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Author Marco Pedersoli; Andrea Vedaldi; Jordi Gonzalez; Xavier Roca edit   pdf
doi  openurl
  Title A coarse-to-fine approach for fast deformable object detection Type Journal Article
  Year 2015 Publication Pattern Recognition Abbreviated Journal PR  
  Volume 48 Issue (up) 5 Pages 1844-1853  
  Keywords  
  Abstract We present a method that can dramatically accelerate object detection with part based models. The method is based on the observation that the cost of detection is likely to be dominated by the cost of matching each part to the image, and not by the cost of computing the optimal configuration of the parts as commonly assumed. Therefore accelerating detection requires minimizing the number of
part-to-image comparisons. To this end we propose a multiple-resolutions hierarchical part based model and a corresponding coarse-to-fine inference procedure that recursively eliminates from the search space unpromising part
placements. The method yields a ten-fold speedup over the standard dynamic programming approach and is complementary to the cascade-of-parts approach of [9]. Compared to the latter, our method does not have parameters to be determined empirically, which simplifies its use during the training of the model. Most importantly, the two techniques can be combined to obtain a very significant speedup, of two orders of magnitude in some cases. We evaluate our method extensively on the PASCAL VOC and INRIA datasets, demonstrating a very high increase in the detection speed with little degradation of the accuracy.
 
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  Notes ISE; 600.078; 602.005; 605.001; 302.012 Approved no  
  Call Number Admin @ si @ PVG2015 Serial 2628  
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Author Francisco Javier Orozco; Xavier Roca; Jordi Gonzalez edit  url
doi  openurl
  Title Real-Time Gaze Tracking with Appearance-Based Models Type Journal Article
  Year 2008 Publication Machine Vision Applications Abbreviated Journal MVAP  
  Volume 20 Issue (up) 6 Pages 353-364  
  Keywords Keywords Eyelid and iris tracking, Appearance models, Blinking, Iris saccade, Real-time gaze tracking  
  Abstract Psychological evidence has emphasized the importance of eye gaze analysis in human computer interaction and emotion interpretation. To this end, current image analysis algorithms take into consideration eye-lid and iris motion detection using colour information and edge detectors. However, eye movement is fast and and hence difficult to use to obtain a precise and robust tracking. Instead, our
method proposed to describe eyelid and iris movements as continuous variables using appearance-based tracking. This approach combines the strengths of adaptive appearance models, optimization methods and backtracking techniques.Thus,
in the proposed method textures are learned on-line from near frontal images and illumination changes, occlusions and fast movements are managed. The method achieves real-time performance by combining two appearance-based trackers to a
backtracking algorithm for eyelid estimation and another for iris estimation. These contributions represent a significant advance towards a reliable gaze motion description for HCI and expression analysis, where the strength of complementary
methodologies are combined to avoid using high quality images, colour information, texture training, camera settings and other time-consuming processes.
 
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  Notes ISE Approved no  
  Call Number ISE @ ise @ ORG2008 Serial 972  
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Author Carles Fernandez; Pau Baiget; Xavier Roca; Jordi Gonzalez edit   pdf
doi  openurl
  Title Augmenting Video Surveillance Footage with Virtual Agents for Incremental Event Evaluation Type Journal Article
  Year 2011 Publication Pattern Recognition Letters Abbreviated Journal PRL  
  Volume 32 Issue (up) 6 Pages 878–889  
  Keywords  
  Abstract The fields of segmentation, tracking and behavior analysis demand for challenging video resources to test, in a scalable manner, complex scenarios like crowded environments or scenes with high semantics. Nevertheless, existing public databases cannot scale the presence of appearing agents, which would be useful to study long-term occlusions and crowds. Moreover, creating these resources is expensive and often too particularized to specific needs. We propose an augmented reality framework to increase the complexity of image sequences in terms of occlusions and crowds, in a scalable and controllable manner. Existing datasets can be increased with augmented sequences containing virtual agents. Such sequences are automatically annotated, thus facilitating evaluation in terms of segmentation, tracking, and behavior recognition. In order to easily specify the desired contents, we propose a natural language interface to convert input sentences into virtual agent behaviors. Experimental tests and validation in indoor, street, and soccer environments are provided to show the feasibility of the proposed approach in terms of robustness, scalability, and semantics.  
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  Publisher Elsevier Place of Publication Editor  
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  Notes ISE Approved no  
  Call Number Admin @ si @ FBR2011b Serial 1723  
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Author Marcel P. Lucassen; Theo Gevers; Arjan Gijsenij edit  url
openurl 
  Title Texture Affects Color Emotion Type Journal Article
  Year 2011 Publication Color Research & Applications Abbreviated Journal CRA  
  Volume 36 Issue (up) 6 Pages 426–436  
  Keywords color;texture;color emotion;observer variability;ranking  
  Abstract Several studies have recorded color emotions in subjects viewing uniform color (UC) samples. We conduct an experiment to measure and model how these color emotions change when texture is added to the color samples. Using a computer monitor, our subjects arrange samples along four scales: warm–cool, masculine–feminine, hard–soft, and heavy–light. Three sample types of increasing visual complexity are used: UC, grayscale textures, and color textures (CTs). To assess the intraobserver variability, the experiment is repeated after 1 week. Our results show that texture fully determines the responses on the Hard-Soft scale, and plays a role of decreasing weight for the masculine–feminine, heavy–light, and warm–cool scales. Using some 25,000 observer responses, we derive color emotion functions that predict the group-averaged scale responses from the samples' color and texture parameters. For UC samples, the accuracy of our functions is significantly higher (average R2 = 0.88) than that of previously reported functions applied to our data. The functions derived for CT samples have an accuracy of R2 = 0.80. We conclude that when textured samples are used in color emotion studies, the psychological responses may be strongly affected by texture. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2010  
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  Notes ALTRES;ISE Approved no  
  Call Number Admin @ si @ LGG2011 Serial 1844  
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Author Carles Fernandez; Pau Baiget; Xavier Roca; Jordi Gonzalez edit  openurl
  Title Interpretation of Complex Situations in a Semantic-based Surveillance Framework Type Journal
  Year 2008 Publication Signal Processing: Image Communication, Special Issue on Semantic Analysis for Interactive Multimedia Services Abbreviated Journal  
  Volume 23 Issue (up) 7 Pages 554-569  
  Keywords Cognitive vision system; Situation analysis; Applied ontologies  
  Abstract The integration of cognitive capabilities in computer vision systems requires both to enable high semantic expressiveness and to deal with high computational costs as large amounts of data are involved in the analysis. This contribution describes a cognitive vision system conceived to automatically provide high-level interpretations of complex real-time situations in outdoor and indoor scenarios, and to eventually maintain communication with casual end users in multiple languages. The main contributions are: (i) the design of an integrative multilevel architecture for cognitive surveillance purposes; (ii) the proposal of a coherent taxonomy of knowledge to guide the process of interpretation, which leads to the conception of a situation-based ontology; (iii) the use of situational analysis for content detection and a progressive interpretation of semantically rich scenes, by managing incomplete or uncertain knowledge, and (iv) the use of such an ontological background to enable multilingual capabilities and advanced end-user interfaces. Experimental results are provided to show the feasibility of the proposed approach.  
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  Area Expedition Conference  
  Notes ISE Approved no  
  Call Number ISE @ ise @ FBR2008 Serial 954  
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