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Mohammad N. S. Jahromi, Pau Buch Cardona, Egils Avots, Kamal Nasrollahi, Sergio Escalera, Thomas B. Moeslund, et al. (2019). Privacy-Constrained Biometric System for Non-cooperative Users. ENTROPY - Entropy, 21(11), 1033.
Abstract: With the consolidation of the new data protection regulation paradigm for each individual within the European Union (EU), major biometric technologies are now confronted with many concerns related to user privacy in biometric deployments. When individual biometrics are disclosed, the sensitive information about his/her personal data such as financial or health are at high risk of being misused or compromised. This issue can be escalated considerably over scenarios of non-cooperative users, such as elderly people residing in care homes, with their inability to interact conveniently and securely with the biometric system. The primary goal of this study is to design a novel database to investigate the problem of automatic people recognition under privacy constraints. To do so, the collected data-set contains the subject’s hand and foot traits and excludes the face biometrics of individuals in order to protect their privacy. We carried out extensive simulations using different baseline methods, including deep learning. Simulation results show that, with the spatial features extracted from the subject sequence in both individual hand or foot videos, state-of-the-art deep models provide promising recognition performance.
Keywords: biometric recognition; multimodal-based human identification; privacy; deep learning
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Wenlong Deng, Yongli Mou, Takahiro Kashiwa, Sergio Escalera, Kohei Nagai, Kotaro Nakayama, et al. (2020). Vision based Pixel-level Bridge Structural Damage Detection Using a Link ASPP Network. AC - Automation in Construction, 110, 102973.
Abstract: Structural Health Monitoring (SHM) has greatly benefited from computer vision. Recently, deep learning approaches are widely used to accurately estimate the state of deterioration of infrastructure. In this work, we focus on the problem of bridge surface structural damage detection, such as delamination and rebar exposure. It is well known that the quality of a deep learning model is highly dependent on the quality of the training dataset. Bridge damage detection, our application domain, has the following main challenges: (i) labeling the damages requires knowledgeable civil engineering professionals, which makes it difficult to collect a large annotated dataset; (ii) the damage area could be very small, whereas the background area is large, which creates an unbalanced training environment; (iii) due to the difficulty to exactly determine the extension of the damage, there is often a variation among different labelers who perform pixel-wise labeling. In this paper, we propose a novel model for bridge structural damage detection to address the first two challenges. This paper follows the idea of an atrous spatial pyramid pooling (ASPP) module that is designed as a novel network for bridge damage detection. Further, we introduce the weight balanced Intersection over Union (IoU) loss function to achieve accurate segmentation on a highly unbalanced small dataset. The experimental results show that (i) the IoU loss function improves the overall performance of damage detection, as compared to cross entropy loss or focal loss, and (ii) the proposed model has a better ability to detect a minority class than other light segmentation networks.
Keywords: Semantic image segmentation; Deep learning
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Juan Jose Rubio, Takahiro Kashiwa, Teera Laiteerapong, Wenlong Deng, Kohei Nagai, Sergio Escalera, et al. (2019). Multi-class structural damage segmentation using fully convolutional networks. COMPUTIND - Computers in Industry, 112, 103121.
Abstract: Structural Health Monitoring (SHM) has benefited from computer vision and more recently, Deep Learning approaches, to accurately estimate the state of deterioration of infrastructure. In our work, we test Fully Convolutional Networks (FCNs) with a dataset of deck areas of bridges for damage segmentation. We create a dataset for delamination and rebar exposure that has been collected from inspection records of bridges in Niigata Prefecture, Japan. The dataset consists of 734 images with three labels per image, which makes it the largest dataset of images of bridge deck damage. This data allows us to estimate the performance of our method based on regions of agreement, which emulates the uncertainty of in-field inspections. We demonstrate the practicality of FCNs to perform automated semantic segmentation of surface damages. Our model achieves a mean accuracy of 89.7% for delamination and 78.4% for rebar exposure, and a weighted F1 score of 81.9%.
Keywords: Bridge damage detection; Deep learning; Semantic segmentation
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Egils Avots, Meysam Madadi, Sergio Escalera, Jordi Gonzalez, Xavier Baro, Paul Pallin, et al. (2019). From 2D to 3D geodesic-based garment matching. MTAP - Multimedia Tools and Applications, 78(18), 25829–25853.
Abstract: A new approach for 2D to 3D garment retexturing is proposed based on Gaussian mixture models and thin plate splines (TPS). An automatically segmented garment of an individual is matched to a new source garment and rendered, resulting in augmented images in which the target garment has been retextured using the texture of the source garment. We divide the problem into garment boundary matching based on Gaussian mixture models and then interpolate inner points using surface topology extracted through geodesic paths, which leads to a more realistic result than standard approaches. We evaluated and compared our system quantitatively by root mean square error (RMS) and qualitatively using the mean opinion score (MOS), showing the benefits of the proposed methodology on our gathered dataset.
Keywords: Shape matching; Geodesic distance; Texture mapping; RGBD image processing; Gaussian mixture model
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Andre Litvin, Kamal Nasrollahi, Sergio Escalera, Cagri Ozcinar, Thomas B. Moeslund, & Gholamreza Anbarjafari. (2019). A Novel Deep Network Architecture for Reconstructing RGB Facial Images from Thermal for Face Recognition. MTAP - Multimedia Tools and Applications, 78(18), 25259–25271.
Abstract: This work proposes a fully convolutional network architecture for RGB face image generation from a given input thermal face image to be applied in face recognition scenarios. The proposed method is based on the FusionNet architecture and increases robustness against overfitting using dropout after bridge connections, randomised leaky ReLUs (RReLUs), and orthogonal regularization. Furthermore, we propose to use a decoding block with resize convolution instead of transposed convolution to improve final RGB face image generation. To validate our proposed network architecture, we train a face classifier and compare its face recognition rate on the reconstructed RGB images from the proposed architecture, to those when reconstructing images with the original FusionNet, as well as when using the original RGB images. As a result, we are introducing a new architecture which leads to a more accurate network.
Keywords: Fully convolutional networks; FusionNet; Thermal imaging; Face recognition
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