StudentsStudents::MarcoMarco TomasiniTomasini Michele ManciniMichele Mancini

CourseCourse: Optical : Optical MeasurementsMeasurements 20072007

Reverse engineering of a free-form objectby using the projection of structured light

Objectives• Use of OPL-3d to produce the 3D mesh of

a small car• Use PolyWorks to align, create and edit

the model• Steps:

– Calibration of OPL-3D– Acquisition and alignment of the views– Model creation– Model editing– Topological control of the model for RP.

• Optical layout– L: standoff– D: baseline– Zrange: measurement range– FOV: field of view

Active stereo vision

2

The sensor

• Calibration:– Camera parameters– Projection parameters– Need of a calibration master

4

• Compensation of both radial and tangential distortion

Calibration software

markers

5

Multiview acquisition

• Need of markers to perform the alignment• Acquisition of multiple views to full cover

the surface

6

Fringe projection

• Gray code phase shiftcombination

10

Alignment

11

• Iterative process: need a compromise betweenadherence of the reconstruction and file dimension

Performance of the alignment

N° triangles : 323101

Surface sampling 0,29

15

Mesh creation

16

Mesh 1

N° triangles : 245748

Sampling 0,4

17

Mesh 2

18

Mesh 2

N° triangles : 201105

Sampling 0,5

19

Mesh 3

20

Mesh 3

Before

22

Editing: fill holes

after

23

Editing: fill holes

Before

after

25

• Shadows areas result in lost information

Surface reconstruction

before after

26

Manual editing

before after

32

The final model