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Accessing Geoenvironmental Data: From On-line to Expert Systems
Two wonderful tools are modifying our way of looking at geographical models:
stereoscopic TV, as it is currently used in Japan, for the public at large. Adapted to
GIS applications, it completely transforms our sight of a terrain model, for
instance in a flight simulator, or our impression of the town for an urbanist.
Virtual reality, rather different, works at another scale, possibly putting the
geographer inside his model, providing moreover an interaction with this one ..
3 BRIEF REMINDER OF 0.-0. TOOLS
A model named HBDS was developed in 1976, together with a complete system,
and many applications devoted specifically to GIS and oil exploration and
production, both these areas being deeply interconnected (Bouille, 1994a).
3.1 The "HBDS" model
HBDS is based on mathematical concepts: set theory, graph theory including
hypergraph, theory of categories, fuzzy set theory. It uses abstract data types
(a.d.t.), with six basic ones, and six extensions, respectively named:
class - attribute of class - links between classes, composing the skeleton,
object - attribute of object - links between objects, composing the
realizations,
•
hyperclass - hyperattribute -hyperlink, allowing group components,
embryo, - prototype, - structure, allowing the design of new families of
components.
We shall not detail these aspects which were published before in various papers.
3.2
The "HBDS" system kernel
The HBDS system is built on a multilayered architecture, composing the kernel,
and successively providing:
an indexed-sequential file system, supporting any level of indexes, the
only limit being the available disk space,
a virtual memory mechanism providing the system with the impress that
all data are resident in core memory, taking into account the tum-over,
and optimizing exchanges, possibly with a look-ahead approach,
an object-oriented database, based upon persistent abstract data types,
(protected, simultaneously shareable and distributed), accepting fuzzy
data
a list processing supporting an unlimited number of unlimited lists,
whose elements are abstract data types,
Accessing Geoenvironmental Data: From On-line to Expert Systems
Two wonderful tools are modifying our way of looking at geographical models:
stereoscopic TV, as it is currently used in Japan, for the public at large. Adapted to
GIS applications, it completely transforms our sight of a terrain model, for
instance in a flight simulator, or our impression of the town for an urbanist.
Virtual reality, rather different, works at another scale, possibly putting the
geographer inside his model, providing moreover an interaction with this one ..
3 BRIEF REMINDER OF 0.-0. TOOLS
A model named HBDS was developed in 1976, together with a complete system,
and many applications devoted specifically to GIS and oil exploration and
production, both these areas being deeply interconnected (Bouille, 1994a).
3.1 The "HBDS" model
HBDS is based on mathematical concepts: set theory, graph theory including
hypergraph, theory of categories, fuzzy set theory. It uses abstract data types
(a.d.t.), with six basic ones, and six extensions, respectively named:
class - attribute of class - links between classes, composing the skeleton,
object - attribute of object - links between objects, composing the
realizations,
•
hyperclass - hyperattribute -hyperlink, allowing group components,
embryo, - prototype, - structure, allowing the design of new families of
components.
We shall not detail these aspects which were published before in various papers.
3.2
The "HBDS" system kernel
The HBDS system is built on a multilayered architecture, composing the kernel,
and successively providing:
an indexed-sequential file system, supporting any level of indexes, the
only limit being the available disk space,
a virtual memory mechanism providing the system with the impress that
all data are resident in core memory, taking into account the tum-over,
and optimizing exchanges, possibly with a look-ahead approach,
an object-oriented database, based upon persistent abstract data types,
(protected, simultaneously shareable and distributed), accepting fuzzy
data
a list processing supporting an unlimited number of unlimited lists,
whose elements are abstract data types,