Results 1  10
of
21
A Foundation for Representing and Querying Moving Objects
, 2000
"... Spatiotemporal 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 timedependent geometries, including those changing continuously which describe moving objects. Two fundamental abstractions are moving ..."
Abstract

Cited by 152 (35 self)
 Add to MetaCart
Spatiotemporal 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 timedependent geometries, including those changing continuously which describe moving objects. Two fundamental abstractions are moving point and moving region, describing objects for which only the timedependent position, or position and extent, are of interest, respectively. We propose to represent such timedependent 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 timedependent 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 nontemporal 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 spatiotemporal 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 spatiotemporal DBMS extension.
RealmBased Spatial Data Types: The ROSE Algebra
 VLDB JOURNAL
, 1995
"... Spatial data types or algebras for database systems should (1) be fully general, that is, closed under set operations, (2) have formally defined semantics, (3) be defined in terms of finite representations available in computers, (4) offer facilities to enforce geometric consistency of related spat ..."
Abstract

Cited by 42 (3 self)
 Add to MetaCart
Spatial data types or algebras for database systems should (1) be fully general, that is, closed under set operations, (2) have formally defined semantics, (3) be defined in terms of finite representations available in computers, (4) offer facilities to enforce geometric consistency of related spatial objects, and (5) be independent of a particular DBMS data model, but cooperate with any. We present an algebra that uses realms as geometric domains underlying spatial data types. A realm, as a general database concept, is a finite, dynamic, userdefined structure underlying one or more system data types. Problems of numerical robustness and topological correctness are solved within and below the realm layer so that spatial algebras defined above a realm have very nice algebraic properties. Realms also interact with a DMBS to enforce geometric consistency on object creation or update. The ROSE algebra is defined on top of realms and offers general types to represent point, line, and region features, together with a comprehensive set of operations. It is described within a polymorphic type system and interacts with a DMBS data model and query language through an abstract object model interface. An example integration of ROSE into the objectoriented data model 02 and its query language is presented.
Implementation of the ROSE Algebra: Efficient Algorithms for RealmBased Spatial Data Types
 PROC. OF THE 4TH INTL. SYMPOSIUM ON LARGE SPATIAL DATABASES
, 1995
"... The ROSE algebra, defined earlier, is a system of spatial data types for use in spatial database systems. It offers data types to represent points, lines, and regions in the plane together with a comprehensive set of operations; semantics of types and operations have been formally defined. Values ..."
Abstract

Cited by 37 (14 self)
 Add to MetaCart
The ROSE algebra, defined earlier, is a system of spatial data types for use in spatial database systems. It offers data types to represent points, lines, and regions in the plane together with a comprehensive set of operations; semantics of types and operations have been formally defined. Values of these data types have a quite general structure, e.g. an object of type regions may consist of several polygons with holes. All ROSE objects are realmbased which means all points and vertices of objects lie on an integer grid and no two distinct line segments of any two objects intersect in their interior. In this paper we describe the implementation of the ROSE algebra, providing data structures for the types and new realmbased geometric algorithms for the operations. The main techniques used are (parallel) traversal of objects, planesweep, and graph algorithms. All algorithms are analyzed with respect to their worst case time and space requirements. Due to the realm properties, these algorithms are relatively simple, efficient, and numerically completely robust. All data structures and algorithms have indeed been implemented in the ROSE system; the Modula2 source code is freely available from the authors for study or use.
Modeling and Querying Moving Objects in Networks
 VLDB J
, 2004
"... Moving Objects Databases have become an important research issue in recent years. For modeling and querying moving objects, there exists a comprehensive framework of abstract data types to describe objects moving freely in the 2D plane, providing data types such as moving point or moving region. ..."
Abstract

Cited by 35 (7 self)
 Add to MetaCart
Moving Objects Databases have become an important research issue in recent years. For modeling and querying moving objects, there exists a comprehensive framework of abstract data types to describe objects moving freely in the 2D plane, providing data types such as moving point or moving region. However, in many applications people or vehicles move along transportation networks.
Algorithms for Moving Objects Databases
"... Whereas earlier work on spatiotemporal databases generally focused on geometries changing in discrete steps, the emerging area of moving objects databases supports geometries changing continuously. Two important abstractions are moving point and moving region, modeling objects for which only the ti ..."
Abstract

Cited by 35 (10 self)
 Add to MetaCart
Whereas earlier work on spatiotemporal databases generally focused on geometries changing in discrete steps, the emerging area of moving objects databases supports geometries changing continuously. Two important abstractions are moving point and moving region, modeling objects for which only the timedependent position, or also the shape and extent are relevant, respectively. Examples of the first kind of moving entity are all kinds of vehicles, aircraft, people, or animals; of the latter hurricanes, forest res, forest growth, or oil spills in the sea. The goal is to develop data models and query languages as well as DBMS implementations supporting such entities, enabling new kinds of database applications. In earlier work we have proposed an approach based on abstract data types. Hence, moving point or moving region are viewed as data types with suitable operations. For example, a moving point might be projected into the plane, yielding a curve, or a moving region be mapped to a function describing the development of its size, yielding a realvalued function. A careful design of a system of types and operations (an algebra) has been presented, emphasizing completeness, closure, consistency and genericity. This design was given at an abstract level, defining, for example, geometries in terms of infinite point sets. In the next step, a discrete model was presented, o ering nite representations and data structures for all the types of the abstract model. The present paper provides the final step towards implementation by studying and developing systematically algorithms for (a large subset of) the operations. Some of them are relatively straightforward; others are quite complex. Algorithms are meant to be used in a database context; we also address...
Explicit Graphs in a Functional Model for Spatial Databases
 IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING
, 1994
"... Observing that networks are ubiquitous in applications for spatial databases, we define a new data model and query language that especially supports graph structures. This model integrates concepts of functional data modeling with ordersorted algebra. Besides object and data type hierarchies grap ..."
Abstract

Cited by 28 (9 self)
 Add to MetaCart
Observing that networks are ubiquitous in applications for spatial databases, we define a new data model and query language that especially supports graph structures. This model integrates concepts of functional data modeling with ordersorted algebra. Besides object and data type hierarchies graphs are available as an explicit modeling tool, and graph operations are part of the query language. Graphs have three classes of components, namely nodes, edges, and explicit paths. These are at the same time object types within the object type hierarchy and can be used like any other type. Explicit paths are useful because “real world ” objects often correspond to paths in a network. Furthermore, a dynamic generalization concept is introduced to handle heterogeneous collections of objects in a query. In connection with spatial data types this leads to powerful modeling and querying capabilities for spatial databases, in particular for spatially embedded networks such as highways, rivers, public transport, and so forth. We use multilevel ordersorted algebra as a formal framework for the specification of our model. Roughly spoken, the first level algebra defines types and operations of the query language whereas the second level algebra defines kinds (collections of types) and type constructors as functions between kinds and so provides the types that can be used at the first level.
Managing Moving Objects on Dynamic Transportation Networks
 Proc. of the 16th Intl. Conf. on Scientific and Statistical Database Management (SSDBM, Santorini Island
, 2004
"... databases (MOD) is the modeling of moving objects. In this paper, a new moving objects database model, Moving Objects on Dynamic Transportation Networks (MODTN), is proposed. In MODTN, moving objects are modeled as moving graph points which move only within predefined transportation networks. To exp ..."
Abstract

Cited by 23 (5 self)
 Add to MetaCart
databases (MOD) is the modeling of moving objects. In this paper, a new moving objects database model, Moving Objects on Dynamic Transportation Networks (MODTN), is proposed. In MODTN, moving objects are modeled as moving graph points which move only within predefined transportation networks. To express general events of the system, such as traffic jams, temporary constructions, insertion and deletion of junctions or routes, the underlying transportation networks are modeled as dynamic graphs so that the state and the topology of the graph system at any time instant can be tracked and queried. Besides, to track the location of network constrained moving objects, a location update mechanism is provided, and the corresponding uncertainty management issues are analyzed.
Secondo: An extensible dbms platform for research prototyping and teaching
 In ICDE
, 2005
"... ..."
Supporting uncertainty in moving objects in network databases
 in GIS, 2005
"... The management of moving objects has been intensively studied in the recent years. A wide and increasing range of database applications has to deal with spatial objects whose position changes continuously over time, called moving objects. Due to the continuous and unpredictable nature of the movemen ..."
Abstract

Cited by 12 (1 self)
 Add to MetaCart
The management of moving objects has been intensively studied in the recent years. A wide and increasing range of database applications has to deal with spatial objects whose position changes continuously over time, called moving objects. Due to the continuous and unpredictable nature of the movements, they cannot be precisely stored in a database, and therefore objects ’ positions are sampled, and between these sampled positions interpolation is used. This sampling/interpolation approach results in uncertainty in the objects ’ positions in the whole trajectory of the moving objects. In this paper, we try to analyze this problem about uncertainty when the movement is restricted to a network. Examples of such movements are cars in highways and trains in railroads. The uncertainty problem is simpler in such cases compared to the free movement in 2dimensional space. We describe the geometry of the uncertain trajectories of the objects with movement constrained to networks, an extension to the framework in [18, 16] to support uncertainty, as well as some implementation considerations using Secondo, an extensible database system that supports nonstandard applications.
Modeling Temporally Variable Transportation Networks
 in Proc. of DASFAA
, 2004
"... In this paper, a StateBased Dynamic Transportation Network (SBDTN) model is presented, which can be used to describe the spatiotemporal aspect of temporally variable transportation networks. The basic idea of this model is to associate a temporal attribute to every node or edge of the graph sys ..."
Abstract

Cited by 10 (2 self)
 Add to MetaCart
In this paper, a StateBased Dynamic Transportation Network (SBDTN) model is presented, which can be used to describe the spatiotemporal aspect of temporally variable transportation networks. The basic idea of this model is to associate a temporal attribute to every node or edge of the graph system so that state changes (such as traffic jams and blockages caused by temporary constructions) and topology changes (such as insertion and deletion of nodes or edges) can be expressed. Since the changes of the graph system are discrete, the temporal attribute can be expressed as a series of temporal units and each temporal unit describes one single state of the node or edge during a certain period of time. The data model is given as a collection of data types and operations which can be plugged as attribute types into a DBMS to obtain a complete data model and query language.