Wyniki wyszukiwania - BazTech

1

Adaptive lighting for inhomogeneous reflectivity compensation in applications for 3D shape measurements

Casavola Caterina, Pappalettera Giovanni

Optica Applicata

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2019

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Vol. 49, nr 1

89--99

EN

Surface 3D reconstruction is a topic of great relevance and it has a wide range of applications in many fields such as mechanics, bioengineering and arts. Nowadays optical systems for 3D contouring such as those based on structured light projection are becoming more and more widespread. The possibility to get shape information without any contact with the object, in fact, is a great advantage in some fields such as, for example, cultural heritage. For this class of objects, however, the issue connected with inhomogeneous reflectivity must be taken into account. Due to the different level of reflectivity, in different areas of the object, it comes out that the contrast of the projected pattern changes and, as a direct consequence, the achievable accuracy can change from part to part. In this paper, a study on the possibility to implement an adaptive lighting algorithm is performed allowing to adapt illumination in order to compensate the local inhomogeneities in terms of surface reflectivity.

2

Surface Roughness Assessment of Woven Fabrics Using Fringe Projection Moiré Techniques

Ezazshahabi N., Tehran M. A., Latifi M., Madanipour K.

Fibres & Textiles in Eastern Europe

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2015

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Vol. 23, no. 3 (111)

76--84

EN

In this paper, a new approach is proposed for characterizing the surface roughness of woven fabrics. This approach is based on the fringe projection moiré techniques and analysis of the moiré pattern, which is caused by the interaction between the Ronchi grating and the periodic structure of a woven fabric. In this study, an image processing procedure was employed and a new parameter called the “roughness index” was defined for quantifying the surface roughness. The results obtained from the moiré technique were validated by a set of pair-comparison subjective tests. The proper correlation, with an average R-squared value of 0.9087, between subjective and objective tests confirmed the accuracy, correctness and efficiency of the new method. Statistical analysis of the roughness results clarified that the effect of fabric structural parameters such as the weave structure and weft density is significant in the confidence range of 95%.

PL

W pracy zaproponowano nową metodę charakteryzacji szorstkości powierzchni tkanin. Jest ona oparta na projekcji zagnieceń techniką Moiré i analizy otrzymanych wzorów uzyskanych poprzez interakcje pomiędzy siatką Ronchiego i okresową strukturą tkaniny. Opracowano procedurę analizy obrazu i zdefiniowano nowy parametr nazwany‚”indeksem szorstkości” dla ilościowej oceny szorstkości powierzchni. Wyniki otrzymane za pomocą techniki Moiré porównywano z wynikami subiektywnych testów. Uzyskano korelację na poziomie R2 = 0,9087 pomiędzy testami subiektywnym i obiektywnymi, co potwierdza prawidłowość zaproponowanej metody. Statystyczna analiza wyników wykazała, że efekt struktury tkaniny, jak rodzaj splotu i gęstość wątku jest istotna na poziomie 95%.

3

Optical inspection of formed sheet metal parts applying fringe projection systems and virtual fixation

Weckenmann A., Weickmann J.

Metrology and Measurement Systems

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2006

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Vol. 13, nr 4

321-334

EN

Modern forming technology allows the production of highly sophisticated free form sheet metal components, which are subject to a reversible geometrical deformation caused by residual stress, gravity or variations of the material. This distortion is usually removed during assembly and therefore the part's tolerated parameters have to be inspected in fixed state, which simulates assembly conditions. Today this time-consuming work is done on CMMs (Coordinate measuring machines). Using fast optical measuring systems and virtual fixation, this process chain can be dramatically shortened and in-line measurement seems to be possible in future. Virtual fixation means that at first a workpiece is measured in distorted state without fixation and afterwards the shape in assembled state is simulated by FEM analysis. Thus, workpieces can be inspected with significantly reduced effort.