A Visual Similarity-Based 3D Search Engine

Lmaati, Elmustapha Ait; Oirrak, Ahmed El; Kaddioui, Mohammed Najib

doi:10.2481/dsj.007-069

Cited by 2 publications

(1 citation statement)

References 12 publications

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“…The comparison of 3-dimensional shapes remains an active topic in computer science (Lmaati et al, 2009). The approach employed here is to construct a dissimilarity matrix of rank n where n is the nth largest event as defined by the n neighbouring voxels of which it is comprised.…”

Section: Similaritymentioning

confidence: 99%

A spatio‐temporal structure‐based approach to drought characterisation

Lloyd‐Hughes

2011

Intl Journal of Climatology

179

105

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Drought characterisation is an intrinsically spatio-temporal problem. A limitation of previous approaches to characterisation is that they discard much of the spatio-temporal information by reducing events to a lower-order subspace. To address this, an explicit 3-dimensional (longitude, latitude, time) structure-based method is described in which drought events are defined by a spatially and temporarily coherent set of points displaying standardised precipitation below a given threshold. Geometric methods can then be used to measure similarity between individual drought structures. Groupings of these similarities provide an alternative to traditional methods for extracting recurrent space-time signals from geophysical data. The explicit consideration of structure encourages the construction of summary statistics which relate to the event geometry. Example measures considered are the event volume, centroid, and aspect ratio. The utility of a 3-dimensional approach is demonstrated by application to the analysis of European droughts (15°W to 35°E, and 35°N to 70°N) for the period 1901-2006. Large-scale structure is found to be abundant with 75 events identified lasting for more than 3 months and spanning at least 0.5 × 10 6 km 2 . Near-complete dissimilarity is seen between the individual drought structures, and little or no regularity is found in the time evolution of even the most spatially similar drought events. The spatial distribution of the event centroids and the time evolution of the geographic cross-sectional areas strongly suggest that large area, sustained droughts result from the combination of multiple small area (∼10 6 km 2 ) short duration (∼3 months) events. The small events are not found to occur independently in space. This leads to the hypothesis that local water feedbacks play an important role in the aggregation process.

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Section: Similaritymentioning

confidence: 99%

A spatio‐temporal structure‐based approach to drought characterisation

Lloyd‐Hughes

2011

Intl Journal of Climatology

179

105

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Content-based navigation within virtual museums

Koutsoudis

Makarona

Pavlidis

2012

Journal of Advanced Computer Science &Amp; Technology

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The ongoing evolution of the Internet has enabled web applications that use real time three-dimensional (3D) graphics and virtual environments. Moreover, in recent years, cultural technology has also flourished notably. Virtual museums represent one significant application that combines culture with modern technologies and the internet, requiring an interdisciplinary approach aiming both at dissemination and education. We present our approach to enhance virtual museums by incorporating content-based retrieval that refers to 3D objects. In this context, a virtual visitor is able to navigate within the museum, examine the exhibited artifacts and perform queries-byexample in order to locate the position of related artifacts. The retrieval mechanism responds to the visitor's queries by indicating similar artifacts, which are ranked according to their similarity scores. This way, the visitor is able to navigate within a virtual museum not only by means of a virtual walkthrough but also by means of the context.

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A Visual Similarity-Based 3D Search Engine

Cited by 2 publications

References 12 publications

A spatio‐temporal structure‐based approach to drought characterisation

A spatio‐temporal structure‐based approach to drought characterisation

Content-based navigation within virtual museums

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