Abstract: This paper describes a unified framework for the problems of modelling and processing spatial entities. We propose a general definition of spatial objects, and show that the different types of spatial data can be expressed as particular cases of this definition. Furthermore, we present a taxonomy for the various types of GIS operations, defined in terms of the properties of this definition. Our goal is to argue that GIS data types and operations can be defined based on a single formal notion, which encapsulates the GIS concepts of both continuous fields and discrete features, with important consequences for system and interface design, interoperabilty issues and language proposal.

Resumo: Este artigo define objetos geográficos, que servem como base formal para a definição dos outros tipos de dados geográficos, englobando tanto geo-campos quanto geo-objetos. Este artigo não aborda implementação e sim a modelagem matemática destes objetos geográficos. São propostas quatro classificações possíveis de objetos geográficos: simples e homogênea, composta e homogênea, simples e não homogênea e composta e não-homogênea. São definidas operações sobre objetos geográficos, que podem ser atômicas ou compostas. A idéia é que operações complexas possam ser definidas a partir de operações atômicas. O artigo cita algumas operações, como: Alteração/Consulta de atributos, Relacionamento Espacial, Distância, etc.

Abstract: Geographic representation has become more complex through time as researchers have added new concepts, leading to apparently endless proliferation and creating a need for simplification. We show that many of these concepts can be derived from a single foundation that we term the atomic form of geographic information. The familiar concepts of continuous fields and discrete objects can be derived under suitable rules applied to the properties and values of the atomic form. Fields and objects are further integrated through the concept of phase space, and in the form of field objects. A second atomic concept is introduced, termed the geo-dipole, and shown to provide a foundation for object fields, metamaps, and the association classes of object-oriented data modelling. Geographic dynamics are synthesized in a three-dimensional space defined by static or dynamic object shape, the possibility of movement, and the possibility of dynamic internal structure. The atomic form also provides a tentative argument that discrete objects and continuous fields are the only possible bases for geographic representation.