7,826 research outputs found
Content-based Video Retrieval by Integrating Spatio-Temporal and Stochastic Recognition of Events
As amounts of publicly available video data grow the need to query this data efficiently becomes significant. Consequently content-based retrieval of video data turns out to be a challenging and important problem. We address the specific aspect of inferring semantics automatically from raw video data. In particular, we introduce a new video data model that supports the integrated use of two different approaches for mapping low-level features to high-level concepts. Firstly, the model is extended with a rule-based approach that supports spatio-temporal formalization of high-level concepts, and then with a stochastic approach. Furthermore, results on real tennis video data are presented, demonstrating the validity of both approaches, as well us advantages of their integrated us
Foundations of Relational Particle Dynamics
Relational particle dynamics include the dynamics of pure shape and cases in
which absolute scale or absolute rotation are additionally meaningful. These
are interesting as regards the absolute versus relative motion debate as well
as discussion of conceptual issues connected with the problem of time in
quantum gravity. In spatial dimension 1 and 2 the relative configuration spaces
of shapes are n-spheres and complex projective spaces, from which knowledge I
construct natural mechanics on these spaces. I also show that these coincide
with Barbour's indirectly-constructed relational dynamics by performing a full
reduction on the latter. Then the identification of the configuration spaces as
n-spheres and complex projective spaces, for which spaces much mathematics is
available, significantly advances the understanding of Barbour's relational
theory in spatial dimensions 1 and 2. I also provide the parallel study of a
new theory for which positon and scale are purely relative but orientation is
absolute. The configuration space for this is an n-sphere regardless of the
spatial dimension, which renders this theory a more tractable arena for
investigation of implications of scale invariance than Barbour's theory itself.Comment: Minor typos corrected; references update
A spatiotemporal object-oriented data model for landslides (LOOM)
LOOM (landslide object-oriented model) is here presented as a data structure for landslide inventories based on the object-oriented paradigm. It aims at the effective storage, in a single dataset, of the complex spatial and temporal relations between landslides recorded and mapped in an area and at their manipulation. Spatial relations are handled through a hierarchical classification based on topological rules and two levels of aggregation are defined: (i) landslide complexes, grouping spatially connected landslides of the same type, and (ii) landslide systems, merging landslides of any type sharing a spatial connection. For the aggregation procedure, a minimal functional interaction between landslide objects has been defined as a spatial overlap between objects. Temporal characterization of landslides is achieved by assigning to each object an exact date or a time range for its occurrence, integrating both the time frame and the event-based approaches. The sum of spatial integrity and temporal characterization ensures the storage of vertical relations between landslides, so that the superimposition of events can be easily retrieved querying the temporal dataset. The here proposed methodology for landslides inventorying has been tested on selected case studies in the Cilento UNESCO Global Geopark (Italy). We demonstrate that the proposed LOOM model avoids data fragmentation or redundancy and topological inconsistency between the digital data and the real-world features. This application revealed to be powerful for the reconstruction of the gravity-induced deformation history of hillslopes, thus for the prediction of their evolution
Structured Knowledge Representation for Image Retrieval
We propose a structured approach to the problem of retrieval of images by
content and present a description logic that has been devised for the semantic
indexing and retrieval of images containing complex objects. As other
approaches do, we start from low-level features extracted with image analysis
to detect and characterize regions in an image. However, in contrast with
feature-based approaches, we provide a syntax to describe segmented regions as
basic objects and complex objects as compositions of basic ones. Then we
introduce a companion extensional semantics for defining reasoning services,
such as retrieval, classification, and subsumption. These services can be used
for both exact and approximate matching, using similarity measures. Using our
logical approach as a formal specification, we implemented a complete
client-server image retrieval system, which allows a user to pose both queries
by sketch and queries by example. A set of experiments has been carried out on
a testbed of images to assess the retrieval capabilities of the system in
comparison with expert users ranking. Results are presented adopting a
well-established measure of quality borrowed from textual information
retrieval
Integration of the DOLCE top-level ontology into the OntoSpec methodology
This report describes a new version of the OntoSpec methodology for ontology
building. Defined by the LaRIA Knowledge Engineering Team (University of
Picardie Jules Verne, Amiens, France), OntoSpec aims at helping builders to
model ontological knowledge (upstream of formal representation). The
methodology relies on a set of rigorously-defined modelling primitives and
principles. Its application leads to the elaboration of a semi-informal
ontology, which is independent of knowledge representation languages. We
recently enriched the OntoSpec methodology by endowing it with a new resource,
the DOLCE top-level ontology defined at the LOA (IST-CNR, Trento, Italy). The
goal of this integration is to provide modellers with additional help in
structuring application ontologies, while maintaining independence
vis-\`{a}-vis formal representation languages. In this report, we first provide
an overview of the OntoSpec methodology's general principles and then describe
the DOLCE re-engineering process. A complete version of DOLCE-OS (i.e. a
specification of DOLCE in the semi-informal OntoSpec language) is presented in
an appendix
Spatial Reference in Rongga (ISO 639-3: ror), Balinese (ISO 639-3: ban), and Indonesian (ISO 639-3: ind)
Many scholars have proposed concepts relevant to spatial reference. Herskovits (1982) proposed that the topological concepts support, contiguity and containment are basic in English, while Levinson et al.'s (2003) examination of nine unrelated languages revealed that the concept attachment is primary. Neither of these proposals is confirmed in Rongga, Balinese, and Indonesian. My empirical and experimental investigation of these languages showed that the concept expectedness governs the use of topological prepositions in the languages. Non-topologically, it has long been claimed that a relative frame of reference is universal. This claim is also not confirmed in this study. My non-topological relation study reveals that Rongga and Balinese use a landmark system, while Indonesian practices a relative system. The Balinese landmark system changes to an absolute system when speakers leave the island. In short, this study reveals that previous proposals on the concepts relevant to spatial reference are not universally supported
A survey of qualitative spatial representations
Representation and reasoning with qualitative spatial relations is an important problem in artificial intelligence and has wide applications in the fields of geographic information system, computer vision, autonomous robot navigation, natural language understanding, spatial databases and so on. The reasons for this interest in using qualitative spatial relations include cognitive comprehensibility, efficiency and computational facility. This paper summarizes progress in qualitative spatial representation by describing key calculi representing different types of spatial relationships. The paper concludes with a discussion of current research and glimpse of future work
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