Detection-by-Localization: Maintenance-Free Change Object Detector

Recent researches demonstrate that self-localization performance is a very useful measure of likelihood-of-change (LoC) for change detection. In this paper, this "detection-by-localization" scheme is studied in a novel generalized task of object-level change detection. In our framework, a given query image is segmented into object-level subimages (termed "scene parts"), which are then converted to subimage-level pixel-wise LoC maps via the detection-by-localization scheme. Our approach models a self-localization system as a ranking function, outputting a ranked list of reference images, without requiring relevance score. Thanks to this new setting, we can generalize our approach to a broad class of self-localization systems. Our ranking based self-localization model allows to fuse self-localization results from different modalities via an unsupervised rank fusion derived from a field of multi-modal information retrieval (MMR).Comment: 7 pages, 3 figures, Technical repor

Approaches to implement and evaluate aggregated search

La recherche d'information agrégée peut être vue comme un troisième paradigme de recherche d'information après la recherche d'information ordonnée (ranked retrieval) et la recherche d'information booléenne (boolean retrieval). Les deux paradigmes les plus explorés jusqu'à aujourd'hui retournent un ensemble ou une liste ordonnée de résultats. C'est à l'usager de parcourir ces ensembles/listes et d'en extraire l'information nécessaire qui peut se retrouver dans plusieurs documents. De manière alternative, la recherche d'information agrégée ne s'intéresse pas seulement à l'identification des granules (nuggets) d'information pertinents, mais aussi à l'assemblage d'une réponse agrégée contenant plusieurs éléments. Dans nos travaux, nous analysons les travaux liés à la recherche d'information agrégée selon un schéma général qui comprend 3 parties: dispatching de la requête, recherche de granules d'information et agrégation du résultat. Les approches existantes sont groupées autours de plusieurs perspectives générales telle que la recherche relationnelle, la recherche fédérée, la génération automatique de texte, etc. Ensuite, nous nous sommes focalisés sur deux pistes de recherche selon nous les plus prometteuses: (i) la recherche agrégée relationnelle et (ii) la recherche agrégée inter-verticale. * La recherche agrégée relationnelle s'intéresse aux relations entre les granules d'information pertinents qui servent à assembler la réponse agrégée. En particulier, nous nous sommes intéressés à trois types de requêtes notamment: requête attribut (ex. président de la France, PIB de l'Italie, maire de Glasgow, ...), requête instance (ex. France, Italie, Glasgow, Nokia e72, ...) et requête classe (pays, ville française, portable Nokia, ...). Pour ces requêtes qu'on appelle requêtes relationnelles nous avons proposés trois approches pour permettre la recherche de relations et l'assemblage des résultats. Nous avons d'abord mis l'accent sur la recherche d'attributs qui peut aider à répondre aux trois types de requêtes. Nous proposons une approche à large échelle capable de répondre à des nombreuses requêtes indépendamment de la classe d'appartenance. Cette approche permet l'extraction des attributs à partir des tables HTML en tenant compte de la qualité des tables et de la pertinence des attributs. Les différentes évaluations de performances effectuées prouvent son efficacité qui dépasse les méthodes de l'état de l'art. Deuxièmement, nous avons traité l'agrégation des résultats composés d'instances et d'attributs. Ce problème est intéressant pour répondre à des requêtes de type classe avec une table contenant des instances (lignes) et des attributs (colonnes). Pour garantir la qualité du résultat, nous proposons des pondérations sur les instances et les attributs promouvant ainsi les plus représentatifs. Le troisième problème traité concerne les instances de la même classe (ex. France, Italie, Allemagne, ...). Nous proposons une approche capable d'identifier massivement ces instances en exploitant les listes HTML. Toutes les approches proposées fonctionnent à l'échelle Web et sont importantes et complémentaires pour la recherche agrégée relationnelle. Enfin, nous proposons 4 prototypes d'application de recherche agrégée relationnelle. Ces derniers peuvent répondre des types de requêtes différents avec des résultats relationnels. Plus précisément, ils recherchent et assemblent des attributs, des instances, mais aussi des passages et des images dans des résultats agrégés. Un exemple est la requête ``Nokia e72" dont la réponse sera composée d'attributs (ex. prix, poids, autonomie batterie, ...), de passages (ex. description, reviews, ...) et d'images. Les résultats sont encourageants et illustrent l'utilité de la recherche agrégée relationnelle. * La recherche agrégée inter-verticale s'appuie sur plusieurs moteurs de recherche dits verticaux tel que la recherche d'image, recherche vidéo, recherche Web traditionnelle, etc. Son but principal est d'assembler des résultats provenant de toutes ces sources dans une même interface pour répondre aux besoins des utilisateurs. Les moteurs de recherche majeurs et la communauté scientifique nous offrent déjà une série d'approches. Notre contribution consiste en une étude sur l'évaluation et les avantages de ce paradigme. Plus précisément, nous comparons 4 types d'études qui simulent des situations de recherche sur un total de 100 requêtes et 9 sources différentes. Avec cette étude, nous avons identifiés clairement des avantages de la recherche agrégée inter-verticale et nous avons pu déduire de nombreux enjeux sur son évaluation. En particulier, l'évaluation traditionnelle utilisée en RI, certes la moins rapide, reste la plus réaliste. Pour conclure, nous avons proposé des différents approches et études sur deux pistes prometteuses de recherche dans le cadre de la recherche d'information agrégée. D'une côté, nous avons traité trois problèmes importants de la recherche agrégée relationnelle qui ont porté à la construction de 4 prototypes d'application avec des résultats encourageants. De l'autre côté, nous avons mis en place 4 études sur l'intérêt et l'évaluation de la recherche agrégée inter-verticale qui ont permis d'identifier les enjeux d'évaluation et les avantages du paradigme. Comme suite à long terme de ce travail, nous pouvons envisager une recherche d'information qui intègre plus de granules relationnels et plus de multimédia.Aggregated search or aggregated retrieval can be seen as a third paradigm for information retrieval following the Boolean retrieval paradigm and the ranked retrieval paradigm. In the first two, we are returned respectively sets and ranked lists of search results. It is up to the time-poor user to scroll this set/list, scan within different documents and assemble his/her information need. Alternatively, aggregated search not only aims the identification of relevant information nuggets, but also the assembly of these nuggets into a coherent answer. In this work, we present at first an analysis of related work to aggregated search which is analyzed with a general framework composed of three steps: query dispatching, nugget retrieval and result aggregation. Existing work is listed aside different related domains such as relational search, federated search, question answering, natural language generation, etc. Within the possible research directions, we have then focused on two directions we believe promise the most namely: relational aggregated search and cross-vertical aggregated search. * Relational aggregated search targets relevant information, but also relations between relevant information nuggets which are to be used to assemble reasonably the final answer. In particular, there are three types of queries which would easily benefit from this paradigm: attribute queries (e.g. president of France, GDP of Italy, major of Glasgow, ...), instance queries (e.g. France, Italy, Glasgow, Nokia e72, ...) and class queries (countries, French cities, Nokia mobile phones, ...). We call these queries as relational queries and we tackle with three important problems concerning the information retrieval and aggregation for these types of queries. First, we propose an attribute retrieval approach after arguing that attribute retrieval is one of the crucial problems to be solved. Our approach relies on the HTML tables in the Web. It is capable to identify useful and relevant tables which are used to extract relevant attributes for whatever queries. The different experimental results show that our approach is effective, it can answer many queries with high coverage and it outperforms state of the art techniques. Second, we deal with result aggregation where we are given relevant instances and attributes for a given query. The problem is particularly interesting for class queries where the final answer will be a table with many instances and attributes. To guarantee the quality of the aggregated result, we propose the use of different weights on instances and attributes to promote the most representative and important ones. The third problem we deal with concerns instances of the same class (e.g. France, Germany, Italy ... are all instances of the same class). Here, we propose an approach that can massively extract instances of the same class from HTML lists in the Web. All proposed approaches are applicable at Web-scale and they can play an important role for relational aggregated search. Finally, we propose 4 different prototype applications for relational aggregated search. They can answer different types of queries with relevant and relational information. Precisely, we not only retrieve attributes and their values, but also passages and images which are assembled into a final focused answer. An example is the query ``Nokia e72" which will be answered with attributes (e.g. price, weight, battery life ...), passages (e.g. description, reviews ...) and images. Results are encouraging and they illustrate the utility of relational aggregated search. * The second research direction that we pursued concerns cross-vertical aggregated search, which consists of assembling results from different vertical search engines (e.g. image search, video search, traditional Web search, ...) into one single interface. Here, different approaches exist in both research and industry. Our contribution concerns mostly evaluation and the interest (advantages) of this paradigm. We propose 4 different studies which simulate different search situations. Each study is tested with 100 different queries and 9 vertical sources. Here, we could clearly identify new advantages of this paradigm and we could identify different issues with evaluation setups. In particular, we observe that traditional information retrieval evaluation is not the fastest but it remains the most realistic. To conclude, we propose different studies with respect to two promising research directions. On one hand, we deal with three important problems of relational aggregated search following with real prototype applications with encouraging results. On the other hand, we have investigated on the interest and evaluation of cross-vertical aggregated search. Here, we could clearly identify some of the advantages and evaluation issues. In a long term perspective, we foresee a possible combination of these two kinds of approaches to provide relational and cross-vertical information retrieval incorporating more focus, structure and multimedia in search results

On Choosing Games And What Counts as a “Good” Game

Before researchers can perform studies using commercial games, they must choose which game or games to study. The manner in which that choice is made and justified is the focus of this paper

Peer to Peer Information Retrieval: An Overview

Peer-to-peer technology is widely used for file sharing. In the past decade a number of prototype peer-to-peer information retrieval systems have been developed. Unfortunately, none of these have seen widespread real- world adoption and thus, in contrast with file sharing, information retrieval is still dominated by centralised solutions. In this paper we provide an overview of the key challenges for peer-to-peer information retrieval and the work done so far. We want to stimulate and inspire further research to overcome these challenges. This will open the door to the development and large-scale deployment of real-world peer-to-peer information retrieval systems that rival existing centralised client-server solutions in terms of scalability, performance, user satisfaction and freedom

The THUMOS Challenge on Action Recognition for Videos "in the Wild"

Automatically recognizing and localizing wide ranges of human actions has crucial importance for video understanding. Towards this goal, the THUMOS challenge was introduced in 2013 to serve as a benchmark for action recognition. Until then, video action recognition, including THUMOS challenge, had focused primarily on the classification of pre-segmented (i.e., trimmed) videos, which is an artificial task. In THUMOS 2014, we elevated action recognition to a more practical level by introducing temporally untrimmed videos. These also include `background videos' which share similar scenes and backgrounds as action videos, but are devoid of the specific actions. The three editions of the challenge organized in 2013--2015 have made THUMOS a common benchmark for action classification and detection and the annual challenge is widely attended by teams from around the world. In this paper we describe the THUMOS benchmark in detail and give an overview of data collection and annotation procedures. We present the evaluation protocols used to quantify results in the two THUMOS tasks of action classification and temporal detection. We also present results of submissions to the THUMOS 2015 challenge and review the participating approaches. Additionally, we include a comprehensive empirical study evaluating the differences in action recognition between trimmed and untrimmed videos, and how well methods trained on trimmed videos generalize to untrimmed videos. We conclude by proposing several directions and improvements for future THUMOS challenges.Comment: Preprint submitted to Computer Vision and Image Understandin

Aggregated search: a new information retrieval paradigm

International audienceTraditional search engines return ranked lists of search results. It is up to the user to scroll this list, scan within different documents and assemble information that fulfill his/her information need. Aggregated search represents a new class of approaches where the information is not only retrieved but also assembled. This is the current evolution in Web search, where diverse content (images, videos, ...) and relational content (similar entities, features) are included in search results. In this survey, we propose a simple analysis framework for aggregated search and an overview of existing work. We start with related work in related domains such as federated search, natural language generation and question answering. Then we focus on more recent trends namely cross vertical aggregated search and relational aggregated search which are already present in current Web search

Inexpensive fusion methods for enhancing feature detection

Recent successful approaches to high-level feature detection in image and video data have treated the problem as a pattern classification task. These typically leverage the techniques learned from statistical machine learning, coupled with ensemble architectures that create multiple feature detection models. Once created, co-occurrence between learned features can be captured to further boost performance. At multiple stages throughout these frameworks, various pieces of evidence can be fused together in order to boost performance. These approaches whilst very successful are computationally expensive, and depending on the task, require the use of significant computational resources. In this paper we propose two fusion methods that aim to combine the output of an initial basic statistical machine learning approach with a lower-quality information source, in order to gain diversity in the classified results whilst requiring only modest computing resources. Our approaches, validated experimentally on TRECVid data, are designed to be complementary to existing frameworks and can be regarded as possible replacements for the more computationally expensive combination strategies used elsewhere

Uncertainty-Aware Organ Classification for Surgical Data Science Applications in Laparoscopy

Objective: Surgical data science is evolving into a research field that aims to observe everything occurring within and around the treatment process to provide situation-aware data-driven assistance. In the context of endoscopic video analysis, the accurate classification of organs in the field of view of the camera proffers a technical challenge. Herein, we propose a new approach to anatomical structure classification and image tagging that features an intrinsic measure of confidence to estimate its own performance with high reliability and which can be applied to both RGB and multispectral imaging (MI) data. Methods: Organ recognition is performed using a superpixel classification strategy based on textural and reflectance information. Classification confidence is estimated by analyzing the dispersion of class probabilities. Assessment of the proposed technology is performed through a comprehensive in vivo study with seven pigs. Results: When applied to image tagging, mean accuracy in our experiments increased from 65% (RGB) and 80% (MI) to 90% (RGB) and 96% (MI) with the confidence measure. Conclusion: Results showed that the confidence measure had a significant influence on the classification accuracy, and MI data are better suited for anatomical structure labeling than RGB data. Significance: This work significantly enhances the state of art in automatic labeling of endoscopic videos by introducing the use of the confidence metric, and by being the first study to use MI data for in vivo laparoscopic tissue classification. The data of our experiments will be released as the first in vivo MI dataset upon publication of this paper.Comment: 7 pages, 6 images, 2 table