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Detekcija izbranih površinskih anomalij na odbojnih površinah z deflektometrijo
ID Žust, Lojze (Author), ID Kristan, Matej (Mentor) More about this mentor... This link opens in a new window

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Abstract
Diplomsko delo opisuje problem detekcije anomalij na reflektivnih površinah z uporabo deflektometrije. Predlagamo novo metodo za detekcijo anomalij, ki je sposobna hitre detekcije na podlagi zgolj ene slike opazovane površine. Klasične metode deflektometrije izdelajo 3D rekonstrukcijo opazovanega objekta, napake pa zaznajo z odstopanji pri primerjavi z referenčnim objektom brez defektov. Večina teh metod za delovanje potrebuje natančno kalibracijo sistema. Ker se metoda, ki jo predlagamo, uči na anotiranih primerih anomalij, pri inferenci ne potrebuje posebne kalibracije in referenčnih objektov. Detekcijo anomalij opišemo kot problem semantične segmentacije, ki za vsak piksel napove verjetnost anomalije. Za implementacijo semantične segmentacije uporabimo konvolucijske nevronske mreže. Predlagamo tudi robusten postopek za lokalizacijo detekcij iz segmentacijske maske, ki je sposoben zaznati tudi delno prekrivajoče anomalije. S preliminarno analizo in eksperimentalno evalvacijo utemeljimo izbiro arhitekture ter hiperparametrov modela. Razvito metodo učimo in evalviramo na problemu detekcije udrtin v strehi avtomobila, kjer pokazažemo bistvene izboljšave v primerjavi z osnovno metodo. Naša metoda je na testih dosegla natančnost 0.88, priklic 0.88 in F-mero 0.88, kar predstavlja skoraj 50% izboljšavo v primerjavi z osnovno metodo.

Language:Slovenian
Keywords:konvolucija, nevronske mreže, deflektometrija, semantična segmentacija, strojno učenje
Work type:Bachelor thesis/paper
Typology:2.11 - Undergraduate Thesis
Organization:FRI - Faculty of Computer and Information Science
Year:2018
PID:20.500.12556/RUL-125593 This link opens in a new window
COBISS.SI-ID:1537832643 This link opens in a new window
Publication date in RUL:26.03.2021
Views:1624
Downloads:229
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Secondary language

Language:English
Title:Deflectometry-based detection of specific reflective surface anomalies
Abstract:
In this thesis we propose a new deflectometry-based anomaly detection approach applicable to reflective surfaces. Classic deflectometry methods detect surface anomalies by performing partial 3D surface reconstruction and differencing it with a pre-recorded reference model of the observed object. Most of these methods require projection of several patterns and require accurate calibration between the pattern projector, camera and the inspected object. In contrast, our anomaly detection approach is defined as a semantic segmentation problem and performs pixel-wise anomaly classification. We utilize the power of deep models for this purpose. Since the proposed method can be trained on annotated anomaly examples, reference objects are not needed, the detection is fast, requires only a single pattern projection and does not require accurate calibration. Furthermore, a robust method for anomaly localization from the segmentation mask is proposed, capable of extracting partially overlapping detections. Preliminary analysis and experimental evaluation were performed to justify the architecture and hyper-parameters of our deep semantic segmentation model. The final model was trained and evaluated on the problem of dent detection in car roofs, where a significant improvement over the base method has been shown. Our model achieves a precision of 0.88, recall of 0.88 and F-score of 0.88 on test data, which represents a nearly 50% improvement over the base method.

Keywords:convolution, neural networks, deflectometry, semantic segmentation, machine learning

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