2 GeoMTGM
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2.3 Geographical Multimedia Temporal Graphical Model
The geographical multimedia temporal graphical model (GeoMTGM) is a logical
model for the representation of geographic information. More precisely, it enriches
MTGM with the constructs necessary for representing information with both the
entity-based and the field-based models.
2.3.1 GeoMTGM at Work
In this section, we describe the main features of GeoMTGM through the use of an
example.
A GeoMTGM Database
As an example to illustrate the characteristics of GeoMTGM, we propose to model
the history of a highway using semistructured data. In particular, we consider the
Highway A1 of the Italian highway network, which has the following general features:
• It starts in Milan and ends in Naples.
• It is 754 km long and has been built in several phases: first, the route from Milan
to Parma was opened in 1954, then in 1964 the route from Florence to Rome
became operative. Finally, the segment from Rome to Naples was added and
opened in 1966.
• It has a set of toll stations, where each toll station has a number of payment
points and a number of telepass points.
• It has several intersections with other highways.
• Sometimes, accidents occur at several points on the highway route and the highway can eventually be blocked or suffer reduced traffic flow; finally, maintenance
work can be present along the route of the highway with consequent traffic flow
reduction.
All these features can be represented in a GeoMTGM graph as shown in Fig. 2.1.
In particular, the temporal evolution of some of the properties of the highway can
also be represented, for example, the evolution of its route that has been built in
three separate phases or the different events that can occur along the highway, such
as accidents, maintenance work, strikes, and so on.
Figure 2.1 shows the schema of a GeoMTGM graph containing information
about the A1 Highway, while Figs. 2.2 and 2.3, show a possible instance of it. As
usual in semistructured data models, (part of) the schema and (part of) the instance
of a database are represented in a similar way through graphs.
In GeoMTGM the entities of the modeled reality are represented through complex nodes (depicted as rectangles). In particular, there is a special kind of complex
node, named geographical complex node (geoComplex node in short), that represents
geographical entities (depicted as dashed rectangles). For example, in Fig. 2.1 Owner
19
2.3 Geographical Multimedia Temporal Graphical Model
The geographical multimedia temporal graphical model (GeoMTGM) is a logical
model for the representation of geographic information. More precisely, it enriches
MTGM with the constructs necessary for representing information with both the
entity-based and the field-based models.
2.3.1 GeoMTGM at Work
In this section, we describe the main features of GeoMTGM through the use of an
example.
A GeoMTGM Database
As an example to illustrate the characteristics of GeoMTGM, we propose to model
the history of a highway using semistructured data. In particular, we consider the
Highway A1 of the Italian highway network, which has the following general features:
• It starts in Milan and ends in Naples.
• It is 754 km long and has been built in several phases: first, the route from Milan
to Parma was opened in 1954, then in 1964 the route from Florence to Rome
became operative. Finally, the segment from Rome to Naples was added and
opened in 1966.
• It has a set of toll stations, where each toll station has a number of payment
points and a number of telepass points.
• It has several intersections with other highways.
• Sometimes, accidents occur at several points on the highway route and the highway can eventually be blocked or suffer reduced traffic flow; finally, maintenance
work can be present along the route of the highway with consequent traffic flow
reduction.
All these features can be represented in a GeoMTGM graph as shown in Fig. 2.1.
In particular, the temporal evolution of some of the properties of the highway can
also be represented, for example, the evolution of its route that has been built in
three separate phases or the different events that can occur along the highway, such
as accidents, maintenance work, strikes, and so on.
Figure 2.1 shows the schema of a GeoMTGM graph containing information
about the A1 Highway, while Figs. 2.2 and 2.3, show a possible instance of it. As
usual in semistructured data models, (part of) the schema and (part of) the instance
of a database are represented in a similar way through graphs.
In GeoMTGM the entities of the modeled reality are represented through complex nodes (depicted as rectangles). In particular, there is a special kind of complex
node, named geographical complex node (geoComplex node in short), that represents
geographical entities (depicted as dashed rectangles). For example, in Fig. 2.1 Owner