PSI - Issue 12

Sandro Barone et al. / Procedia Structural Integrity 12 (2018) 122–129 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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4

Image 0, Left

Image 0, Right

Stereo DIC

Target

grid L,0

grid R,0

Speckle pattern

Speckle pattern

Target

2D DIC

2D DIC

Image i , Left

Image i , Right

DIC not required

Target

grid L, i

grid R, i

Speckle pattern

Speckle pattern

Target

Fig. 1. Schematic representation of the use of 2D DIC for 3D shape reconstruction.

Exciter

Camera

Light source

Blade

Mirrors

Fig. 2. Experimental setup during the acquisition process of a target surface

3.2. System characterization

The described unconventional optical setup was characterized in terms of measurement noise and accuracy by acquiring a static planar surface with a speckle pattern sprayed on it. The proposed DIC strategy was adopted to solve the stereo matching problem. A point cloud corresponding to the acquired surface was then obtained by exploiting the stereo-triangulation principle. The point cloud was used to compute the best fit plane, obtaining a standard deviation of 0.028 mm. This was considered a well reasonable result, which is perfectly comparable with typical optical setups