53,673 research outputs found
Queensland University of Technology at TREC 2005
The Information Retrieval and Web Intelligence (IR-WI) research group is a research team at the Faculty of Information Technology, QUT, Brisbane, Australia. The IR-WI group participated in the Terabyte and Robust track at TREC 2005, both for the first time. For the Robust track we applied our existing information retrieval system that was originally designed for use with structured (XML) retrieval to the domain of document retrieval. For the Terabyte track we experimented with an open source IR system, Zettair and performed two types of experiments. First, we compared Zettair’s performance on both a high-powered supercomputer and a distributed system across seven midrange personal computers. Second, we compared Zettair’s performance when a standard TREC title is used, compared with a natural language query, and a query expanded with synonyms. We compare the systems both in terms of efficiency and retrieval performance. Our results indicate that the distributed system is faster than the supercomputer, while slightly decreasing retrieval performance, and that natural language queries also slightly decrease retrieval performance, while our query expansion technique significantly decreased performance
Examining and improving the effectiveness of relevance feedback for retrieval of scanned text documents
Important legacy paper documents are digitized and collected in online accessible archives. This enables the preservation, sharing, and significantly the searching of
these documents. The text contents of these document images can be transcribed automatically using OCR systems and then stored in an information retrieval system. However, OCR systems make errors in character recognition which have previously been shown to impact on document retrieval behaviour. In particular relevance feedback query-expansion methods, which are often effective for improving electronic
text retrieval, are observed to be less reliable for retrieval of scanned document images. Our experimental examination of the effects of character recognition errors
on an ad hoc OCR retrieval task demonstrates that, while baseline information retrieval can remain relatively unaffected by transcription errors, relevance feedback via query expansion becomes highly unstable. This paper examines the reason for this behaviour, and introduces novel modifications to standard relevance feedback methods. These methods are shown experimentally to improve the effectiveness of relevance feedback for errorful OCR transcriptions. The new methods combine similar recognised character strings based on term collection frequency and a string edit-distance measure. The techniques are domain independent and make no use of external resources such as dictionaries or training data
Document expansion for image retrieval
Successful information retrieval requires e�ective matching
between the user's search request and the contents of relevant
documents. Often the request entered by a user may
not use the same topic relevant terms as the authors' of the
documents. One potential approach to address problems
of query-document term mismatch is document expansion
to include additional topically relevant indexing terms in a
document which may encourage its retrieval when relevant
to queries which do not match its original contents well. We
propose and evaluate a new document expansion method
using external resources. While results of previous research
have been inconclusive in determining the impact of document
expansion on retrieval e�ectiveness, our method is
shown to work e�ectively for text-based image retrieval of
short image annotation documents. Our approach uses the
Okapi query expansion algorithm as a method for document
expansion. We further show improved performance can be
achieved by using a \document reduction" approach to include
only the signi�cant terms in a document in the expansion
process. Our experiments on the WikipediaMM task at
ImageCLEF 2008 show an increase of 16.5% in mean average
precision (MAP) compared to a variation of Okapi BM25 retrieval
model. To compare document expansion with query
expansion, we also test query expansion from an external resource
which leads an improvement by 9.84% in MAP over
our baseline. Our conclusion is that the document expansion
with document reduction and in combination with query expansion
produces the overall best retrieval results for shortlength
document retrieval. For this image retrieval task, we
also concluded that query expansion from external resource
does not outperform the document expansion method
Utilising semantic technologies for intelligent indexing and retrieval of digital images
The proliferation of digital media has led to a huge interest in classifying and indexing media objects for generic search and usage. In particular, we are witnessing colossal growth in digital image repositories that are difficult to navigate using free-text search mechanisms, which often return inaccurate matches as they in principle rely on statistical analysis of query keyword recurrence in the image annotation or surrounding text. In this paper we present a semantically-enabled image annotation and retrieval engine that is designed to satisfy the requirements of the commercial image collections market in terms of both accuracy and efficiency of the retrieval process. Our search engine relies on methodically structured ontologies for image annotation, thus allowing for more intelligent reasoning about the image content and subsequently obtaining a more accurate set of results and a richer set of alternatives matchmaking the original query. We also show how our well-analysed and designed domain ontology contributes to the implicit expansion of user queries as well as the exploitation of lexical databases for explicit semantic-based query expansion
User - Thesaurus Interaction in a Web-Based Database: An Evaluation of Users' Term Selection Behaviour
A major challenge faced by users during the information search and retrieval process is the selection of search terms for query formulation and expansion. Thesauri are recognised as one source of search terms which can assist users in query construction and expansion. As the number of electronic thesauri attached to information retrieval systems has grown, a range of interface facilities and features have been developed to aid users in formulating their queries. The pilot study reported here aimed to explore and evaluate how a thesaurus-enhanced search interface assisted end-users in selecting search terms. Specifically, it focused on the evaluation of users' attitudes toward both the thesaurus and its interface as tools for facilitating search term selection for query expansion. Thesaurusbased searching and browsing behaviours adopted by users while interacting with a thesaurus-enhanced search interface were also examined
- …