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Author | Anjan Dutta | ||||
Title | Inexact Subgraph Matching Applied to Symbol Spotting in Graphical Documents | Type | Book Whole | ||
Year | 2014 | Publication | PhD Thesis, Universitat Autonoma de Barcelona-CVC | Abbreviated Journal | |
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Abstract | There is a resurgence in the use of structural approaches in the usual object recognition and retrieval problem. Graph theory, in particular, graph matching plays a relevant role in that. Specifically, the detection of an object (or a part of that) in an image in terms of structural features can be formulated as a subgraph matching. Subgraph matching is a challenging task. Specially due to the presence of outliers most of the graph matching algorithms do not perform well in subgraph matching scenario. Also exact subgraph isomorphism has proven to be an NP-complete problem. So naturally, in graph matching community, there are lot of efforts addressing the problem of subgraph matching within suboptimal bound. Most of them work with approximate algorithms that try to get an inexact solution in estimated way. In addition, usual recognition must cope with distortion. Inexact graph matching consists in finding the best isomorphism under a similarity measure. Theoretically this thesis proposes algorithms for solving subgraph matching in an approximate and inexact way.
We consider the symbol spotting problem on graphical documents or line drawings from application point of view. This is a well known problem in the graphics recognition community. It can be further applied for indexing and classification of documents based on their contents. The structural nature of this kind of documents easily motivates one for giving a graph based representation. So the symbol spotting problem on graphical documents can be considered as a subgraph matching problem. The main challenges in this application domain is the noise and distortions that might come during the usage, digitalization and raster to vector conversion of those documents. Apart from that computer vision nowadays is not any more confined within a limited number of images. So dealing a huge number of images with graph based method is a further challenge. In this thesis, on one hand, we have worked on efficient and robust graph representation to cope with the noise and distortions coming from documents. On the other hand, we have worked on different graph based methods and framework to solve the subgraph matching problem in a better approximated way, which can also deal with considerable number of images. Firstly, we propose a symbol spotting method by hashing serialized subgraphs. Graph serialization allows to create factorized substructures such as graph paths, which can be organized in hash tables depending on the structural similarities of the serialized subgraphs. The involvement of hashing techniques helps to reduce the search space substantially and speeds up the spotting procedure. Secondly, we introduce contextual similarities based on the walk based propagation on tensor product graph. These contextual similarities involve higher order information and more reliable than pairwise similarities. We use these higher order similarities to formulate subgraph matching as a node and edge selection problem in the tensor product graph. Thirdly, we propose near convex grouping to form near convex region adjacency graph which eliminates the limitations of traditional region adjacency graph representation for graphic recognition. Fourthly, we propose a hierarchical graph representation by simplifying/correcting the structural errors to create a hierarchical graph of the base graph. Later these hierarchical graph structures are matched with some graph matching methods. Apart from that, in this thesis we have provided an overall experimental comparison of all the methods and some of the state-of-the-art methods. Furthermore, some dataset models have also been proposed. |
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Corporate Author | Thesis | Ph.D. thesis | |||
Publisher | Ediciones Graficas Rey | Place of Publication | Editor | Josep Llados;Umapada Pal | |
Language | Summary Language | Original Title | |||
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ISSN | ISBN | 978-84-940902-4-0 | Medium | ||
Area | Expedition | Conference | |||
Notes | DAG; 600.077 | Approved | no | ||
Call Number | Admin @ si @ Dut2014 | Serial | 2465 | ||
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Author | Aniol Lidon; Xavier Giro; Marc Bolaños; Petia Radeva; Markus Seidl; Matthias Zeppelzauer | ||||
Title | UPC-UB-STP @ MediaEval 2015 diversity task: iterative reranking of relevant images | Type | Conference Article | ||
Year | 2015 | Publication | 2015 MediaEval Retrieving Diverse Images Task | Abbreviated Journal | |
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Abstract | This paper presents the results of the UPC-UB-STP team in the 2015 MediaEval Retrieving Diverse Images Task. The goal of the challenge is to provide a ranked list of Flickr photos for a predefined set of queries. Our approach firstly generates a ranking of images based on a query-independent estimation of its relevance. Only top results are kept and iteratively re-ranked based on their intra-similarity to introduce diversity. | ||||
Address | Wurzen; Germany; September 2015 | ||||
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Area | Expedition | Conference | MediaEval | ||
Notes | MILAB | Approved | no | ||
Call Number | Admin @ si @LGB2016 | Serial | 2793 | ||
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Author | Aniol Lidon; Marc Bolaños; Mariella Dimiccoli; Petia Radeva; Maite Garolera; Xavier Giro | ||||
Title | Semantic Summarization of Egocentric Photo-Stream Events | Type | Conference Article | ||
Year | 2017 | Publication | 2nd Workshop on Lifelogging Tools and Applications | Abbreviated Journal | |
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Address | San Francisco; USA; October 2017 | ||||
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ISSN | ISBN | 978-1-4503-5503-2 | Medium | ||
Area | Expedition | Conference | ACMW (LTA) | ||
Notes | MILAB; no proj | Approved | no | ||
Call Number | Admin @ si @ LBD2017 | Serial | 3024 | ||
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Author | Anguelos Nicolaou; Sounak Dey; V.Christlein; A.Maier; Dimosthenis Karatzas | ||||
Title | Non-deterministic Behavior of Ranking-based Metrics when Evaluating Embeddings | Type | Conference Article | ||
Year | 2018 | Publication | International Workshop on Reproducible Research in Pattern Recognition | Abbreviated Journal | |
Volume | 11455 | Issue | Pages | 71-82 | |
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Abstract | Embedding data into vector spaces is a very popular strategy of pattern recognition methods. When distances between embeddings are quantized, performance metrics become ambiguous. In this paper, we present an analysis of the ambiguity quantized distances introduce and provide bounds on the effect. We demonstrate that it can have a measurable effect in empirical data in state-of-the-art systems. We also approach the phenomenon from a computer security perspective and demonstrate how someone being evaluated by a third party can exploit this ambiguity and greatly outperform a random predictor without even access to the input data. We also suggest a simple solution making the performance metrics, which rely on ranking, totally deterministic and impervious to such exploits. | ||||
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Language | Summary Language | Original Title | |||
Series Editor | Series Title | Abbreviated Series Title | LNCS | ||
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ISSN | ISBN | Medium | |||
Area | Expedition | Conference | |||
Notes | DAG; 600.121; 600.129 | Approved | no | ||
Call Number | Admin @ si @ NDC2018 | Serial | 3178 | ||
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Author | Anguelos Nicolaou; Andrew Bagdanov; Marcus Liwicki; Dimosthenis Karatzas | ||||
Title | Sparse Radial Sampling LBP for Writer Identification | Type | Conference Article | ||
Year | 2015 | Publication | 13th International Conference on Document Analysis and Recognition ICDAR2015 | Abbreviated Journal | |
Volume | Issue | Pages | 716-720 | ||
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Abstract | In this paper we present the use of Sparse Radial Sampling Local Binary Patterns, a variant of Local Binary Patterns (LBP) for text-as-texture classification. By adapting and extending the standard LBP operator to the particularities of text we get a generic text-as-texture classification scheme and apply it to writer identification. In experiments on CVL and ICDAR 2013 datasets, the proposed feature-set demonstrates State-Of-the-Art (SOA) performance. Among the SOA, the proposed method is the only one that is based on dense extraction of a single local feature descriptor. This makes it fast and applicable at the earliest stages in a DIA pipeline without the need for segmentation, binarization, or extraction of multiple features. | ||||
Address | Nancy; France; August 2015 | ||||
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ISSN | ISBN | Medium | |||
Area | Expedition | Conference | ICDAR | ||
Notes | DAG; 600.077 | Approved | no | ||
Call Number | Admin @ si @ NBL2015 | Serial | 2692 | ||
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Author | Angel Valencia; Roger Idrovo; Angel Sappa; Douglas Plaza; Daniel Ochoa | ||||
Title | A 3D Vision Based Approach for Optimal Grasp of Vacuum Grippers | Type | Conference Article | ||
Year | 2017 | Publication | IEEE International Workshop of Electronics, Control, Measurement, Signals and their application to Mechatronics | Abbreviated Journal | |
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Abstract | In general, robot grasping approaches are based on the usage of multi-finger grippers. However, when large size objects need to be manipulated vacuum grippers are preferred, instead of finger based grippers. This paper aims to estimate the best picking place for a two suction cups vacuum gripper,
when planar objects with an unknown size and geometry are considered. The approach is based on the estimation of geometric properties of object’s shape from a partial cloud of points (a single 3D view), in such a way that combine with considerations of a theoretical model to generate an optimal contact point that minimizes the vacuum force needed to guarantee a grasp. Experimental results in real scenarios are presented to show the validity of the proposed approach. |
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Address | San Sebastian; Spain; May 2017 | ||||
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Language | Summary Language | Original Title | |||
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ISSN | ISBN | Medium | |||
Area | Expedition | Conference | ECMSM | ||
Notes | ADAS; 600.086; 600.118 | Approved | no | ||
Call Number | Admin @ si @ VIS2017 | Serial | 2917 | ||
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Author | Angel Sappa; Rosa Herrero; Fadi Dornaika; David Geronimo; Antonio Lopez | ||||
Title | Road Approximation in Euclidean and v-Disparity Space: A Comparative Study | Type | Conference Article | ||
Year | 2007 | Publication | Computer Aided Systems Theory, | Abbreviated Journal | |
Volume | 4739 | Issue | Pages | 1105–1112 | |
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Abstract | This paper presents a comparative study between two road approximation techniques—planar surfaces—from stereo vision data. The first approach is carried out in the v-disparity space and is based on a voting scheme, the Hough transform. The second one consists in computing the best fitting plane for the whole 3D road data points, directly in the Euclidean space, by using least squares fitting. The comparative study is initially performed over a set of different synthetic surfaces
(e.g., plane, quadratic surface, cubic surface) digitized by a virtual stereo head; then real data obtained with a commercial stereo head are used. The comparative study is intended to be used as a criterion for fining the best technique according to the road geometry. Additionally, it highlights common problems driven from a wrong assumption about the scene’s prior knowledge. |
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Address | Las Palmas de Gran Canaria (Spain) | ||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Summary Language | Original Title | |||
Series Editor | Series Title | Abbreviated Series Title | LNCS | ||
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ISSN | ISBN | Medium | |||
Area | Expedition | Conference | EUROCAST | ||
Notes | ADAS | Approved | no | ||
Call Number | ADAS @ adas @ SHD2007b | Serial | 917 | ||
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Author | Angel Sappa; Rosa Herrero; Fadi Dornaika; David Geronimo; Antonio Lopez | ||||
Title | Road Approximation in Euclidean and v-Disparity Space: A Comparative Study | Type | Conference Article | ||
Year | 2007 | Publication | EUROCAST2007, Workshop on Cybercars and Intelligent Vehicles | Abbreviated Journal | |
Volume | Issue | Pages | 368–369 | ||
Keywords | |||||
Abstract | This paper presents a comparative study between two road approximation techniques—planar surfaces—from stereo vision data. The first approach is carried out in the v-disparity space and is based on a voting scheme, the Hough transform. The second one consists in computing the best fitting plane for the whole 3D road data points, directly in the Euclidean space, by using least squares fitting. The comparative study is initially performed over a set of different synthetic surfaces
(e.g., plane, quadratic surface, cubic surface) digitized by a virtual stereo head; then real data obtained with a commercial stereo head are used. The comparative study is intended to be used as a criterion for fining the best technique according to the road geometry. Additionally, it highlights common problems driven from a wrong assumption about the scene’s prior knowledge. |
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Address | Las Palmas de Gran Canaria (Spain) | ||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | Summary Language | Original Title | |||
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | ISBN | Medium | |||
Area | Expedition | Conference | |||
Notes | ADAS | Approved | no | ||
Call Number | ADAS @ adas @ SHD2007a | Serial | 936 | ||
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Author | Angel Sappa; Patricia Suarez; Henry Velesaca; Dario Carpio | ||||
Title | Domain Adaptation in Image Dehazing: Exploring the Usage of Images from Virtual Scenarios | Type | Conference Article | ||
Year | 2022 | Publication | 16th International Conference on Computer Graphics, Visualization, Computer Vision and Image Processing | Abbreviated Journal | |
Volume | Issue | Pages | 85-92 | ||
Keywords | Domain adaptation; Synthetic hazed dataset; Dehazing | ||||
Abstract | This work presents a novel domain adaptation strategy for deep learning-based approaches to solve the image dehazing
problem. Firstly, a large set of synthetic images is generated by using a realistic 3D graphic simulator; these synthetic images contain different densities of haze, which are used for training the model that is later adapted to any real scenario. The adaptation process requires just a few images to fine-tune the model parameters. The proposed strategy allows overcoming the limitation of training a given model with few images. In other words, the proposed strategy implements the adaptation of a haze removal model trained with synthetic images to real scenarios. It should be noticed that it is quite difficult, if not impossible, to have large sets of pairs of real-world images (with and without haze) to train in a supervised way dehazing algorithms. Experimental results are provided showing the validity of the proposed domain adaptation strategy. |
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Address | Lisboa; Portugal; July 2022 | ||||
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Area | Expedition | Conference | CGVCVIP | ||
Notes | MSIAU; no proj | Approved | no | ||
Call Number | Admin @ si @ SSV2022 | Serial | 3804 | ||
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Author | Angel Sappa; P. Carvajal; Cristhian A. Aguilera-Carrasco; Miguel Oliveira; Dennis Romero; Boris X. Vintimilla | ||||
Title | Wavelet based visible and infrared image fusion: a comparative study | Type | Journal Article | ||
Year | 2016 | Publication | Sensors | Abbreviated Journal | SENS |
Volume | 16 | Issue | 6 | Pages | 1-15 |
Keywords | Image fusion; fusion evaluation metrics; visible and infrared imaging; discrete wavelet transform | ||||
Abstract | This paper evaluates different wavelet-based cross-spectral image fusion strategies adopted to merge visible and infrared images. The objective is to find the best setup independently of the evaluation metric used to measure the performance. Quantitative performance results are obtained with state of the art approaches together with adaptations proposed in the current work. The options evaluated in the current work result from the combination of different setups in the wavelet image decomposition stage together with different fusion strategies for the final merging stage that generates the resulting representation. Most of the approaches evaluate results according to the application for which they are intended for. Sometimes a human observer is selected to judge the quality of the obtained results. In the current work, quantitative values are considered in order to find correlations between setups and performance of obtained results; these correlations can be used to define a criteria for selecting the best fusion strategy for a given pair of cross-spectral images. The whole procedure is evaluated with a large set of correctly registered visible and infrared image pairs, including both Near InfraRed (NIR) and Long Wave InfraRed (LWIR). | ||||
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Notes | ADAS; 600.086; 600.076 | Approved | no | ||
Call Number | Admin @ si @SCA2016 | Serial | 2807 | ||
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Author | Angel Sappa; Niki Aifanti; Sotiris Malassiotis; N. Grammalidis | ||||
Title | Survey of 3D Human Body Representations | Type | Book Chapter | ||
Year | 2005 | Publication | Encyclopedia of Information Science and Technology, 1(5):2696–2701 | Abbreviated Journal | |
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Notes | Approved | no | |||
Call Number | ADAS @ adas @ SAM2005a | Serial | 497 | ||
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Author | Angel Sappa; Niki Aifanti; Sotiris Malassiotis; Michael G. Strintzis | ||||
Title | Monocular 3D Human Body Reconstruction Towards Depth Augmentation of Television Sequences | Type | Conference Article | ||
Year | 2003 | Publication | IEEE International Conference on Image Processing, Barcelona, Spain, September 2003 | Abbreviated Journal | |
Volume | Issue | Pages | 325-328 | ||
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Address | Barcelona | ||||
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Notes | ADAS | Approved | no | ||
Call Number | ADAS @ adas @ SAM2003 | Serial | 418 | ||
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Author | Angel Sappa; Niki Aifanti; Sotiris Malassiotis; Michael G. Strintzis | ||||
Title | Unsupervised Motion Classification by means of Efficient Feature Selection and Tracking | Type | Miscellaneous | ||
Year | 2004 | Publication | IEEE Int. Symp. on 3D Data Processing, Visualization and Transmission | Abbreviated Journal | |
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Address | Thessaloniki (Greece) | ||||
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Notes | Approved | no | |||
Call Number | ADAS @ adas @ SAM2004a | Serial | 456 | ||
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Author | Angel Sappa; Niki Aifanti; Sotiris Malassiotis; Michael G. Strintzis | ||||
Title | 3D Human Walking Modelling | Type | Book Whole | ||
Year | 2004 | Publication | Articulated Motion and Deformable Objects, Third International Workshop, (AMDO 2004), Lecture Notes in Computer Science, F.J. Perales, B.A. Draper (Eds.), 3179:111–122 | Abbreviated Journal | |
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Address | Springer-Verlag, Berlin, Heidelberg | ||||
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Area | Expedition | Conference | |||
Notes | Approved | no | |||
Call Number | ADAS @ adas @ SAM2004b | Serial | 494 | ||
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Author | Angel Sappa; Niki Aifanti; Sotiris Malassiotis; Michael G. Strintzis | ||||
Title | 3D Gait Estimation from Monoscopic Video | Type | Miscellaneous | ||
Year | 2004 | Publication | IEEE International Conference on Image Processing | Abbreviated Journal | |
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Address | Singapore | ||||
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Notes | ADAS | Approved | no | ||
Call Number | ADAS @ adas @ SAM2004c | Serial | 495 | ||
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