Accurate fringe analysis Accurate fringe analysis in a 3D range sensor in a 3D range sensor for the fast measurement for the fast measurement of shapes of shapes G. Sansoni, G. Sansoni, F. Docchio, E. Redaelli F. Docchio, E. Redaelli Laboratory of Optoelectronics Laboratory of Optoelectronics University of Brescia, Italy University of Brescia, Italy
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Accurate fringe analysis in a 3D range sensor for the fast measurement of shapes G. Sansoni, F. Docchio, E. Redaelli Laboratory of Optoelectronics University.
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Accurate fringe analysisAccurate fringe analysis in a 3D range sensor in a 3D range sensor
for the fast measurement for the fast measurement of shapes of shapes
G. Sansoni, G. Sansoni, F. Docchio, E. RedaelliF. Docchio, E. Redaelli
Laboratory of OptoelectronicsLaboratory of Optoelectronics
University of Brescia, ItalyUniversity of Brescia, Italy
22
Context of the workContext of the work
National Italian Project: Low-cost 3D imaging and modeling automatic system (LIMA3D)
BRESCIA
MILANO
GENOVA
VERONA
FIRENZE
PALERMO
BRESCIA
Laboratory of Optoelectronics
Design, development and metrological characterization of a low-cost optical digitizer based on the projection of
a single grating of non-coherent light
Field of View (FOV): up to 300X400mm2
Depth range: up to 100mm
Measurement uncertainty: 0.3mm
33
What the system is notWhat the system is not
• Optical active triangulation• Time-space coding of the meas. volume
Fringe projectorVideo camera
Assembly system
OPL-3D
44
Winged Victory
Sestertius
Ferrari 250 MM
55
What the system isWhat the system is
• Use of low-cost projection device
Slide projector Video beam
• Optical active triangulation
• Projection of a single pattern of light
• Time space coding of the scene
66
ji
Up
FW
FH
Projector
Video cameraS’(iS,jS)
Zg
Xg
YgOg
c c
c
c
O X
Y
Z
p
pX
OZ
Yp
p
Projection Label: LS
d L
S
S(iS, jS, LS)
LS
T
LT
T(iS, jS, LT)
S(XS, YS, ZS)
T(XT,YT, ZT)
Map of labelsj
i
Phase mapping
Camera-projector Calibration
Measurement principleMeasurement principle
77
Input GC(i,j)
Normalization
Gc(i,j)
-50
0
50
100
150
200
250
100 120 140 160 180 200
Pixel
Inte
nsi
ty
Phase mappingPhase mapping
GC,n(i,j)
Gc,n(i,j)
-150
-100
-50
0
50
100
150
200
100 120 140 160 180 200
Pixel
Inte
nsi
ty
GC,b(i,j)
Binarization Gc,b(i,j)
-150
-100
-50
0
50
100
150
100 120 140 160 180 200
Pixel
Inte
nsity
gf(i,j)gr(i,j)
Edge detector
gr(i,j), gf(i,j)
-150
-100
-50
0
50
100
150
100 120 140 160 180 200
Pixel
Inte
nsity
Rise Fall
gr,f(i,j) gf,f(i,j)
Low-pass filtering
gr,f(i,j), gf,f(i,j)
-300
-200
-100
0
100
200
300
100 120 140 160 180 200
Pixel
Inte
nsi
ty
Rise Fall
gr,n(i,j) gf,n(i,j)
Amplitude normalization
gr,n(i,j), gf,n(i,j)
-1,5
-1
-0,5
0
0,5
1
1,5
100 120 140 160 180 200
Pixel
Inte
nsi
ty
Rise Fall
W(i,j)
%
ATAN2
W(i,j)
-4
-3
-2
-1
0
1
2
3
4
100 120 140 160 180 200
Pixel
Rad
88
The phase unwrappingThe phase unwrapping
• Pure spatial approach• Spatio-temporal approach (optional)