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39
A Foundation for Representing and Querying Moving Objects
, 2000
"... Spatio-temporal databases deal with geometries changing over time. The goal of our work is to provide a DBMS data model and query language capable of handling such time-dependent geometries, including those changing continuously which describe moving objects. Two fundamental abstractions are moving ..."
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Cited by 200 (39 self)
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Spatio-temporal databases deal with geometries changing over time. The goal of our work is to provide a DBMS data model and query language capable of handling such time-dependent geometries, including those changing continuously which describe moving objects. Two fundamental abstractions are moving point and moving region, describing objects for which only the time-dependent position, or position and extent, are of interest, respectively. We propose to represent such time-dependent geometries as attribute data types with suitable operations, that is, to provide an abstract data type extension to a DBMS data model and query language. This paper presents a design of such a system of abstract data types. It turns out that besides the main types of interest, moving point and moving region, a relatively large number of auxiliary data types is needed. For example, one needs a line type to represent the projection of a moving point into the plane, or a "moving real" to represent the time-dependent distance of two moving points. It then becomes crucial to achieve (i) orthogonality in the design of the type system, i.e., type constructors can be applied uniformly, (ii) genericity and consistency of operations, i.e., operations range over as many types as possible and behave consistently, and (iii) closure and consistency between structure and operations of non-temporal and related temporal types. Satisfying these goals leads to a simple and expressive system of abstract data types that may be integrated into a query language to yield apowerful language for querying spatio-temporal data, including moving objects. The paper formally defines the types and operations, offers detailed insight into the considerations that went into the design, and exempli es the use of the abstract data types using SQL. The paper o ers a precise and conceptually clean foundation for implementing a spatio-temporal DBMS extension.
Indexing moving points
, 2003
"... We propose three indexing schemes for storing a set S of N points in the plane, each moving along a linear trajectory, so that any query of the following form can be answered quickly: Given a rectangle R and a real value t; report all K points of S that lie inside R at time t: We first present an in ..."
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Cited by 184 (11 self)
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We propose three indexing schemes for storing a set S of N points in the plane, each moving along a linear trajectory, so that any query of the following form can be answered quickly: Given a rectangle R and a real value t; report all K points of S that lie inside R at time t: We first present an indexing structure that, for any given constant e> 0; uses OðN=BÞ disk blocks and answers a query in OððN=BÞ 1=2þe þ K=BÞ I/Os, where B is the block size. It can also report all the points of S that lie inside R during a given time interval. A point can be inserted or deleted, or the trajectory of a point can be changed, in Oðlog 2 B NÞ I/Os. Next, we present a general approach that improves the query time if the queries arrive in chronological order, by allowing the index to evolve over time. We obtain a tradeoff between the query time and the number of times the index needs to be updated as the points move. We also describe an indexing scheme in which the number of I/Os required to answer a query depends monotonically on the difference between the query time stamp t and the current time. Finally, we develop an efficient indexing scheme to answer approximate
A Data Model and Data Structures for Moving Objects Databases
, 1999
"... We consider spatio-temporal databases supporting spatial objects with continuously changing position and extent, termed moving objects databases. We formally define a data model for such databases that includes complex evolving spatial structures such as line networks or multi-component regions w ..."
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Cited by 149 (29 self)
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We consider spatio-temporal databases supporting spatial objects with continuously changing position and extent, termed moving objects databases. We formally define a data model for such databases that includes complex evolving spatial structures such as line networks or multi-component regions with holes. The data model is given as a collection of data types and operations which can be plugged as attribute types into any DBMS data model (e.g. relational, or object-oriented) to obtain a complete model and query language. A particular novel concept is the sliced representation which represents a temporal development as a set of units, where unit types for spatial and other data types represent certain "simple" functions of time. We also show how the model can be mapped into concrete physical data structures in a DBMS environment. 1 Introduction A wide and increasing range of database applications has to deal with spatial objects whose position and/or extent changes over time...
On the Generation of Spatiotemporal Datasets
, 1999
"... . An efficient benchmarking environment for spatiotemporal access methods should at least include modules for generating synthetic datasets, storing datasets (real datasets included), collecting and running access structures, and visualizing experimental results. Focusing on the dataset reposito ..."
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Cited by 118 (12 self)
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. An efficient benchmarking environment for spatiotemporal access methods should at least include modules for generating synthetic datasets, storing datasets (real datasets included), collecting and running access structures, and visualizing experimental results. Focusing on the dataset repository module, a collection of synthetic data that would simulate a variety of real life scenarios is required. Several algorithms have been implemented in the past to generate static spatial (point or rectangular) data, for instance, following a predefined distribution in the workspace. However, by introducing motion, and thus temporal evolution in spatial object definition, generating synthetic data tends to be a complex problem. In this paper, we discuss the parameters to be considered by a generator for such type of data, propose an algorithm, called "Generate_Spatio_Temporal_Data" (GSTD), which generates sets of moving point or rectangular data that follow an extended set of distri...
Spatio-Temporal Predicates
- IEEE Transactions on Knowledge and Data Engineering
, 1999
"... AbstractÐThis paper investigates temporal changes of topological relationships and thereby integrates two important research areas: First, two-dimensional topological relationships that have been investigated quite intensively and, second, the change of spatial information over time. We investigate ..."
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Cited by 57 (15 self)
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AbstractÐThis paper investigates temporal changes of topological relationships and thereby integrates two important research areas: First, two-dimensional topological relationships that have been investigated quite intensively and, second, the change of spatial information over time. We investigate spatio-temporal predicates, which describe developments of well-known spatial topological relationships. A framework is developed in which spatio-temporal predicates can be obtained by temporal aggregation of elementary spatial predicates and sequential composition. We compare our framework with two other possible approaches: one is based on the observation that spatio-temporal objects correspond to three-dimensional spatial objects for which existing topological predicates can be exploited. The other approach is to consider possible transitions between spatial configurations. These considerations help to identify a canonical set of spatio-temporal predicates. Index TermsÐTime in geographic information, spatio-temporal data types, representation of spatio-temporal objects, changes of spatial predicates, developments of spatial objects. 1
Making space for time: issues in space-time data representation
- GeoInformatica
, 2001
"... Even with much activity over the past decade, including organized efforts on both sides of the Atlantic, the representation of both space and time in digital databases is still problematic and functional space-time systems have not gone beyond the limited prototype stage. Why is this the case? Why d ..."
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Cited by 53 (1 self)
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Even with much activity over the past decade, including organized efforts on both sides of the Atlantic, the representation of both space and time in digital databases is still problematic and functional space-time systems have not gone beyond the limited prototype stage. Why is this the case? Why did it take twenty years from the ®rst GIS for the for representation and analysis in the temporal, as well as the spatial dimension, to begin? I explore the answers to these questions by giving a historical overview of the development of space-time representation in the geographic information systems and database communities and a review of the most recent research. Within the context of this perspective, I also question what seems to be a spirit of self-accusation in which the lack of functional space-time systems has been discussed in the literature and in meetings of GIS researchers. I close by offering my own interpretation of current research issues on space-time data models and languages.
Developments in Spatio-Temporal Query Languages
, 1999
"... Integrating spatio-temporal data as abstract data types into already existing data models is a promising approach to creating spatio-temporal query languages. In this context, an important new class of queries can be identified which is concerned with developments of spatial objects over time, that ..."
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Cited by 37 (11 self)
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Integrating spatio-temporal data as abstract data types into already existing data models is a promising approach to creating spatio-temporal query languages. In this context, an important new class of queries can be identified which is concerned with developments of spatial objects over time, that is, queries ask especially for changes in spatial relationships. Based on a definition of the notion of spatio-temporal predicate we provide a framework which allows to build more and more complex predicates starting with a small set of elementary ones. These predicates can be well used to characterize developments. We show how these concepts can be realized within the relational data model. In particular, we demonstrate how SQL can be extended to enable the querying of developments.
Tripod: A Comprehensive System for the Management of Spatial and Aspatial Historical Objects
- In Proc. ACM-GIS, ACM Press
, 2001
"... (ii) a component-based design in which spatial, temporal and historical extensions are formalised incrementally, for subsequent use together or separately; (iii) compatibility with mainstream query processing frameworks for object databases; and (iv) the integration of the spatio-temporal proposal w ..."
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Cited by 11 (4 self)
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(ii) a component-based design in which spatial, temporal and historical extensions are formalised incrementally, for subsequent use together or separately; (iii) compatibility with mainstream query processing frameworks for object databases; and (iv) the integration of the spatio-temporal proposal with the ODMG standard. Spatio-temporal extensions to data models have been an active area of research for a number of years. To date, much of this work has focused on the relational data model, with object data models receiving far less consideration. Where descriptions of such object models do exist, there is currently a lack of systems which build upon these models to 1
The Honeycomb Model of Spatio-Temporal Partitions
- In Int. Workshop on Spatio-Temporal Database Management, LNCS 1678
, 1999
"... . We define a formal model of spatio-temporal partitions which can be used to model temporally changing maps. We investigate new applications and generalizations of operations that are well-known for static spatial maps. We then define a small set of operations on spatio-temporal partitions that are ..."
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Cited by 10 (4 self)
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. We define a formal model of spatio-temporal partitions which can be used to model temporally changing maps. We investigate new applications and generalizations of operations that are well-known for static spatial maps. We then define a small set of operations on spatio-temporal partitions that are powerful enough to express all these tasks and more. Spatio-temporal partitions combine the general notion of temporal objects and the powerful spatial partition abstraction into a new, highly expressive spatio-temporal data modeling tool. 1 Introduction The subject of this paper is the temporal evolution of maps. The metaphor of a map has turned out to be a fundamental and ubiquitous spatial concept in many spatially-oriented disciplines like geography and cartography as well as in computer-assisted systems like geographical informations systems (GIS), spatial database systems, and image database systems, but also simply for human's spatial orientation in everyday life. A map is a widely ...
ST USM: Bridging the Semantic Gap with a Spatio-Temporal Conceptual Model
, 2001
"... The representation of geospatial phenomena in databases is one of the key issues in applications like geo-marketing, environmental modeling, transportation planning and geology. For these geospatial applications, there is a need for abstract concepts that would bridge the conceptual gap between the ..."
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Cited by 6 (4 self)
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The representation of geospatial phenomena in databases is one of the key issues in applications like geo-marketing, environmental modeling, transportation planning and geology. For these geospatial applications, there is a need for abstract concepts that would bridge the conceptual gap between the real world and its spatio-temporal representation in the computer systems. To capture the semantics related to space and time in a conceptual schema, we propose an annotation-based approach that allows a database designer to focus first on the non-temporal and non-spatial aspects of the application, and subsequently augment the schema with spatio-temporal annotations. In this paper, we apply our annotation-based approach to the Unifying Semantic Model (USM) to propose the Spatio-Temporal Unifying Semantic Model (ST USM). ST USM is an upward-compatible, snapshot reducible, annotation-based spatio-temporal conceptual model that can comprehensively capture the semantics related to space and time without adding any new spatio-temporal constructs. We provide the formal semantics of ST USM via a mapping to conventional USM and constraints, from which the logical schema can be derived. We illustrate practical aspects related to our spatiotemporal design methodology with a hydrogeologic application at the United States Geological Survey (USGS) and a web-based design tool, thereby demonstrating simplicity and comprehensiveness to spatio-temporal conceptual modeling. 1
