Google Earth is a virtual globe program, allowing viewers to visualize data on top of displayed satellite images of the Earth’s surface. Launched in 2005 and released to the public in 2006, Google Earth fast became a household name hailed as a revolution for humanitarian development, much as Geographic Information Systems (GIS) were several decades ago. According to MapAction, “There seem at present tobe two distinct groups of humanitarian practitioners: those who are already, albeit tentatively,exploiting Google Earth and related geospatial methods in their work,and those whowill be, as soon as they see their first demonstration of its potential.” (MapAction, 2008: 9)
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Tagging is an important way for users to succinctly describe the content they upload to the Internet. However, most tag-suggestion systems recommend words that are highly correlated with the existing tag set, and thus add little information to a user’s contribution. This paper describes a means to determine the ambiguity of a set of (user-contributed) tags and suggests new tags that disambiguate the original tags. We introduce a probabilistic framework that allows us to find two tags that appear in different contexts but are both likely to co-occur with the original tag set. If such tags can be found, the current description is considered “ambiguous” and the two tags are recommended to the user for further clarification. In contrast to previous work, we only query the user when information is most needed and good suggestions are available. We verify the efficacy of our approach using geographical, temporal and semantic metadata, and a user study. We built our system using statistics from a large (100M) database of images and their tags.
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Modern Geographical Information Systems (GIS) [1] provide a service-oriented architecture for interacting with geographical data sets and related maps. Web-based GIS systems are architected around the same principles as more general Web service systems based on SOAP [2], WSDL [3], and REST. Mirroring the World Wide Web Consortium and OASIS Web service standards-making bodies, the Open Geospatial Consortium [5] defines open standards for messages, XML data formats, and access protocols that are specific to the GIS community. In addition to OGC-based services, there are many companies (such as ESRI and AutoDesk) that provide proprietary, commercial solutions. Services from these various providers are not normally interoperable.
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