Geography Reference
In-Depth Information
data, because we are dealing with huge number of objects (around 300 buildings).
Therefore it is crucial to keep the memory size of models of particular buildings and
objects as low as possible. Changing of the graphical representation together with
the collapsing of the shape of objects, are therefore used within the process of
modeling.
The fourth rule deals with the purposes depending on user
s
needs are defined as needs obtained from historian experts of the Terez
´
n Memorial
combined with the knowledge of GIS experts from University of West Bohemia.
The combined user requirements are as follows:
'
s needs. The user
'
To create a model of the Large and Small Fortress of Terez´n in the state of the
art at the end of the 2nd WW including buildings inside and outside of the city
and also the fortification around the fortress;
Buildings should be divided into two groups according to the importance of
a particular building during the period of interest. Thus there are two groups of
buildings. The first group is a group of so called “important” buildings. It
consists of buildings of a military purpose (like barracks, hospitals and so on)
or of buildings which were generally important (like a church, a water tower or
a kitchen). Other buildings are marked as important under the conditions that
momentous people lived or were imprisoned in such buildings or remarkable
events took a place there (that means e.g. cells, theater, morgue, music pavilion).
And the second group of buildings is group of “unimportant” buildings, which
are the others. Important objects will be modeled in higher level of detail than
the unimportant ones. But even for the important ones, no interior will be
modeled;
To enable visitors of Terez
´
n Memorial to obtain information about a particular
building, a person or a place directly from the visualized model at kiosks, placed
in the area of the Terez
´
n Memorial.
The Evolution of Works on Creation of 3D Models
It is obvious from the user requirements that we are dealing with the large amount
of data which need to be processed and subsequently modeled. It follows that the
complexity of the model is great and therefore it is crucial to involve a principle that
reduce the amount of data. We have chosen the Level of Detail principle described
at the beginning of chapter
Modeling of buildings of Terez´n Fortresses
. We have
created hierarchical data structure containing three levels: LOD1, LOD2, LOD3
(LOD0 is not necessary for the visualization purposes). In this place it has to be said
that the LOD3 for building which are not important isn
t the same as it is applied to
the important ones, which is derived from CityGML standard. Let
'
s mark the
'
Fig. 1 (continued) (
lower part
); (d, e) Comparison of simple (
left side
) and advanced (
right side
)
grass texture with identical pixel size (this view represents almost horizontal look over a cavalier)
