| Records |
| Author |
Juan Ramon Terven Salinas; Joaquin Salas; Bogdan Raducanu |
| Title |
New Opportunities for Computer Vision-Based Assistive Technology Systems for the Visually Impaired |
Type |
Journal Article |
| Year |
2014 |
Publication |
Computer |
Abbreviated Journal |
COMP |
Volume  |
47 |
Issue |
4 |
Pages |
52-58 |
| Keywords |
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| Abstract |
Computing advances and increased smartphone use gives technology system designers greater flexibility in exploiting computer vision to support visually impaired users. Understanding these users' needs will certainly provide insight for the development of improved usability of computing devices. |
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Edition |
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| ISSN |
0018-9162 |
ISBN |
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Medium |
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Conference |
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| Notes |
LAMP; |
Approved |
no |
| Call Number |
Admin @ si @ TSR2014a |
Serial |
2317 |
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| Author |
Bogdan Raducanu; Fadi Dornaika |
| Title |
Embedding new observations via sparse-coding for non-linear manifold learning |
Type |
Journal Article |
| Year |
2014 |
Publication |
Pattern Recognition |
Abbreviated Journal |
PR |
| Volume |
47 |
Issue |
1 |
Pages |
480-492 |
| Keywords |
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| Abstract |
Non-linear dimensionality reduction techniques are affected by two critical aspects: (i) the design of the adjacency graphs, and (ii) the embedding of new test data-the out-of-sample problem. For the first aspect, the proposed solutions, in general, were heuristically driven. For the second aspect, the difficulty resides in finding an accurate mapping that transfers unseen data samples into an existing manifold. Past works addressing these two aspects were heavily parametric in the sense that the optimal performance is only achieved for a suitable parameter choice that should be known in advance. In this paper, we demonstrate that the sparse representation theory not only serves for automatic graph construction as shown in recent works, but also represents an accurate alternative for out-of-sample embedding. Considering for a case study the Laplacian Eigenmaps, we applied our method to the face recognition problem. To evaluate the effectiveness of the proposed out-of-sample embedding, experiments are conducted using the K-nearest neighbor (KNN) and Kernel Support Vector Machines (KSVM) classifiers on six public face datasets. The experimental results show that the proposed model is able to achieve high categorization effectiveness as well as high consistency with non-linear embeddings/manifolds obtained in batch modes. |
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| Notes |
LAMP; |
Approved |
no |
| Call Number |
Admin @ si @ RaD2013b |
Serial |
2316 |
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| Author |
Cesar Isaza; Joaquin Salas; Bogdan Raducanu |
| Title |
Rendering ground truth data sets to detect shadows cast by static objects in outdoors |
Type |
Journal Article |
| Year |
2014 |
Publication |
Multimedia Tools and Applications |
Abbreviated Journal |
MTAP |
| Volume |
70 |
Issue |
1 |
Pages |
557-571 |
| Keywords |
Synthetic ground truth data set; Sun position; Shadow detection; Static objects shadow detection |
| Abstract |
In our work, we are particularly interested in studying the shadows cast by static objects in outdoor environments, during daytime. To assess the accuracy of a shadow detection algorithm, we need ground truth information. The collection of such information is a very tedious task because it is a process that requires manual annotation. To overcome this severe limitation, we propose in this paper a methodology to automatically render ground truth using a virtual environment. To increase the degree of realism and usefulness of the simulated environment, we incorporate in the scenario the precise longitude, latitude and elevation of the actual location of the object, as well as the sun’s position for a given time and day. To evaluate our method, we consider a qualitative and a quantitative comparison. In the quantitative one, we analyze the shadow cast by a real object in a particular geographical location and its corresponding rendered model. To evaluate qualitatively the methodology, we use some ground truth images obtained both manually and automatically. |
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Springer US |
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Edition |
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| ISSN |
1380-7501 |
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| Notes |
LAMP; |
Approved |
no |
| Call Number |
Admin @ si @ ISR2014 |
Serial |
2229 |
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| Author |
Oscar Argudo; Marc Comino; Antonio Chica; Carlos Andujar; Felipe Lumbreras |
| Title |
Segmentation of aerial images for plausible detail synthesis |
Type |
Journal Article |
| Year |
2018 |
Publication |
Computers & Graphics |
Abbreviated Journal |
CG |
| Volume |
71 |
Issue |
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Pages |
23-34 |
| Keywords |
Terrain editing; Detail synthesis; Vegetation synthesis; Terrain rendering; Image segmentation |
| Abstract |
The visual enrichment of digital terrain models with plausible synthetic detail requires the segmentation of aerial images into a suitable collection of categories. In this paper we present a complete pipeline for segmenting high-resolution aerial images into a user-defined set of categories distinguishing e.g. terrain, sand, snow, water, and different types of vegetation. This segmentation-for-synthesis problem implies that per-pixel categories must be established according to the algorithms chosen for rendering the synthetic detail. This precludes the definition of a universal set of labels and hinders the construction of large training sets. Since artists might choose to add new categories on the fly, the whole pipeline must be robust against unbalanced datasets, and fast on both training and inference. Under these constraints, we analyze the contribution of common per-pixel descriptors, and compare the performance of state-of-the-art supervised learning algorithms. We report the findings of two user studies. The first one was conducted to analyze human accuracy when manually labeling aerial images. The second user study compares detailed terrains built using different segmentation strategies, including official land cover maps. These studies demonstrate that our approach can be used to turn digital elevation models into fully-featured, detailed terrains with minimal authoring efforts. |
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Edition |
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| ISSN |
0097-8493 |
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| Notes |
MSIAU; 600.086; 600.118 |
Approved |
no |
| Call Number |
Admin @ si @ ACC2018 |
Serial |
3147 |
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| Author |
Carola Figueroa Flores; Abel Gonzalez-Garcia; Joost Van de Weijer; Bogdan Raducanu |
| Title |
Saliency for fine-grained object recognition in domains with scarce training data |
Type |
Journal Article |
| Year |
2019 |
Publication |
Pattern Recognition |
Abbreviated Journal |
PR |
| Volume |
94 |
Issue |
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Pages |
62-73 |
| Keywords |
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| Abstract |
This paper investigates the role of saliency to improve the classification accuracy of a Convolutional Neural Network (CNN) for the case when scarce training data is available. Our approach consists in adding a saliency branch to an existing CNN architecture which is used to modulate the standard bottom-up visual features from the original image input, acting as an attentional mechanism that guides the feature extraction process. The main aim of the proposed approach is to enable the effective training of a fine-grained recognition model with limited training samples and to improve the performance on the task, thereby alleviating the need to annotate a large dataset. The vast majority of saliency methods are evaluated on their ability to generate saliency maps, and not on their functionality in a complete vision pipeline. Our proposed pipeline allows to evaluate saliency methods for the high-level task of object recognition. We perform extensive experiments on various fine-grained datasets (Flowers, Birds, Cars, and Dogs) under different conditions and show that saliency can considerably improve the network’s performance, especially for the case of scarce training data. Furthermore, our experiments show that saliency methods that obtain improved saliency maps (as measured by traditional saliency benchmarks) also translate to saliency methods that yield improved performance gains when applied in an object recognition pipeline. |
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| Notes |
LAMP; 600.109; 600.141; 600.120 |
Approved |
no |
| Call Number |
Admin @ si @ FGW2019 |
Serial |
3264 |
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| Author |
Juan Ramon Terven Salinas; Bogdan Raducanu; Maria Elena Meza-de-Luna; Joaquin Salas |
| Title |
Head-gestures mirroring detection in dyadic social linteractions with computer vision-based wearable devices |
Type |
Journal Article |
| Year |
2016 |
Publication |
Neurocomputing |
Abbreviated Journal |
NEUCOM |
| Volume |
175 |
Issue |
B |
Pages |
866–876 |
| Keywords |
Head gestures recognition; Mirroring detection; Dyadic social interaction analysis; Wearable devices |
| Abstract |
During face-to-face human interaction, nonverbal communication plays a fundamental role. A relevant aspect that takes part during social interactions is represented by mirroring, in which a person tends to mimic the non-verbal behavior (head and body gestures, vocal prosody, etc.) of the counterpart. In this paper, we introduce a computer vision-based system to detect mirroring in dyadic social interactions with the use of a wearable platform. In our context, mirroring is inferred as simultaneous head noddings displayed by the interlocutors. Our approach consists of the following steps: (1) facial features extraction; (2) facial features stabilization; (3) head nodding recognition; and (4) mirroring detection. Our system achieves a mirroring detection accuracy of 72% on a custom mirroring dataset. |
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| Notes |
LAMP; 600.072; 600.068; |
Approved |
no |
| Call Number |
Admin @ si @ TRM2016 |
Serial |
2721 |
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| Author |
Juan Ramon Terven Salinas; Joaquin Salas; Bogdan Raducanu |
| Title |
Robust Head Gestures Recognition for Assistive Technology |
Type |
Book Chapter |
| Year |
2014 |
Publication |
Pattern Recognition |
Abbreviated Journal |
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| Volume |
8495 |
Issue |
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Pages |
152-161 |
| Keywords |
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| Abstract |
This paper presents a system capable of recognizing six head gestures: nodding, shaking, turning right, turning left, looking up, and looking down. The main difference of our system compared to other methods is that the Hidden Markov Models presented in this paper, are fully connected and consider all possible states in any given order, providing the following advantages to the system: (1) allows unconstrained movement of the head and (2) it can be easily integrated into a wearable device (e.g. glasses, neck-hung devices), in which case it can robustly recognize gestures in the presence of ego-motion. Experimental results show that this approach outperforms common methods that use restricted HMMs for each gesture. |
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Springer International Publishing |
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LNCS |
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0302-9743 |
ISBN |
978-3-319-07490-0 |
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LAMP; |
Approved |
no |
| Call Number |
Admin @ si @ TSR2014b |
Serial |
2505 |
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| Author |
Gemma Rotger; Francesc Moreno-Noguer; Felipe Lumbreras; Antonio Agudo |
| Title |
Single view facial hair 3D reconstruction |
Type |
Conference Article |
| Year |
2019 |
Publication |
9th Iberian Conference on Pattern Recognition and Image Analysis |
Abbreviated Journal |
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| Volume |
11867 |
Issue |
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Pages |
423-436 |
| Keywords |
3D Vision; Shape Reconstruction; Facial Hair Modeling |
| Abstract |
n this work, we introduce a novel energy-based framework that addresses the challenging problem of 3D reconstruction of facial hair from a single RGB image. To this end, we identify hair pixels over the image via texture analysis and then determine individual hair fibers that are modeled by means of a parametric hair model based on 3D helixes. We propose to minimize an energy composed of several terms, in order to adapt the hair parameters that better fit the image detections. The final hairs respond to the resulting fibers after a post-processing step where we encourage further realism. The resulting approach generates realistic facial hair fibers from solely an RGB image without assuming any training data nor user interaction. We provide an experimental evaluation on real-world pictures where several facial hair styles and image conditions are observed, showing consistent results and establishing a comparison with respect to competing approaches. |
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Madrid; July 2019 |
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IbPRIA |
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MSIAU; 600.086; 600.130; 600.122 |
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no |
| Call Number |
Admin @ si @ |
Serial |
3707 |
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| Author |
Javad Zolfaghari Bengar; Bogdan Raducanu; Joost Van de Weijer |
| Title |
When Deep Learners Change Their Mind: Learning Dynamics for Active Learning |
Type |
Conference Article |
| Year |
2021 |
Publication |
19th International Conference on Computer Analysis of Images and Patterns |
Abbreviated Journal |
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| Volume |
13052 |
Issue |
1 |
Pages |
403-413 |
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| Abstract |
Active learning aims to select samples to be annotated that yield the largest performance improvement for the learning algorithm. Many methods approach this problem by measuring the informativeness of samples and do this based on the certainty of the network predictions for samples. However, it is well-known that neural networks are overly confident about their prediction and are therefore an untrustworthy source to assess sample informativeness. In this paper, we propose a new informativeness-based active learning method. Our measure is derived from the learning dynamics of a neural network. More precisely we track the label assignment of the unlabeled data pool during the training of the algorithm. We capture the learning dynamics with a metric called label-dispersion, which is low when the network consistently assigns the same label to the sample during the training of the network and high when the assigned label changes frequently. We show that label-dispersion is a promising predictor of the uncertainty of the network, and show on two benchmark datasets that an active learning algorithm based on label-dispersion obtains excellent results. |
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September 2021 |
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CAIP |
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LAMP; |
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no |
| Call Number |
Admin @ si @ ZRV2021 |
Serial |
3673 |
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