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Page 1: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

Graphics

cgvr.korea.ac.kr 1 Graphics Lab @ Korea University Graphics Lab @ Korea University

Texture Mapping

고려대학교 컴퓨터 그래픽스 연구실

Page 2: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

2 Graphics Lab @ Korea University Graphics Lab @ Korea University

3D Rendering Pipeline

Model TransformationModel Transformation

LightingLighting

Viewing TransformationViewing Transformation

Projection TransformationProjection Transformation

ClippingClipping

Viewport TransformationViewport Transformation

Scan ConversionScan Conversion

3D Primitives

Image

3D Modeling Coordinates

3D World Coordinates

3D World Coordinates

3D Viewing Coordinates

2D Projection Coordinates

2D Projection Coordinates

2D Device Coordinates

2D Device Coordinates

TextureMapping

Page 3: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

3 Graphics Lab @ Korea University Graphics Lab @ Korea University

Textures

Color variation in interior of 3D polygon When scan converting a polygon

Vary pixel colors according to values fetched from a texture

s

t

Texture

y

z

x

Surface

ys

xsImage

Page 4: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

4 Graphics Lab @ Korea University Graphics Lab @ Korea University

Texture Surface

Add Visual Detail to Surfaces of 3D Objects

Polygonal Model

With Surface Texture

Page 5: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

5 Graphics Lab @ Korea University Graphics Lab @ Korea University

Overview

Texture mapping methods Mapping Filtering

Texture mapping applications Modulation textures Illumination mapping Bump mapping Environment mapping Image-based rendering Non-photorealistic rendering

Page 6: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

6 Graphics Lab @ Korea University Graphics Lab @ Korea University

Texture Mapping

Steps: Define texture Specify mapping from texture to surface Lookup texture values during scan conversion

TextureCoordinate

System

ModelingCoordinate

System

DeviceCoordinate

System

s

tvu

(0,1)

(0,0)

(1,0)y

x

Page 7: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

7 Graphics Lab @ Korea University Graphics Lab @ Korea University

Texture Mapping

When scan converting Device coordinate system (x,y) Modeling coordinate system (u,v) Texture image (t,s)

TextureCoordinate

System

ModelingCoordinate

System

DeviceCoordinate

System

s

tvu

(0,1)

(0,0)

(1,0)y

x

Page 8: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

8 Graphics Lab @ Korea University Graphics Lab @ Korea University

Texture Mapping

2D projective transformation Texture coordinate system (t,s) to Device coordinate system (x,y)

Page 9: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

9 Graphics Lab @ Korea University Graphics Lab @ Korea University

Texture Mapping

Scan conversion Interpolate texture coordinates Distortion due to bilinear interpolation approximation

Cut polygons into smaller ones, or Perspectively divide at each pixel

α βγ

(u1, v1)

(u3, v3)(u2, v2)

Page 10: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

10 Graphics Lab @ Korea University Graphics Lab @ Korea University

Texture Mapping

Linear Interpolationof Texture Coordinate

Corrected Interpolationwith Perspective Divide

Page 11: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

11 Graphics Lab @ Korea University Graphics Lab @ Korea University

Texture Mapping

Texture mapping methods Mapping Filtering

Texture mapping applications Modulation textures Illumination mapping Bump mapping Environment mapping Image-based rendering Non-photorealistic rendering

Page 12: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

12 Graphics Lab @ Korea University Graphics Lab @ Korea University

Texture Filtering

Must sample texture to determine color at each pixel in image

s

t

y

z

x

ys

xs

Page 13: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

13 Graphics Lab @ Korea University Graphics Lab @ Korea University

Texture Filtering

Aliasing is a problem

Point Sampling Area Filtering

Page 14: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

14 Graphics Lab @ Korea University Graphics Lab @ Korea University

Texture Filtering

Ideally, use elliptically shaped convolution filters In practice, use rectangles

Texture

Screen

Page 15: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

15 Graphics Lab @ Korea University Graphics Lab @ Korea University

Texture Filtering

Size of filter depends on projective warp Prefiltering images

Mip maps Summed area tables

s

t

ys

xs

Texel

Pixel

s

t

ys

xs

Texel

Pixel

Magnification Minification

Page 16: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

16 Graphics Lab @ Korea University Graphics Lab @ Korea University

Mip Maps

Keep textures prefiltered at multiple resolutions For each pixel, linearly interpolate between two

closest levels (e.g., trilinear filtering) Fast and easy for hardware

Page 17: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

17 Graphics Lab @ Korea University Graphics Lab @ Korea University

Overview

Texture mapping methods Mapping Filtering

Texture mapping applications Modulation textures Illumination mapping Bump mapping Environment mapping Image-based rendering Non-photorealistic rendering

Page 18: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

18 Graphics Lab @ Korea University Graphics Lab @ Korea University

Modulation Texture

Map Texture Values to Scale FactorW

ood

Textu

re

))RV((, TTRSL LLn

SDAAE IKIKISKLNKIKIstTI ))RV((, TTRSL LLn

SDAAE IKIKISKLNKIKIstTI

TextureValue

Page 19: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

19 Graphics Lab @ Korea University Graphics Lab @ Korea University

Illumination Mapping

Map Texture Values to Surface Material Parameter KA

KD

KS

KT

n

TTRSL LLn

SDAAE IKIKISKLNKIKII )RV( TTRSL LLn

SDAAE IKIKISKLNKIKII )RV(

stTKT ,

Page 20: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

20 Graphics Lab @ Korea University Graphics Lab @ Korea University

Bump Mapping

Map Texture Values to Perturbations of Surface Normals

Page 21: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

21 Graphics Lab @ Korea University Graphics Lab @ Korea University

Bump Mapping

Page 22: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

22 Graphics Lab @ Korea University Graphics Lab @ Korea University

Environmental Mapping

Map Texture Values to the Environment Map

Surface

ProjectionReference Point

Pixel Area

Pixel Projectiononto Environment

Map

Page 23: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

23 Graphics Lab @ Korea University Graphics Lab @ Korea University

Image-Based Rendering

Map Photographic Textures to Provide Details for Coarsely Detailed Polygonal Model

Page 24: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

24 Graphics Lab @ Korea University Graphics Lab @ Korea University

Nonphotorealistic Rendering

Page 25: Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Texture Mapping 고려대학교 컴퓨터 그래픽스 연구실

cgvr.korea.ac.kr

CGVR

25 Graphics Lab @ Korea University Graphics Lab @ Korea University

Summary

Texture mapping methods Mapping Filtering

Texture mapping applications Modulation textures Illumination mapping Bump mapping Environment mapping Image-based rendering Non-photorealistic rendering