A pictorial query language for geographic features in an object-oriented environment
F Ferri, F Massari, M Rafanelli - Journal of Visual Languages & Computing, 1999 - Elsevier
In this paper, a visual algebra and the relative pictorial query language (PQL) for geographic
information systems (GIS) are proposed and discussed. The base data structure of the object
oriented model for geographical data is defined and the symbolic features used in the PQL
are described. The algebra operators are formally defined, besides their properties and
applicability. The use of the symbolic features to express the queries is illustrated, as well as
the possible pictorial operations are considered. The used interface is part of the Scenario …
information systems (GIS) are proposed and discussed. The base data structure of the object
oriented model for geographical data is defined and the symbolic features used in the PQL
are described. The algebra operators are formally defined, besides their properties and
applicability. The use of the symbolic features to express the queries is illustrated, as well as
the possible pictorial operations are considered. The used interface is part of the Scenario …
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