Browsing by Subject "Stereovision"
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Item Evaluating fabric pilling/wrinkling appearance using 3D images(2013-12) Ouyang, Wenbin, active 2013; Xu, BugaoFabric appearance is usually the highest priority consideration for consumers. Pilling and wrinkling are two major factors which cause the fabric to have a worse appearance after a certain service period. In order to prevent more piling and wrinkling, a fabric pilling and wrinkling severity evaluation is very important. Traditional visual examination needs at least three trained experts to judge each sample, which is both subjective and time-consuming. Objective, high efficiency, and automatic pilling and wrinkling evaluation based on computer processing techniques are now being developed quickly. In this study, an integrated fabric pilling and wrinkling measurement system based on stereovision was developed. The hardware part of the system consists of a pair of consumer high resolution cameras and a mounting stage, which is affordable and portable in comparison with other 3D imaging systems. A novel pilling detection algorithm focusing on 3D image local information was proposed to extract three pilling features including pilling density, pilling average height, and pilling average size. The logistic regression classifier was applied for pilling severity classification because it showed a good accuracy with 80% on the 120 3D pilling images. A fast wrinkle detection algorithm with leveled 3D fabric surface was developed to measure wrinkle density, hardness, tip-angle, and roughness. According to these four wrinkling features, 180 3D wrinkling images were tested by the logistic regression classifier with an overall 74.4% accuracy in comparison with visual judging results. Both pilling and wrinkling results obtained from the proposed automatic 3D fabric pilling and wrinkling severity evaluation system were consistent with the subjective visual evaluation results. The system is ready for practical use.Item Fabric wrinkling and pilling evaluation by stereovision and three-dimensional surface characterization(2011-12) Yao, Ming, Ph. D.; Xu, Bugao; Chen, Jonathan Y.Wrinkling and pilling caused in wear and care procedures are vital performance characteristics of fabric. The advance of three-dimensional (3D) imaging techniques has made it possible to develop a convenient, reliable and low cost tool for automatic and efficient evaluation of fabric wrinkling and pilling. We suggest that 3D imaging and measurement system can provide a convenient, accommodating and comprehensive mean to fabric surface assessment. A 3D imaging system based on stereo vision technology is developed. To make it more affordable and portable, the system consists of a pair of consumer grade high resolution digital cameras with mounting hardware. The system is calibrated with classic camera calibration technique. The calibration procedure is relatively complicated, but there is no need to repeat frequently as long as the relative positions between cameras are not changed. In this system, image acquisition can be completed in less than one second. This efficient surface capturing feature is important for a large amount of measurement tasks. However, the computation in stereo vision is complex and intensive, thus it remains a challenge. A two-phase multi-resolution stereo matching algorithm is developed. In the first phase, a discrete disparity map is generated by block matching. In the second phase, local least-squares matching is performed in combination with global optimization within a regularization framework, so as to ensure both accuracy and reliability. To make the 3D imaging system ready for practical use, detection and measurement modules for wrinkling and pilling were developed to take advantage of the depth information in the 3D surface data. The practical feasibility of the 3D imaging system in fabric surface assessment was demonstrated in comparison with human visual ratings. The results showed agreement between the 3D automatic assessment and subjective visual assessment.