Microsoft PowerPoint - (2012)AOI Lab

Materials taken from Prof. S. Seitz, Carnegie Mellon University,2001
AOI Lab
AOI Lab
AOI Lab
AOI Lab
AOI Lab
Stereo Detection
AOI Lab
AOI Lab
AOI Lab
AOI Lab
AOI Lab
AOI Lab
Materials taken from Prof. T. Kanade, Carnegie Mellon University,
(Template Matching)

(Correlation Measures)
,,,
i=012…M-1j=012…N-1 IT
Normalization



b
2b
3b
4b
5b
6b
7b
8b
i0 2
S S D ( x , )
note: d=BFMaterials taken from Prof. T. Kanade, Carnegie Mellon University, 1995
AOI Lab
Materials taken from Prof. T. Kanade, Carnegie Mellon University, 1995
AOI Lab
Materials taken from Prof. T. Kanade, Carnegie Mellon University, 1995
AOI Lab
( ( ) ( ))I x j I x B F ji j W
i0 2
Materials taken from Prof. T. Kanade, Carnegie Mellon University, 1995
AOI Lab
Measurement Variance
Materials taken from Prof. T. Kanade, Carnegie Mellon University, 1995
Materials taken from Prof. T. Kanade, Carnegie Mellon University, 1995
AOI Lab
AOI Lab
Transform the extracted characteristic point from distorted image frame to undistorted image
frames
Calculate SSD and SSSD
Search for the minimal SSSD in order to decide the inverse distance
Calculate the depth
AOI Lab
Measured Depth (mm)
AOI Lab
AOI Lab
1. Laser triangulation principle 2. Mapping method 3. Binary encoding method
Active 3-D Vision Methods
Scattering principle
Light reflection model
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The reflected color of the measured surface can be roughly described by considering the coefficients of ambient and diffuse reflection as having red, green and blue components: Key factors:
1. view direction of CCD.
2. incident direction of light.
3. coefficient of specular reflection.
4. coefficient of diffuse reflection.
5. surface properties
Laser triangulation principle
(x,z) Plane:
41
CCD Image
42










3D space: (X,Y,Z)
CCD coordinate: (u,v)
Single laser-line projection with 2 CCDs
Laser Line Projection CCD images in left and right camera
Source from Prof. Chang 45
3D mapping from two images
3-D mapping from two image coordinates: 3D coordinate:(X,Y,X)
Left CCD image:(uL,vL)
Right CCD image:(uR,vR)
47
48





















3D coordinate:(X,Y,X)
Source from Prof. Chang 50
Line laser scanning method
51
52
Source from Dr.
Example of structured light projection on measured objects
Source from Dr.
Hardware setup of a micro- scale 3-D vision system
Source from Prof. Chang
59
60
3D point clouds 3D model using color shadowing
61
Tilting rotation table for scanning single tooth
62
Source from Prof. Chang64
for single laser line projection with single
CCD.
for single laser line projection with double
CCDs. 65
66
Fringe recognition problem
AOI Lab
way.
coded or phases shift fringes patterns. Gray codes binary images
use multiple frames with increased resolution (bits) to encode a
pixel on the CCD with its corresponding range.
• Sub-pixel resolution is obtained by detecting the edge
transitions in the highest resolution image.
Dealing With Range (or Phase Shift) Ambiguities
Spatial recoding method
Optical
grating
1 1 1 1 0 0 0 0
1 1 0 0 1 1 0 0
1 0 1 0 1 0 1 0 7 6 5 4 3 2 1 0
Fringe A
Fringe B
Fringe C
Source from Prof. Chang 71
• Binary encoding methods are today popular because of the availability of low cost projectors and a full 3D volume can be acquired quickly in just a few video frames. • The use of incoherent light reduces speckle noise associated with laser and consequently provides better surface smoothness. • The depth of view is smaller when compared to laser strip scanners and absolute accuracy for an equivalent 3-D volume (not only on the surface) will be relatively smaller than their laser counterparts.
White-light Binary encoding methods
4 5
P
AOI Lab
74
X
Image bundle Object with reference points
Z
Y
Camera
Fringe Projection System
76
AOI Lab
AOI Lab
Fringe pattern
Measuring Interior Door
Point cloud CAD-model
Measuring Interior Door
82
83
projection plane equation.
3. Dr. , AOI, .