Accurate fringe analysis in a 3D range sensor for the fast measurement of shapes G. Sansoni, F....

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)

99

Camera-Projector calibrationCamera-Projector calibration

1010

Sanyo PROxtraX LCD

Hitachi KP-D50 Color

The prototypeThe prototype

1111

Experimental results (1)Experimental results (1)

1212

Exprimental results (2)Exprimental results (2)

1313

Metrological characterizationMetrological characterization

1414

Metrological characterizationMetrological characterization

1515

ConclusionsConclusions

• Low-cost 3D system based on phase measurement

• Characterization of the measurement performance

• Experimentation with high resolution cameras• Experimentation with a 3CCD color camera