Blended texture illumination mapping

• US 6,057,850 A
• Filed: 07/15/1997
• Issued: 05/02/2000
• Est. Priority Date: 07/15/1997
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Silicon Graphics Incorporated (Graphics Properties Holdings, Inc.)
• Inventors: Kichury, John J.
• Primary Examiner(s): Powell, Mark R.
• Assistant Examiner(s): HARRISON, CHANTE E
• Application Number:
  US08/895,258
• Time in Patent Office: 1,022 Days
• Field of Search: 345/419, 345/425, 345/426, 345/429, 345/430
• US Class Current: 345/584
• CPC Class Codes: G06T 15/503 Blending, e.g. for anti-aliasing

Abstract

A method and apparatus for expeditiously rendering realistic bumpy self-shadowed textured computer graphics is provide. Illuminated texture images of an object are obtained and stored in a data base as texture maps. These illuminated texture images are superimposed on top of each other and blended according to their weighted illumination contributions from the light sources to create a blended texture map. This blended texture map is then mapped to the desired surface of the geometric object.

Claims

1. A method to render blended texture illumination computer graphics, the method comprising the steps of:

generating a plurality of N illuminated texture images of a bumpy surface, wherein the N illuminated texture images depict the bumpy surface with a light source located at different positions,

blending the N illuminated texture images to produce the blended texture illumination.

2. The method of claim 1, wherein each of the N illuminated texture images is created by physically sampling the surface using a digital camera.

3. The method of claim 1, wherein each of the N illuminated texture images is created using a commercial modeling and rendering software package capable of bump mapping.

4. A method to render bumpy self-shadowed textured computer graphics, the method comprising the steps of:

creating a plurality of N illuminated texture images of a bumpy surface, wherein the N illuminated texture images are created by positioning a light source at predetermined positions;

mapping the N illuminated texture images to a selected surface of a geometric model of an object based on illumination contribution from a light source;

superimposing the N illuminated texture images on top of each other; and

blending the N illuminated texture images according to an illumination equation;

##EQU3## where intensity is a combined pixel intensity at (x,y) to be computed, image i is an illuminated texture image pixel normalized intensity, N is the number of illuminated texture images, Light is a normalized light vector from a center of an illuminated texture image to a light source, and DirVec_i is a normalized direction vector paired with the illuminated texture image_i ;

wherein resulting values of (Light·

DirecVec_i) are clamped between 0-1.

5. A method to render bumpy self-shadowed textured computer graphics, the method comprising the steps of:

a) creating a geometric model of an object;

b) creating a plurality of N illuminated texture images of a bumpy surface having at least two illuminated texture images, wherein each of the N illuminated texture images is created by positioning a light source at a predetermined position; and

c) mapping the N illuminated texture images to a selected surface of the geometric model of the object by performing the following steps;

d) disabling blending function;

e) setting depth function to allow coplanar rendering;

f) enabling depth buffer;

g) enabling shading function;

h) disabling graphics substantive lighting function;

i) drawing the object in ambient lighting;

j) enabling blending function;

k) selecting an illuminated texture image;

l) selecting a vertex of the selected surface;

m) computing red, green, blue (RGB) and transparency (Alpha) values based on illumination contribution from the light source;

n) drawing the selected vertex of the selected surface using the RGB and Alpha values computed;

o) repeating steps (l)-(n) for all vertices of the selected surface; and

p) repeating steps (k)-(o) for all illuminated texture images.

6. The method of claim 5, wherein the N illuminated texture images include at least nine illuminated texture images.

7. The method of claim 6, wherein each of the N illuminated texture images is created by physically sampling the surface using a digital camera.

8. The method of claim 6, wherein each of the N illuminated texture images is created using a commercial modeling and rendering software package capable of bump mapping.

9. The method of claim 5, wherein the shading function is Gouraud Interpolation.

10. The method of claim 6, wherein illumination contribution from the light source is calculated according to:

space="preserve" listing-type="equation">intensity(x,y)=clamp(Light·

DirVec.sub.i)

where intensity is a pixel intensity at (x,y) to be computed, Light is a normalized light vector from a center of the illuminated texture image to the light source, and DirVec_i is a normalized direction vector paired with the illuminated texture image;

wherein resulting value of (Light·

DirVec_i) is clamped between 0-1.

11. A computer system adapted to render bumpy self-shadowed textured computer graphics, the computer system comprising:

a bus;

a processor coupled to the bus;

memory coupled to the bus, the memory storing a geometric model of an object and a plurality of N illuminated texture images of a bumpy surface, wherein the N illuminated texture images are blended together according to an illumination contribution of a light source.

12. The computer system of claim 11, wherein the N illuminated texture images include at least nine illuminated texture images.

13. The computer system of claim 12, wherein each of the N illuminated texture images is created by physically sampling the surface using a digital camera.

14. The computer system of claim 12, wherein each of the N illuminated texture images is created using a commercial modeling and rendering software package capable of bump mapping.

15. The computer system of claim 11, wherein the shading function is Gouraud Interpolation.

17. The computer system of claim 11, wherein the processor maps the N illuminated texture images to the selected surface of the geometric model of the object according to the steps of:

a) disabling blending function;

b) setting depth function to allow coplanar rendering;

c) enabling depth buffer;

d) enabling shading function;

e) disabling graphics substantive lighting function;

f) drawing the object in ambient lighting;

g) enabling blending function;

h) selecting an illuminated texture image;

i) selecting a vertex of the selected surface;

j) computing red, green, blue (RGB) and transparency (Alpha) values based on illumination contribution from the light source;

k) drawing the selected vertex of the selected surface using the RGB and Alpha values computed;

l) repeating steps (i)-(k) for all vertices of the selected surface; and

m) repeating steps (h)-(l) for all illuminated texture images.

16. A computer system adapted to render bumpy textured computer graphics, the computer system comprising:

a processor coupled to the bus;

memory coupled to the bus, the memory storing a geometric model of an object and a plurality of N illuminated texture images of a bumpy surface, the memory further storing instruction codes, the instruction codes, when executed by the processor, maps the N illuminated texture images to a selected surface of the geometric model of the object, the N illuminated texture images including at least two illuminated texture images, wherein illumination contribution from the light source is calculated according to;

space="preserve" listing-type="equation">intensity (x,y)=clamp(Light·

DirVec.sub.i)

where intensity is a pixel intensity at (x,y) to be computed, Light is a normalized light vector from a center of an illuminated texture image to a light source, and DirVec_i is a normalized direction vector paired with the illuminated texture image;

wherein resulting values of (Light·

DirecVec_i) are clamped between 0-1.