793 research outputs found
A Survey of Volunteered Open Geo-Knowledge Bases in the Semantic Web
Over the past decade, rapid advances in web technologies, coupled with
innovative models of spatial data collection and consumption, have generated a
robust growth in geo-referenced information, resulting in spatial information
overload. Increasing 'geographic intelligence' in traditional text-based
information retrieval has become a prominent approach to respond to this issue
and to fulfill users' spatial information needs. Numerous efforts in the
Semantic Geospatial Web, Volunteered Geographic Information (VGI), and the
Linking Open Data initiative have converged in a constellation of open
knowledge bases, freely available online. In this article, we survey these open
knowledge bases, focusing on their geospatial dimension. Particular attention
is devoted to the crucial issue of the quality of geo-knowledge bases, as well
as of crowdsourced data. A new knowledge base, the OpenStreetMap Semantic
Network, is outlined as our contribution to this area. Research directions in
information integration and Geographic Information Retrieval (GIR) are then
reviewed, with a critical discussion of their current limitations and future
prospects
Historical collaborative geocoding
The latest developments in digital have provided large data sets that can
increasingly easily be accessed and used. These data sets often contain
indirect localisation information, such as historical addresses. Historical
geocoding is the process of transforming the indirect localisation information
to direct localisation that can be placed on a map, which enables spatial
analysis and cross-referencing. Many efficient geocoders exist for current
addresses, but they do not deal with the temporal aspect and are based on a
strict hierarchy (..., city, street, house number) that is hard or impossible
to use with historical data. Indeed historical data are full of uncertainties
(temporal aspect, semantic aspect, spatial precision, confidence in historical
source, ...) that can not be resolved, as there is no way to go back in time to
check. We propose an open source, open data, extensible solution for geocoding
that is based on the building of gazetteers composed of geohistorical objects
extracted from historical topographical maps. Once the gazetteers are
available, geocoding an historical address is a matter of finding the
geohistorical object in the gazetteers that is the best match to the historical
address. The matching criteriae are customisable and include several dimensions
(fuzzy semantic, fuzzy temporal, scale, spatial precision ...). As the goal is
to facilitate historical work, we also propose web-based user interfaces that
help geocode (one address or batch mode) and display over current or historical
topographical maps, so that they can be checked and collaboratively edited. The
system is tested on Paris city for the 19-20th centuries, shows high returns
rate and is fast enough to be used interactively.Comment: WORKING PAPE
Spatial information retrieval and geographical ontologies: an overview of the SPIRIT project
A large proportion of the resources available on the world-wide
web refer to information that may be regarded as geographically
located. Thus most activities and enterprises take place in one or
more places on the Earth's surface and there is a wealth of survey
data, images, maps and reports that relate to specific places or
regions. Despite the prevalence of geographical context, existing
web search facilities are poorly adapted to help people find
information that relates to a particular location. When the name of
a place is typed into a typical search engine, web pages that
include that name in their text will be retrieved, but it is likely
that many resources that are also associated with the place may
not be retrieved. Thus resources relating to places that are inside
the specified place may not be found, nor may be places that are
nearby or that are equivalent but referred to by another name.
Specification of geographical context frequently requires the use
of spatial relationships concerning distance or containment for
example, yet such terminology cannot be understood by existing
search engines. Here we provide a brief survey of existing
facilities for geographical information retrieval on the web, before
describing a set of tools and techniques that are being developed
in the project SPIRIT : Spatially-Aware Information Retrieval on
the Internet (funded by European Commission Framework V
Project IST-2001-35047)
Geographical information retrieval with ontologies of place
Geographical context is required of many information retrieval tasks in which the target of the search may be documents, images or records which are referenced to geographical space only by means of place names. Often there may be an imprecise match between the query name and the names associated with candidate sources of information. There is a need therefore for geographical information retrieval facilities that can rank the relevance of candidate information with respect to geographical closeness of place as well as semantic closeness with respect to the information of interest. Here we present an ontology of place that combines limited coordinate data with semantic and qualitative spatial relationships between places. This parsimonious model of geographical place supports maintenance of knowledge of place names that relate to extensive regions of the Earth at multiple levels of granularity. The ontology has been implemented with a semantic modelling system linking non-spatial conceptual hierarchies with the place ontology. An hierarchical spatial distance measure is combined with Euclidean distance between place centroids to create a hybrid spatial distance measure. This is integrated with thematic distance, based on classification semantics, to create an integrated semantic closeness measure that can be used for a relevance ranking of retrieved objects
Geospatial Semantics
Geospatial semantics is a broad field that involves a variety of research
areas. The term semantics refers to the meaning of things, and is in contrast
with the term syntactics. Accordingly, studies on geospatial semantics usually
focus on understanding the meaning of geographic entities as well as their
counterparts in the cognitive and digital world, such as cognitive geographic
concepts and digital gazetteers. Geospatial semantics can also facilitate the
design of geographic information systems (GIS) by enhancing the
interoperability of distributed systems and developing more intelligent
interfaces for user interactions. During the past years, a lot of research has
been conducted, approaching geospatial semantics from different perspectives,
using a variety of methods, and targeting different problems. Meanwhile, the
arrival of big geo data, especially the large amount of unstructured text data
on the Web, and the fast development of natural language processing methods
enable new research directions in geospatial semantics. This chapter,
therefore, provides a systematic review on the existing geospatial semantic
research. Six major research areas are identified and discussed, including
semantic interoperability, digital gazetteers, geographic information
retrieval, geospatial Semantic Web, place semantics, and cognitive geographic
concepts.Comment: Yingjie Hu (2017). Geospatial Semantics. In Bo Huang, Thomas J. Cova,
and Ming-Hsiang Tsou et al. (Eds): Comprehensive Geographic Information
Systems, Elsevier. Oxford, U
Surveying GeoNames Gazetteer Data for the Nordic Countries
This paper takes a look at freely available gazetteer data for the Nordic countries. We examine locations in this region to understand their characteristics and the quality of the available data. Several indicators are developed and discussed to estimate the expected data quality. The distribution and coverage of the data is mapped and the accuracy and quality indicators are visualized. The used method focuses on populated places as locations of interest but can be extended to arbitrary types of locations. The results give insights into the distribution of issues based on multiple indicators and give an estimate of per-country data quality
A Coherent Unsupervised Model for Toponym Resolution
Toponym Resolution, the task of assigning a location mention in a document to
a geographic referent (i.e., latitude/longitude), plays a pivotal role in
analyzing location-aware content. However, the ambiguities of natural language
and a huge number of possible interpretations for toponyms constitute
insurmountable hurdles for this task. In this paper, we study the problem of
toponym resolution with no additional information other than a gazetteer and no
training data. We demonstrate that a dearth of large enough annotated data
makes supervised methods less capable of generalizing. Our proposed method
estimates the geographic scope of documents and leverages the connections
between nearby place names as evidence to resolve toponyms. We explore the
interactions between multiple interpretations of mentions and the relationships
between different toponyms in a document to build a model that finds the most
coherent resolution. Our model is evaluated on three news corpora, two from the
literature and one collected and annotated by us; then, we compare our methods
to the state-of-the-art unsupervised and supervised techniques. We also examine
three commercial products including Reuters OpenCalais, Yahoo! YQL Placemaker,
and Google Cloud Natural Language API. The evaluation shows that our method
outperforms the unsupervised technique as well as Reuters OpenCalais and Google
Cloud Natural Language API on all three corpora; also, our method shows a
performance close to that of the state-of-the-art supervised method and
outperforms it when the test data has 40% or more toponyms that are not seen in
the training data.Comment: 9 pages (+1 page reference), WWW '18 Proceedings of the 2018 World
Wide Web Conferenc
A Framework for Reference Management in the Semantic Web
Much of the semantic web relies upon open and unhindered interoperability between diverse systems. The successful convergence of multiple ontologies and referencing schemes is key. This is hampered by a lack of any means for managing and communicating co-references. We have therefore developed an ontology and framework for the exploration and resolution of potential co-references, in the semantic web at large, that allow the user to a) discover and record uniquely identifying attributes b) interface candidates with and create pipelines of other systems for reference management c) record identified duplicates in a usable and retrievable manner, and d) provide a consistent reference service for accessing them. This paper describes this ontology and a framework of web services designed to support and utilise it
Bipartite Flat-Graph Network for Nested Named Entity Recognition
In this paper, we propose a novel bipartite flat-graph network (BiFlaG) for
nested named entity recognition (NER), which contains two subgraph modules: a
flat NER module for outermost entities and a graph module for all the entities
located in inner layers. Bidirectional LSTM (BiLSTM) and graph convolutional
network (GCN) are adopted to jointly learn flat entities and their inner
dependencies. Different from previous models, which only consider the
unidirectional delivery of information from innermost layers to outer ones (or
outside-to-inside), our model effectively captures the bidirectional
interaction between them. We first use the entities recognized by the flat NER
module to construct an entity graph, which is fed to the next graph module. The
richer representation learned from graph module carries the dependencies of
inner entities and can be exploited to improve outermost entity predictions.
Experimental results on three standard nested NER datasets demonstrate that our
BiFlaG outperforms previous state-of-the-art models.Comment: Accepted by ACL202
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