Geography Reference
In-Depth Information
model was done by textures. The impression from such a model is very good, the
model constitutes buildings and it
is easy to distinguish particular parts of
a building.
The all mentioned drafts applied on a window can be seen in Fig.
1b
(from left to
right, are drafts one to three).
Modeling of Terez´n
'
s Fortification
As mentioned above, the main aim of the model is to make a portrait of events
taking place in the period of the Second World War. At that time the fortification
was no more used for military purposes because it had become obsolete long time
before. Nevertheless, the fortification was still useful when the fortress acts as the
prison and the ghetto. Today the fortification plays no role in keeping enemies
outside or inside. Despite that, the fortification is still essential part of the Terez´n
city and is considered as a historical and technical heritage.
The fortification did not play any important role in the Second World War and
there are no descriptive data related to it. The main reason for modelling the
fortification is just to make an impression of a fortified city. So, from the modeling
point of view, the fortification falls into the “unimportant” group of objects and it
can be considerably generalized.
There are two main sources of spatial data regarding fortification. Plenty of
historical documents and plans depicting the fortification system is the first source.
They contain information important for modeling (e. g. shape of the fortification,
earthworks) but also for our purposes useless information describing invisible
underground, casemates and so on. The second source is an actual state of the
fortification. In spite of damages to the fortification that has been made so far, it is
possible to recover the historical state of the fortification. Of course, some back-
ground knowledge of the bastion fortification system is necessary.
A contract for licensing an already-made 3D model of fortification has been
assigned. The model is based on historical documents and plans, like in Popelka and
Brychtov´ (
2012
). Because the original model was too detailed, it was generalized
to a reasonable level. In order to keep a consistent appearance with the rest of a city
model, only the geometry of the model is used.
Unlike the buildings, the fortification is modeled in one LOD only. There are
three reasons for it:
The fortification is a very large object. It is not a rare situation in which one part
of the fortification is very close to an observer (potentially requiring higher
LOD), whereas some other part is far from the observer (requiring lower LOD)
in the same time. Thus, if the LODs were used, the fortification would have to be
divided in several parts for which different LODs could be applied.
Bastions, together with curtains, form a continuous fortification line around the
whole fortress. The profiles of curtains and bastions are linked together and there
