Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Chapter 6 Special Effects 강 신 진강...
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Transcript of Graphics Graphics Lab @ Korea University cgvr.korea.ac.kr 1 Chapter 6 Special Effects 강 신 진강...
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cgvr.korea.ac.kr 1 Graphics Lab @ Korea University
Chapter 6 Special Effects
강 신 진
2002.04.242002.04.24
cgvr.korea.ac.kr
CGVR
2 Graphics Lab @ Korea University
What?
What is Special Effects? Relative term in computer graphics New way of performing old algorithms
온라인 게임 - 뮤
cgvr.korea.ac.kr
CGVR
3 Graphics Lab @ Korea University
Index
Image-Based Rendering Lens Flare and Bloom Billboarding Full-Screen Billboarding Particle System Fixed-View Effects
Motion Blur Depth of Field Reflections
Planar Reflections Glossy Effects Reflections from Curved Reflectors
cgvr.korea.ac.kr
CGVR
4 Graphics Lab @ Korea University
Polygon-Based Rendering Use polygon to portray image Can represent the object in any view
Image-Based Rendering Use images to portray image Can gain speed advantage
Image-Based Rendering
cgvr.korea.ac.kr
CGVR
5 Graphics Lab @ Korea University
Image-Based Rendering - Sprite
What is Sprite? An Image that moves around on the screen Simplest image-base rendering primitive
Implementation An image texture on a polygon with the use of alpha
channel
+ =
배경화면 스프라이트 결과화면
cgvr.korea.ac.kr
CGVR
6 Graphics Lab @ Korea University
Image-Based Rendering - Sprite
Example
Matrox Graphics Power of 3D Demo
cgvr.korea.ac.kr
CGVR
7 Graphics Lab @ Korea University
Image-Based Rendering - Sprite
Example
Matrox Graphics Power of 3D Demo
cgvr.korea.ac.kr
CGVR
8 Graphics Lab @ Korea University
Image-Based Rendering – QuickTime VR
QuickTime VR Use a 360` panoramic image surrounds the viewer
as a cylindrical image Optimized for cylindrical environment mapping
cgvr.korea.ac.kr
CGVR
9 Graphics Lab @ Korea University
Image-Based Rendering
Limitation When to Warp and When to Regenerate?
Microsoft Chicken Crossing
cgvr.korea.ac.kr
CGVR
10 Graphics Lab @ Korea University
Index
Image-Based Rendering Lens Flare and Bloom Billboarding Full-Screen Billboarding Particle System Fixed-View Effects
Motion Blur Depth of Field Reflections
Planar Reflections Glossy Effects Reflections from Curved Reflectors
cgvr.korea.ac.kr
CGVR
11 Graphics Lab @ Korea University
Lens Flare and Bloom
Sample
nVIDIA Effect Browser
cgvr.korea.ac.kr
CGVR
12 Graphics Lab @ Korea University
Lens Flare and Bloom
Lens Flare Phenomenon caused by the lens of the eye or
camera when directed at bright light Consist of Halo and Ciliary Corona
Bloom Phenomenon caused by scattering in the lens and
other part of the eye Halo
Ciliary Corona
Bloom
cgvr.korea.ac.kr
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13 Graphics Lab @ Korea University
Lens Flare and Bloom
Sample
nVIDIA Effect Browser
cgvr.korea.ac.kr
CGVR
14 Graphics Lab @ Korea University
Billboarding
Billboarding Orienting the polygon based on the view direction
Billboard The polygon which is oriented
Direct3D Billboarding Tree
cgvr.korea.ac.kr
CGVR
15 Graphics Lab @ Korea University
Billboarding – Screen-Aligned
Screen-Aligned Billboarding Billboard face the screen Billboard normal is negation of the view direction Rotate n to align with –Vdir, the rotate u’ to align with
Vup
u’
Vup
Vdir
n
cgvr.korea.ac.kr
CGVR
16 Graphics Lab @ Korea University
World-Aligned Billboarding Billboard face the screen but aligns with the world’s
up-vector Wup
Billboarding – World-Aligned
dirup VWr rVt dirup
tup
Wup
Vdir
rn
cgvr.korea.ac.kr
CGVR
17 Graphics Lab @ Korea University
Axial-Aligned Billboarding Billboard rotate around fixed world-space axis and
align with viewer as possible within range
Billboarding – Axial-Aligned
updir WVs sWt updir
tdir
WupVdir
s
cgvr.korea.ac.kr
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18 Graphics Lab @ Korea University
Full-Screen Billboarding
Full-Screen Billboarding A Screen-align billboard that covers the entire view Can change the look of an environment
id Software Quake III
cgvr.korea.ac.kr
CGVR
19 Graphics Lab @ Korea University
Index
Image-Based Rendering Lens Flare and Bloom Billboarding Full-Screen Billboarding Particle System Fixed-View Effects
Motion Blur Depth of Field Reflections
Planar Reflections Glossy Effects Reflections from Curved Reflectors
cgvr.korea.ac.kr
CGVR
20 Graphics Lab @ Korea University
Particle Systems
Particle System A set of separate small objects that are set into
motion using some algorithm Creating, moving, changing, and deleting particles
nVIDIA Particle Demo
cgvr.korea.ac.kr
CGVR
21 Graphics Lab @ Korea University
Fixed-View Effects
Fixed-View The view is fixed to one location and orientation Using depth information from a real scene to be seen
more realistic Static image can be made to look more realistic
3D 수족관 화면 보호기
cgvr.korea.ac.kr
CGVR
22 Graphics Lab @ Korea University
Index
Image-Based Rendering Lens Flare and Bloom Billboarding Full-Screen Billboarding Particle System Fixed-View Effects
Motion Blur Depth of Field Reflections
Planar Reflections Glossy Effects Reflections from Curved Reflectors
cgvr.korea.ac.kr
CGVR
23 Graphics Lab @ Korea University
Motion Blur
Blurring Can add the feeling of motion Average a series of images using accumulation
buffer
Motion Blur created by accumulation buffer
cgvr.korea.ac.kr
CGVR
24 Graphics Lab @ Korea University
Index
Image-Based Rendering Lens Flare and Bloom Billboarding Full-Screen Billboarding Particle System Fixed-View Effects
Motion Blur Depth of Field Reflections
Planar Reflections Glossy Effects Reflections from Curved Reflectors
cgvr.korea.ac.kr
CGVR
25 Graphics Lab @ Korea University
Depth of Field
Depth of Field Objects which is out of focus are blurry
nVIDIA Depth of Field
cgvr.korea.ac.kr
CGVR
26 Graphics Lab @ Korea University
Index
Image-Based Rendering Lens Flare and Bloom Billboarding Full-Screen Billboarding Particle System Fixed-View Effects
Motion Blur Depth of Field Reflections
Planar Reflections Glossy Effects Reflections from Curved Reflectors
cgvr.korea.ac.kr
CGVR
27 Graphics Lab @ Korea University
Reflections
Reflection and Shadows Generated by lighting equation Can increase realism Used by viewer as a cues to determine spatial
relationships between objects
cgvr.korea.ac.kr
CGVR
28 Graphics Lab @ Korea University
Reflections
Reflector and Reflected Geometry Reflector: a reflecting surface Reflected Geometry: Geometry reflected in the
reflector
Ray Tracing Solution in which the reflection ray is emitted from a
reflector and recursively traced Computationally intensive for real-time system Need real-time solution
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29 Graphics Lab @ Korea University
Reflections – Planar Reflections
Planar Reflection Reflection off a flat surface - Mirror reflection Execute more rapidly than general reflection Follows the law of reflection
Can be Implemented by Copy & Transforming
cgvr.korea.ac.kr
CGVR
30 Graphics Lab @ Korea University
Reflections – Planar Reflections
Reflection Matrix F = R (n, (0,1,0))T(-p) M = F-1 S(1,-1,1) F
cgvr.korea.ac.kr
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31 Graphics Lab @ Korea University
Reflections – Planar Reflections
Reflectivity factor Applied by changing transparency
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32 Graphics Lab @ Korea University
Reflections – Planar Reflections
Stencil Buffer Support selective Planar Reflections
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33 Graphics Lab @ Korea University
Reflections – Planar Reflections
Problem Area Culling
Turn off face culling or front face culling
Clipping Clipping Plane
Another Technique Reflection image can be treated as a texture
cgvr.korea.ac.kr
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34 Graphics Lab @ Korea University
Glossy Effects
Glossy Effects Object face to black as the distance from the reflector
increase Distance calculation is needed
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35 Graphics Lab @ Korea University
Reflections from Curved Reflector
Traditional Solution Ray-Tracing Not good for real-time system
Selective Trace Ray Trace rays only from the reflector’s vertices into
environment Significantly reduce computation time but still suffer
from Gouraud-Shading artifacts
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36 Graphics Lab @ Korea University
Question
Image-Based Rendering Lens Flare and Bloom Billboarding Full-Screen Billboarding Particle System Fixed-View Effects
Motion Blur Depth of Field Reflections
Planar Reflections Glossy Effects Reflections from Curved Reflectors
Matrox Graphics Power of 3D Demo