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From 2D Images to 3D Tangible Models: Reconstruction and Visualization of Martian Rocks Cagatay Basdogan, Ph.D. College of Engineering Koc University. The Old Story ...(July 04, 1997). Sojourner. The New Story ...January 04, 2004. Our goal. From 2D Images to 3D Models. Acquisition. - PowerPoint PPT Presentation
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EURON Summer School 2003
From 2D Images to 3D Tangible Models:Reconstruction and Visualization
of Martian Rocks
Cagatay Basdogan, Ph.D.College of Engineering
Koc University
EURON Summer School 2003
The Old Story ... (July 04, 1997)
Sojourner
EURON Summer School 2003
The New Story ... January 04, 2004
EURON Summer School 2003
Rock
Our goal ...
EURON Summer School 2003From 2D Images to 3D Models
rock
Range surfaces
registrationintegration
Acquisition Visualization
Reconstruction Transmission
Left Right 1
2
4
3
EURON Summer School 2003
Limitations ...
• CPU: 2MHz 2 GHz • Memory: 768Kb 256 Mb + 40 Gb• Transmission Rate: <5 bytes/sec 100 Mb/sec• Transmission Delay ~ 20 min. < 200 msec• Transmission Interval ~ 2 hours anytime• Transmission Reliability poor good
Sojourner Laptop
EURON Summer School 2003
Octree-BasedData Representation
and Integration
Range surfaces
ProgressiveTransmission
Merged Range Data
Multi-Resolution Transmitted Range Data
Iso-surfaceExtraction
3D Model
Registration
Transformed Range surfaces1
2
3
1 2
3
Image-Based Rendering
Data Acquisition
EURON Summer School 2003
Data Acquisition
JPL – Marsyard (http://marsyard.jpl.nasa.gov)
EURON Summer School 2003
Input: Range Scans
Left Image Right Image
3D range surface:coordinatesconnectivity
EURON Summer School 2003
3D Reconstruction
Range Surface 2
Range Surface 1 1. Registration
2. Integration
Range Surface 3
Top View
1
2
3
EURON Summer School 2003
3D Registration
Pair-wise registration problem: Given 2 overlapping range scans what is the rigid transformation, T,that minimizes the distance between them ?
T
QP
||||2
iiE TqpN
i
Solution: ICP algorithm (Besl and Kay, 1992)
doIdentify corresponding pointsCompute the optimal T
while (E < threshold)
EURON Summer School 2003
3D Registration : Computation of T
||)(||2
tRqp iiEN
i
R: Rotation Matrixt: translation vector
2/1)( MMMR T
Solution by Horn, 1990:
where,
Tii
N
i
qqppM ))((
qRpt
EURON Summer School 2003
3D Registration: Corresponding Points
Q
P
We now have a closed form solution, how do we get the corresponding points in two scans?
Nearest points along the direction of the normal at qi
Top View
1 2
3
EURON Summer School 2003
3D Integration
Problem: Given a set of registered range scans, reconstruct a 3D surface that closely approximates the original shape.
Methods:
• Delaunay-Based (Amenta et al., Siggraph’98)• Surface-Based (Turk and Levoy, Siggraph’94)• Volumetric (Curless and Levoy, Siggraph’96)
Computationally ComplexityRobustnessMemory Usage...
Which one is better ?
EURON Summer School 2003
3D Integration: Volumetric Approach
Our implementation:
Step 1: Merge the registered range surfaces using an octree
Step 2:Extract an isosurface using the Marching Cubes algorithm
Input:registered
range surfaces
VolumetricIntegration
Output:3D Mesh
EURON Summer School 2003
3D Integration (Step 1): Merge Range Images
rock
Mesh 1
Mesh 2
Mesh 3
Registered
Merged(no connectivity)
EURON Summer School 2003
root Level 0
Level 1
Level 2
3D Integration (Step 1): Data Representation Using an Octree
Weightedaveraging
Yemez & Schmitt, 1999
EURON Summer School 2003
Original Model: 47724 points
Max 50 points/octant Total: 1870 points
Max 100 points/octant Total: 1052 points
Max 500 points/octant Total: 273 points
2D Example: QuadtreeMax 1 point/rectangle
Data Reduction Using an Octree
EURON Summer School 2003Octree Representation: Our Implementation
root
1 2 3 4
1 2 3 4 1 2 3 4
1 2 3 4
1 2 3 4
Level 0
Level 1
Level 2
Level 3
1 2
3 4Reference:
Path : 1 3 1 1center
=estimatedcoordinateand shape
EURON Summer School 2003
0 1 1 0 0 0 1 0
1 0 1 1 0 0 0 0 0 0 0 1 0 0 1 0
0 12 3
4
56
0 1
2 345
6
0 1
2 345
6
0 1
2 345
6
1 0 0 0 0 0 0 1
0 1
2 345
6
1 0 0 0 1 0 0 0
octree root layer 0
layer 16
0
4
layer 2
layer 3
Octree Encoding
Yemez & Schmitt, 1999
Our implementation:
EURON Summer School 2003
Octrees for 3D Progressive Data Transmission
root Level 0
Level 1
Level 2
Level 5
Level 8
.
.
.
.
215 points
2813 points
5823 points
EURON Summer School 2003
3D Integration (Step 2): Iso-surface Extraction
ProgressiveTransmission
Merged Data
Transmitted Data
Iso-surfaceExtraction:
Marching Cubes
3D Mesh
v1x v1y v1zv2x v2y v2z…rgb1rgb2...n1x n1y n1zn2x n2y n2z...
Coordinates
Colors
Normals
High Priority
Low Priority
EURON Summer School 2003
2-D Example
INOUT
24 = 16 possible cases
3D Integration (Step 2): Marching Cubes
isoline
+0.3 -0.5
+0.4+0.8
EURON Summer School 2003
28 = 256 possible cases(a look-up table reduces to 15 cases)
(Lorensen et al., Siggraph’87)Marching Cubes Algorithm : 3D Case
EURON Summer School 2003
3D Integration: Step 2: Signed Distance Computation
isos
urfa
ce
-0.7 +0.1
+0.4-0.3
Voxel (IN)
Voxel (OUT)n1 n2
v1
v2
dot(v1,n1) > 0 IN, distance = -|v1|
dot(v2,n2) < 0 OUT, distance = +|v2|
Signed Distance:
EURON Summer School 2003
Can I estimate Normals?
Problem: Given a set of P unorganized sample points, estimate the point normals.
Algorithm by Hoppe (Siggraph’92):
Step 1: Tangent Plane Estimation
Step 2: Consistent Tangent Plane Orientation
EURON Summer School 2003
1. Tangent Plane Estimation
R ~ (
Noise Density
R
Sample point
Centeroid
Neighbor
N
Use covariance matrix to compute NSVD : eigenvalues :
eigenvectors : vvv
Nv
v
N ?
N ?
EURON Summer School 2003
Incorrect Surface Normals
Corrected Surface Normals
MST: A minimal spanning tree fora connected graph
4
8 7
9
10
144
6
2
12
11
8
2. Consistent Tangent Plane Orientation: Graph Optimization Problem
Cost on edge: 1 –Ni.Nj
Propagate along directions of low curvature!
Ni NjNj
Ni
EURON Summer School 2003
point-based rendering with colors
EURON Summer School 2003
Iso-surfaceExtraction
3D Mesh3D Texture
3D Visualization
EURON Summer School 2003
Autostereoscopic Visualization
3D Visualization without any eye wear !
Stereoscopic viewing Autostereoscopic viewing
Src: Stereographics Inc.
EURON Summer School 2003
LCDRLCDL
HolographicOptical Element
eyeReyeL
Stereoscopic viewing Autostereoscopic viewing
Stereoscopic Visualization
EURON Summer School 2003
Autostereoscopic Displays
Relatively new area !
Hale et al., 1997, SiggraphPerlin et al., 2000, Siggraph
• Re-imaging displays• Volumetric displays• Parallax displays
Classification by Hale et al.:
• Holograms• Parallax Barrier Displays• Lenticular Sheet Displays• Holographic Stereograms• Electro-Holography
holographic optical element
EURON Summer School 2003
CameraPosition
Far
Dis
tanc
e
Nea
r D
ista
nce
Width A
ngle
Height Angle
HolographicPlate
Origin (0,0,0)
CameraPosition
b) AsymmetricFrustum
a) SymmetricFrustum
ShearDirection
Stereo Rendering : Shear Transform
EURON Summer School 2003
AutostereoscopicDisplay
HapticInterface
r
x
yz
v
wL
wR
1
0)(tan
wvQ
wvI T
S
Shear Transform:
1000
01
0010
0001
z
y
z
xcamera
r
r
r
rS
zyx rrrEye pos:
EURON Summer School 2003
Haptic Visualization
• Rendering rock textures• Displaying 3D rock shapes• Tele-science experiments• Guiding user’s movements• Positioning rover instruments
HIP
EURON Summer School 2003
Haptic Display of Shape
CollisionDetection
CollisionResponse
RockGeometry
MaterialPropertiesof Rock
Object Database
PositionOrientation
ContactInformation
ForceTorque
Rock
EURON Summer School 2003
Mapping Between Visual and Haptic Workspaces
3D modelof a rock
Haptic Workspace
Visual Workspace
T3= T1.T2
T1
T2
EURON Summer School 2003
Synchronization of Cursor Movements
HIP T2Display
Visual Cursor
HIP (T2)-1 CollisionDetection
CollisionResponse(T2)
FFNEW
EURON Summer School 2003
EURON Summer School 2003
EURON Summer School 2003
• 3D Registration: problems with ICP, global registration• 3D Integration: robustness, storage requirements• 3D Transmission: 3D geometry comp. vs 3D data comp.• More effective transmission of normals and colors• 3D Visual and Haptic Texturing• Image-Based rendering• Optimized computation (e.g. efficient data structures such as ADFs)• Missing link between image analysis and 3d modeling• More efficient graphical rendering (e.g. point-based rendering)• Missing link between real-time 3D modeling and rover navigation• Unified data structures for transmission of multi-modal data
Unsolved/Untouched Problems
On-
boar
dC
ompu
tati
on
Resources
EURON Summer School 2003Acknowledgements:
Supporting NASA Programs: IPN, ISE, CISMISS, USRP, SBIR, JPL/Caltech-UROP
JPLAndres Castano (acquisition, registration)Aaron Keily (encoding)Ed Chow, Jose Salcedo (autostereoscopic visualization)Larry Bergman (human-rover interactions)
Industry (Physical Optics Corporation)Steve Cupiac (autostereoscopic visualization)Andrew Kostrzewski, Kirill Kolesnikov (autostereoscopic display; hardware integration)
StudentsMitch Lum, UW (autostereoscopic and haptic visualization)Elaine Ou, Caltech (vision and touch)
UniversityProf. Marc Levoy, Stanford (3D range scans of “bunny”, Scanalyze registration software; personal communication)Prof. Brian Curless, UW (3D photography notes; public domain)Dr. Huges Hoppe, Microsoft (Ph.D. Thesis and 3D reconstruction code; public domain)
EURON Summer School 2003
0.60
1.20
1.80
2.40
3.00%
Mea
n E
rror
Rel
ativ
e to
BB
ox
Dia
gon
al o
f H
igh
Res
olu
tion
Mod
el
4 6 8
Number of Octree Layers
AveragedCenter
(857 pts) (4834 pts) (5823 pts)
High ResolutionModel (35947 pts)
3(215 pts)
5 7
EURON Summer School 2003
0.60
1.20
1.80
2.40
3.00
% M
ean
Err
or R
elat
ive
to B
Box
D
iago
nal
of
Hig
h R
esol
uti
on M
odel
4 6 8
Number of Octree Layers
Using Estimated NormalsUsing Computed Normals
(931 pts) (13156 pts) (35781 pts)
High ResolutionModel (35947 pts)
3(220 pts)
5 7
3.60
EURON Summer School 2003
Octrees for 3D Data Transmission: Encoding
0 1
2 3
4
56
3 bites/octant
000 0001 1010 2..111 7
8 layers = 28 X 28 X 28 cubesResolution = 1000 mm / 28 = ~ 4 mm !!!
a*22 + b*2 + c
abc
1m
1m
1m
Path to a leaf node: 3 4 1 7 0 3 3 2
Ref: Yemez and Schmitt, 1999
EURON Summer School 2003
Path to a leaf node: 3 4 1 7 0 3 3 2
Layer 1 … Layer 8
Octrees for Progressive Transmission
All data is transmitted at once (Maximum 8 layers):
28 X 28 X 28 cubes * 3 bites/cube * 1 byte/8 bits = ~ 6.3 MB !!
Progressive Transmission:
If we transmit the differencebetween layer 4 to 5 : ~ 10 KB ! (not even compressed)
EURON Summer School 2003
EURON Summer School 2003
A Simple 3D Example:
Outputv1x v1y v1zv2x v2y v2z…v10x v10y v10zn1x n1y n1zn2x n2y n2z…n10x n10y n10z
Input Data:
Voxelization
EURON Summer School 2003
2D:• Perspective • Occlusion• Lighting, shadows• Relative motion• Texture
Stereoscopic Visualization: Depth Perception
3D:• Binocular disparity • Accommodation• Convergence
Stereo Pairs
EURON Summer School 2003
Stereo Rendering
Incorrect ! Correct !