sub.u b=-(kƒ.sub.v) c=k.sup.2, where k is a constant and ƒ u and ƒ v are values in said height field.
Claim 25
Dependent Claim
35 words
The system of claim 18, further comprising a texture map generator that generates said perturbed texture map and stores said perturbed texture map in said memory during pre-processing prior to rendering the computer graphics image.
Claim 26
Dependent Claim
34 words
The system of claim 18, further comprising a texture map generator that generates said perturbed texture map and stores said perturbed texture map in said memory on-the-fly during rendering of the computer graphics image.
Claim 27
Dependent Claim
28 words
The system of claim 17, wherein said shading vector includes at least one of a lighting vector, a viewing vector, a half angle vector, and a reflection vector.
Claim 28
Dependent Claim
78 words
The system of claim 17, wherein the object surface is represented by triangles, and for each vertex of a triangle, said tangent space transform module transforms a lighting vector and a viewing vector into a tangent space defined by said tangent space transform matrix to form corresponding tangent space lighting and viewing vectors; and for each pixel, said bump mapping module further computes a tangent space half angle vector based on said tangent space lighting and viewing vectors.
Claim 29
Dependent Claim
47 words
The system of claim 26, wherein said bump mapping module further comprises: an interpolator that interpolates said tangent space lighting and viewing vectors for each pixel across at least one corresponding triangle, and outputs an interpolated tangent space lighting vector and an interpolated tangent space viewing vector.
Claim 30
Dependent Claim
29 words
The system of claim 27, wherein said bump mapping module further comprises: a normalizer, coupled to said interpolator, said normalizer normalizes said interpolated tangent space lighting and viewing vectors.
Claim 31
Dependent Claim
40 words
The system of claim 26, wherein said bump mapping module further comprises: an interpolator that interpolates said tangent space half angle vector for each pixel across at least one corresponding triangle, and outputs an interpolated tangent space half angle vector.
Claim 32
Dependent Claim
23 words
The system of claim 29, wherein said bump mapping module further comprises: a normalizer that normalizes said interpolated tangent space half angle vector.
Claim 33
Dependent Claim
99 words
The system of claim 17, wherein, for each pixel, said bump mapping module calculates a first dot product between said tangent space lighting vector and said perturbed normal in tangent space for each pixel and a second dot product between said tangent space half angle vector and said perturbed normal in tangent space for each pixel, and said lighting module computes said shading value based on a lighting equation having a diffuse component and a specular component raised to a specular power, said diffuse component includes said first dot product and said specular component includes said second dot product.
Claim 34
Independent Claim
128 words
A system for shading an object surface, the system comprising: means for building a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; means for transforming a shading vector at said point into a tangent space defined by said tangent space transform matrix to form a corresponding tangent space shading vector; means for performing a vector operation between said tangent space shading vector and a perturbed normal in tangent space at said point; and means for computing a shading value for said point based on said vector operation; whereby, said shading value can be mapped to a pixel to shade the object surface when rendered on a computer graphics display.
Claim 35
Independent Claim
128 words
A system for shading an object surface, the system comprising: means for building a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; means for transforming a shading vector at said point into a tangent space defined by said tangent space transform matrix to form a corresponding tangent space shading vector; means for performing a vector operation between said tangent space shading vector and a perturbed normal in tangent space at said point; and means for computing a shading value for said point based on said vector operation; whereby, said shading value can be mapped to a pixel to shade the object surface when rendered on a computer graphics display.
Claim 36
Dependent Claim
176 words
A computer program product comprising a computer useable medium having computer program logic recorded thereon for enabling a graphics processor in a computer system to shade an object surface in a computer graphic image, said computer program logic comprising: means for enabling the graphics processor to build a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; means for enabling the graphics processor to transform a shading vector at said point into a tangent space defined by said tangent space transform matrix to form a corresponding tangent space shading vector; means for enabling the graphics processor to perform a vector operation between said tangent space shading vector and a perturbed normal in tangent space at said point; and means for enabling the graphics processor to compute a shading value for said point based on said vector operation; whereby, said shading value can be mapped to a pixel to shade the object surface rendered on a computer graphics display.
Claim 37
Dependent Claim
176 words
A computer program product comprising a computer useable medium having computer program logic recorded thereon for enabling a graphics processor in a computer system to shade an object surface in a computer graphic image, said computer program logic comprising: means for enabling the graphics processor to build a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; means for enabling the graphics processor to transform a shading vector at said point into a tangent space defined by said tangent space transform matrix to form a corresponding tangent space shading vector; means for enabling the graphics processor to perform a vector operation between said tangent space shading vector and a perturbed normal in tangent space at said point; and means for enabling the graphics processor to compute a shading value for said point based on said vector operation; whereby, said shading value can be mapped to a pixel to shade the object surface rendered on a computer graphics display.
Claim 38
Independent Claim
205 words
A method for shading a computer graphics image, the computer graphics image including an object surface, comprising the steps of: building a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; determining tangent space lighting and viewing vectors at said point in a tangent space defined by said tangent space transform matrix; generating a combination of images including an Lz TS image, a height field image, a z component diffuse image, and a shifted image sL, wherein said Lz TS image represents an unperturbed normal dotted with said tangent space lighting vector L TS , said height image represents a height field f(u,v) for bump mapping, said z component diffuse image represents a sum of said Lz image and said height image, and said shifted image approximates a partial sum sL equal to -(∂f/∂u)*Lx TS +-(∂f/∂v)*Ly TS ; generating a diffuse image based on the difference between said shifted image and said z component diffuse image; and forming a lit image based on at least said diffuse image; whereby, said lit image can be mapped as texture to the object surface when shading the computer graphics image.
Claim 39
Independent Claim
205 words
A method for shading a computer graphics image, the computer graphics image including an object surface, comprising the steps of: building a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; determining tangent space lighting and viewing vectors at said point in a tangent space defined by said tangent space transform matrix; generating a combination of images including an Lz TS image, a height field image, a z component diffuse image, and a shifted image sL, wherein said Lz TS image represents an unperturbed normal dotted with said tangent space lighting vector L TS , said height image represents a height field f(u,v) for bump mapping, said z component diffuse image represents a sum of said Lz image and said height image, and said shifted image approximates a partial sum sL equal to -(∂f/∂u)*Lx TS +-(∂f/∂v)*Ly TS ; generating a diffuse image based on the difference between said shifted image and said z component diffuse image; and forming a lit image based on at least said diffuse image; whereby, said lit image can be mapped as texture to the object surface when shading the computer graphics image.
Claim 40
Dependent Claim
164 words
The method of claim 34, further comprising the steps of: determining a tangent space half angle vector H TS at said point in a tangent space defined by said tangent space transform matrix; generating a combination of images including an Hz TS image, a height field image, a z component specular image, and a shifted image sH, wherein said Hz TS image represents an unperturbed normal dotted with said tangent space half angle vector H TS , said height image represents a height field f(u,v) for bump mapping, said z component specular image represents the sum of said Hz TS image and said height image, and said shifted image approximates a partial sum sH equal to -(∂f/∂u)*Hx TS +-(∂f/∂v)*Hy TS ; and generating a specular image based on the difference between said shifted image and said z component specular image; and wherein said forming a lit image step forms said lit image based on a combination of said diffuse image and said specular image.
Claim 41
Independent Claim
210 words
A method for shading a computer graphics image, the computer graphics image including an object surface, comprising the steps of: building a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; determining a tangent space half angle vector H TS at said point in a tangent space defined by said tangent space transform matrix; generating a combination of images including an Hz TS image, a height field image, a z component specular image, and a shifted image sH, wherein said Hz TS image represents an unperturbed normal dotted with said tangent space half angle vector H TS , said height image represents a height field f(u,v) for bump mapping, said z component specular image represents a sum of said Hz TS image and said height image, and said shifted image approximates a partial sum sH equal to -(∂f/∂u)*Hx TS +-(∂f/∂v)*Hy TS ; and generating a specular image based on the difference between said shifted image and said z component specular image; and forming a lit image based on at least said specular image; whereby, said lit image can be mapped as texture to the object surface when shading the computer graphics image.
Claim 42
Independent Claim
210 words
A method for shading a computer graphics image, the computer graphics image including an object surface, comprising the steps of: building a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; determining a tangent space half angle vector H TS at said point in a tangent space defined by said tangent space transform matrix; generating a combination of images including an Hz TS image, a height field image, a z component specular image, and a shifted image sH, wherein said Hz TS image represents an unperturbed normal dotted with said tangent space half angle vector H TS , said height image represents a height field f(u,v) for bump mapping, said z component specular image represents a sum of said Hz TS image and said height image, and said shifted image approximates a partial sum sH equal to -(∂f/∂u)*Hx TS +-(∂f/∂v)*Hy TS ; and generating a specular image based on the difference between said shifted image and said z component specular image; and forming a lit image based on at least said specular image; whereby, said lit image can be mapped as texture to the object surface when shading the computer graphics image.
Claim 43
Independent Claim
212 words
A system for shading a computer graphics image, the computer graphics image including an object surface, comprising: means for building a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; means for determining tangent space lighting and viewing vectors at said point in a tangent space defined by said tangent space transform matrix; means for generating a combination of images including an Lz TS image, a height field image, a z component diffuse image, and a shifted image sL, wherein said Lz TS image represents an unperturbed normal dotted with said tangent space lighting vector L TS , said height image represents a height field f(u,v) for bump mapping, said z component diffuse image represents a sum of said Lz image and said height image, and said shifted image approximates a partial sum sL equal to -(∂f/∂u)*Lx TS +-(∂f/∂v)*Ly TS ; means for generating a diffuse image based on the difference between said shifted image and said z component diffuse image; and means for forming a lit image based on at least said diffuse image; whereby, said lit image can be mapped as texture to the object surface when shading the computer graphics image.
Claim 44
Independent Claim
212 words
A system for shading a computer graphics image, the computer graphics image including an object surface, comprising: means for building a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; means for determining tangent space lighting and viewing vectors at said point in a tangent space defined by said tangent space transform matrix; means for generating a combination of images including an Lz TS image, a height field image, a z component diffuse image, and a shifted image sL, wherein said Lz TS image represents an unperturbed normal dotted with said tangent space lighting vector L TS , said height image represents a height field f(u,v) for bump mapping, said z component diffuse image represents a sum of said Lz image and said height image, and said shifted image approximates a partial sum sL equal to -(∂f/∂u)*Lx TS +-(∂f/∂v)*Ly TS ; means for generating a diffuse image based on the difference between said shifted image and said z component diffuse image; and means for forming a lit image based on at least said diffuse image; whereby, said lit image can be mapped as texture to the object surface when shading the computer graphics image.
Claim 45
Dependent Claim
168 words
The system of claim 37, further comprising: means for determining a tangent space half angle vector H TS at said point in a tangent space defined by said tangent space transform matrix; means for generating a combination of images including an Hz TS image, a height field image, a z component specular image, and a shifted image sH, wherein said Hz TS image represents an unperturbed normal dotted with said tangent space half angle vector H TS , said height image represents a height field f(u,v) for bump mapping, said z component specular image represents the sum of said Hz TS image and said height image, and said shifted image approximates a partial sum sH equal to -(∂f/∂u)*Hx TS +-(∂f/∂v)*Hy TS ; and means for generating a specular image based on the difference between said shifted image and said z component specular image; and wherein said means for forming a lit image forms said lit image based on a combination of said diffuse image and said specular image.
Claim 46
Independent Claim
216 words
A system for shading a computer graphics image, the computer graphics image including an object surface, comprising: means for building a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; means for determining a tangent space half angle vector H TS at said point in a tangent space defined by said tangent space transform matrix; means for generating a combination of images including an Hz TS image, a height field image, a z component specular image, and a shifted image sH, wherein said Hz TS image represents an unperturbed normal dotted with said tangent space half angle vector H TS , said height image represents a height field f(u,v) for bump mapping, said z component specular image represents the sum of said Hz TS image and said height image, and said shifted image approximates a partial sum sH equal to -(∂f/∂u)*Hx TS +-(∂f/∂v)*Hy TS ; means for generating a specular image based on the difference between said shifted image and said z component specular image; and means for forming a lit image based on at least said specular image; whereby, said lit image can be mapped as texture to the object surface when shading the computer graphics image.
Claim 47
Independent Claim
216 words
A system for shading a computer graphics image, the computer graphics image including an object surface, comprising: means for building a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; means for determining a tangent space half angle vector H TS at said point in a tangent space defined by said tangent space transform matrix; means for generating a combination of images including an Hz TS image, a height field image, a z component specular image, and a shifted image sH, wherein said Hz TS image represents an unperturbed normal dotted with said tangent space half angle vector H TS , said height image represents a height field f(u,v) for bump mapping, said z component specular image represents the sum of said Hz TS image and said height image, and said shifted image approximates a partial sum sH equal to -(∂f/∂u)*Hx TS +-(∂f/∂v)*Hy TS ; means for generating a specular image based on the difference between said shifted image and said z component specular image; and means for forming a lit image based on at least said specular image; whereby, said lit image can be mapped as texture to the object surface when shading the computer graphics image.
Claim 48
Independent Claim
192 words
A method for shading a computer graphics image, the computer graphics image including an object surface, comprising the steps of: building a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; determining tangent space lighting and viewing vectors at said point in a tangent space defined by said tangent space transform matrix; generating and mapping to the object surface a combination of images including an Lz TS image, a height field image, a z component diffuse image, and a shifted image sL, wherein said Lz TS image represents an unperturbed normal dotted with said tangent space lighting vector L TS , said height image represents a height field f(u,v) for bump mapping, said z component diffuse image represents a sum of said Lz image and said height image, and said shifted image approximates a partial sum sL equal to -(∂f/∂u)*Lx TS +-(∂f/∂v)*Ly TS ; generating a diffuse image based on the difference between said shifted image and said z component diffuse image; and forming a lit image based on at least said diffuse image.
Claim 49
Independent Claim
192 words
A method for shading a computer graphics image, the computer graphics image including an object surface, comprising the steps of: building a tangent space transform matrix, said tangent space transform matrix having elements comprised of normal, tangent, and binormal vector components determined at a point on the object surface; determining tangent space lighting and viewing vectors at said point in a tangent space defined by said tangent space transform matrix; generating and mapping to the object surface a combination of images including an Lz TS image, a height field image, a z component diffuse image, and a shifted image sL, wherein said Lz TS image represents an unperturbed normal dotted with said tangent space lighting vector L TS , said height image represents a height field f(u,v) for bump mapping, said z component diffuse image represents a sum of said Lz image and said height image, and said shifted image approximates a partial sum sL equal to -(∂f/∂u)*Lx TS +-(∂f/∂v)*Ly TS ; generating a diffuse image based on the difference between said shifted image and said z component diffuse image; and forming a lit image based on at least said diffuse image.
Claim 50
Dependent Claim
170 words
The method of claim 40, further comprising the steps of: determining a tangent space half angle vector H TS at said point in a tangent space defined by said tangent space transform matrix; generating and mapping to the object surface a combination of images including an Hz TS image, a height field image, a z component specular image, and a shifted image sH, wherein said Hz TS image represents an unperturbed normal dotted with said tangent space half angle vector H TS , said height image represents a height field f(u,v) for bump mapping, said z component specular image represents the sum of said Hz TS image and said height image, and said shifted image approximates a partial sum sH equal to -(∂f/∂u)*Hx TS +-(∂f/∂v)*Hy TS ; and generating a specular image based on the difference between said shifted image and said z component specular image; and wherein said forming a lit image step forms said lit image based on a combination of said diffuse image and said specular image.
Claim 51
Independent Claim
63 words
A system for shading a computer graphics image, comprising: Phong shading hardware; a texture memory for storing a tangent space perturbed normal texture map; and a switch coupled between said Phong shading hardware and said texture memory; whereby, tangent space bump mapping shades the computer graphics image when said switch is in a state connecting said texture memory to said Phone shading hardware.
Claim 52
Independent Claim
63 words
A system for shading a computer graphics image, comprising: Phong shading hardware; a texture memory for storing a tangent space perturbed normal texture map; and a switch coupled between said Phong shading hardware and said texture memory; whereby, tangent space bump mapping shades the computer graphics image when said switch is in a state connecting said texture memory to said Phone shading hardware.
Claim 53
Dependent Claim
21 words
The system of claim 42, wherein said switch couples said texture memory to a normalizer unit in said Phong shading hardware.
Claim 54
Dependent Claim
11 words
The system of claim 42, wherein said switch comprises a multiplexer.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-09-06 | 2003-03-08 | 2003-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-09-06 | 2007-03-08 | 2007-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-09-06 | 2011-03-08 | 2011-09-07 | $7700.00 | Window Closed / Lapsed |