CoastGIS’99: geomatics and coastal environment
environmental protection), the perimeters under the responsibility of
administrative authorities or technical services as well as management
units and technical zonings. In face of the sheer extent of the task, this
study did not prove to be exhaustive, but an attempt was made to look
for the main texts and to propose an in-depth study of demarcated territories so that the principles of construction were revealed.
The first difficulty is to have complete and up to date information.
The interpretation of juridical texts is not always obvious and jurisprudence also plays a role. Various studies relative to the law of the sea
and of the coast were analysed as well as regional legal monographs which contained clear and updated interpretations regarding fishing regulations (Slomp, 1995; Cidam, 1999). Different legal text servers were
also consulted and a jurist was asked to achieve a complementary study
(Tierny, 1998).
On analysing the construction methods, it was possible to identify the
“elementary bricks" (lines or polygons) and to distinguish between the
reference elements, shared by various boundaries and zones, and the data
belonging to one given regulation. These elementary bricks were then
confronted with the georeferenced data already available in map or
digital form. The detailed inventory of the types of boundaries and
zones, definitions, construction modalities, data sources, gaps, existing or foreseeable requirements, problems of coherence, and product
proposals are included in the Shom-Ifremer working group report
(Allain et al., 1999 b).
The next step is to organize, with these elementary bricks, the logical
and hierarchical generation of constructions in such a way as to keep
the whole set-up as coherent as possible. Some zones can be considered
totally autonomous. They may also result from the combination of
other zones or buffering operations. But in most cases, zones are determined by a reference to a landward, seaward and lateral boundaries. In
order to facilitate operational use, and to set up data conceptual models
structuring the hierarchical construction, functional entities corresponding to the most common uses, and derived from an extensive
consultation practice, have to be highlighted.
The updating process seems essential in this thematic domain as the
data are strongly interdependent and there may well be numerous reasons for updating: publication of new texts, interpretation errors and
jurisprudence, non-stability of reference objects, temporal variability
of construction elements...
Generation of geometric elements
The sources of available digital data are widely dispersed and sometimes
there are formats which are specific to an organization which renders
the problem of information exchange even more complex. The marine
charts and the French topographical land maps are not drawn up using
the same projections and do not use the same geodesic systems or the
same ellipsoids. Although these problems may be overcome theoretically, the transformation tools are not available in standard software,
274
environmental protection), the perimeters under the responsibility of
administrative authorities or technical services as well as management
units and technical zonings. In face of the sheer extent of the task, this
study did not prove to be exhaustive, but an attempt was made to look
for the main texts and to propose an in-depth study of demarcated territories so that the principles of construction were revealed.
The first difficulty is to have complete and up to date information.
The interpretation of juridical texts is not always obvious and jurisprudence also plays a role. Various studies relative to the law of the sea
and of the coast were analysed as well as regional legal monographs which contained clear and updated interpretations regarding fishing regulations (Slomp, 1995; Cidam, 1999). Different legal text servers were
also consulted and a jurist was asked to achieve a complementary study
(Tierny, 1998).
On analysing the construction methods, it was possible to identify the
“elementary bricks" (lines or polygons) and to distinguish between the
reference elements, shared by various boundaries and zones, and the data
belonging to one given regulation. These elementary bricks were then
confronted with the georeferenced data already available in map or
digital form. The detailed inventory of the types of boundaries and
zones, definitions, construction modalities, data sources, gaps, existing or foreseeable requirements, problems of coherence, and product
proposals are included in the Shom-Ifremer working group report
(Allain et al., 1999 b).
The next step is to organize, with these elementary bricks, the logical
and hierarchical generation of constructions in such a way as to keep
the whole set-up as coherent as possible. Some zones can be considered
totally autonomous. They may also result from the combination of
other zones or buffering operations. But in most cases, zones are determined by a reference to a landward, seaward and lateral boundaries. In
order to facilitate operational use, and to set up data conceptual models
structuring the hierarchical construction, functional entities corresponding to the most common uses, and derived from an extensive
consultation practice, have to be highlighted.
The updating process seems essential in this thematic domain as the
data are strongly interdependent and there may well be numerous reasons for updating: publication of new texts, interpretation errors and
jurisprudence, non-stability of reference objects, temporal variability
of construction elements...
Generation of geometric elements
The sources of available digital data are widely dispersed and sometimes
there are formats which are specific to an organization which renders
the problem of information exchange even more complex. The marine
charts and the French topographical land maps are not drawn up using
the same projections and do not use the same geodesic systems or the
same ellipsoids. Although these problems may be overcome theoretically, the transformation tools are not available in standard software,
274