``Putting Channels on the Map'': a formal semiotics for (Geo)graphical Information Systems
Abstract
(Last changes Febr-22 1996)
How do agents understand graphical representations of spatial information, and
what are the mathematical properties of a formal semiotics for representation
systems in general? We provide an account based on a new mathematical notion of
information channels (Channel Theory) which are available to agents and which are
robust enough to support imperfect information flow in practical contexts. The
paper presents a formal semiotics for a wide class of graphical representations in terms of
a modified version of Channel Theory. The resulting system is applicable to the
semantic analysis of representations and algorithms in the ``Arc/Info '' Geographical
Information System (GIS). Special characteristics of ``map-like representations" (MLRs)
are discussed, and two central issues are raised: their verisimilitude or ``approximation
to truth'', and the variety of errors which they often exhibit. In response, an ``approximation'' semantics for MLRs is provided, which relies on a formal account
of error based on Channel Theory as a general theory of representation. The formalism
is intended as the foundation of a rigorous logical approach to graphical information systems -- just the kind of common resource sorely needed in the emerging interdisciplinary
field of data visualization, involving Diagrammatic Reasoning, Mental Imagery,
Visual, Spatial, and Geographical Information Systems (GIS), ``Virtual Reality'' and HCI in general. The paper also raises some important philosophical issues
about the nature of representation systems.
(This research is supported by the Leverhulme Trust. The ``map semantics''
homepage can be found at WWW-Homepage)
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Hansgeorg Schlichtmann [1991], Plan Information and its Retrieval in Map Interpretation:
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Oliver Lemon: mailto: lemonoj@cs.man.ac.uk
Ian Pratt: ipratt@cs.man.ac.uk
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