Embed Size (px)
Citation preview
13th UWA CSSE Research Conference, Yanchep, Western Australia, 20th-21st September 2004. Slide 1 of 13
Keeping Faces StraightView Morphing for Graphics
TzuYen WongSupervised by Peter Kovesi & Amitava Datta
13th UWA CSSE Research Conference, Yanchep, Western Australia, 20th-21st September 2004. Slide 2 of 13
• Morphing – fluid transition• View morphing – taking
viewpoint into account– Straight lines remain straight
during the morph
• In 3D computer graphics
Introduction
Keeping Faces Straight - View Morphing for Graphics
13th UWA CSSE Research Conference, Yanchep, Western Australia, 20th-21st September 2004. Slide 3 of 13
• Motivations• Image morphing review• View morphing• Validation Results• Future Work
Outline
13th UWA CSSE Research Conference, Yanchep, Western Australia, 20th-21st September 2004. Slide 4 of 13
• Computer graphics models become more detailed– millions of triangles to represent a model
• Graphics rendering cost model complexity∝• Image morphing cost image size∝• Key frames - rendering • Transition frames - morphing
Motivation 1: Why Morphing for Graphics?
13th UWA CSSE Research Conference, Yanchep, Western Australia, 20th-21st September 2004. Slide 5 of 13
• Linear morphing path does not preserve 3D shapes
• View morphing by Seitz utilises computer vision principles to guarantee physically valid transition
Motivation 2: Why View Morphing?
13th UWA CSSE Research Conference, Yanchep, Western Australia, 20th-21st September 2004. Slide 6 of 13
Image Morphing Review• Interpolation of shape and colour
Cross dissolving
Image Warping
Image Warping
13th UWA CSSE Research Conference, Yanchep, Western Australia, 20th-21st September 2004. Slide 7 of 13
Image Morphing Review (cont.)• Pioneered at Industrial Light & Magic:
– Mesh morphing (Smythe 1988)
• Various improvements: – Feature line pairs (Beier & Neely 1992)
– Feature polylines, curves and points
– Automatic feature specification (Gao 1998)
– Warp generation as scattered data interpolation
– Transition control (Lee 1995)
– Shape preservation (Seitz 1996, Xiao 2004)
13th UWA CSSE Research Conference, Yanchep, Western Australia, 20th-21st September 2004. Slide 8 of 13
View Morphing:Parallel View
• Linear interpolation of point position is shape preserving in parallel view
X
x1
x2C1
C2
f1
f2
I1
I2
0100
00
00
P ,
0100
000
000
P 22
22
21
1
1 y
x
Cff
Cff
f
f
)0,,(C )0,0,0(C X P x 21 yx CC
x2+x2
C
f
I
21 x x)-(1 x
21
22
)-(1
) 0 , , (C
fff
CC yx
X P P )-(1 X P 21
13th UWA CSSE Research Conference, Yanchep, Western Australia, 20th-21st September 2004. Slide 9 of 13
X
C1
C2
I1
I2
View Morphing:Non-Parallel View
• Three steps algorithm:– Prewarp: reproject non-
parallel views I1 & I2 into parallel views Î1 & Î2
– Morph: create Î by linearly interpolating Î1 & Î2
– Postwarp: reproject Î to the desired camera configuration and yield image I .
• Three steps algorithm:– Prewarping
– Morphing
– Postwarping
C
I^
Morphing
– Morph: create Î by linearly interpolating Î1 & Î2
I
Postwarping
– Postwarp: reproject Î to the desired camera configuration and yield image I .
I1^
I2^
Prewarping• Three steps algorithm:
– Prewarp: reproject non-parallel views I1 & I2 into parallel views Î1 & Î2
13th UWA CSSE Research Conference, Yanchep, Western Australia, 20th-21st September 2004. Slide 10 of 13
Validation Results –Non-straight Faces
DesiredViews
Linearinterpolation
13th UWA CSSE Research Conference, Yanchep, Western Australia, 20th-21st September 2004. Slide 11 of 13
Validation Results – Straight Faces
PrewarpingMorphing
Postwarping
13th UWA CSSE Research Conference, Yanchep, Western Australia, 20th-21st September 2004. Slide 12 of 13
1. Epipoles inside images
2. Automatic feature correspondence
3. Warp generation error measurements
4. Edges behaviour
5. Optimisation of computation on hardware
Future Work
13th UWA CSSE Research Conference, Yanchep, Western Australia, 20th-21st September 2004. Slide 13 of 13
Keeping Faces StraightView Morphing for Graphics
TzuYen WongSupervised by Peter Kovesi & Amitava Datta
