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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004
Geographical objects are grouped into 3 classes (Fig. 12):
|. public and craftsmen buildings (sacred buildings,
stod, gymnasium, thermal baths, public services
buildings and infrastructures);
2. residential buildings (building units characterized by
decorative, functional and typological features );
3. streets (main and secondary constituting the layout of
the city).
Meters
Fig. 12 - Classes of geographical objects
Streets layout is hierarchical relevant as it is the connection
element between other areas (all other features).
The information relating to the upper enumerated areas are
connected, in the database, to streets that are crossed from.
Every street is mainly defined by a code and a name (that was
attributed by archaeologists or public owner).
The code is constituted by two couple of integers numbers, the
first specify the theme, the second the class, so the whole code
field exists in a domain of integer numbers.
Every class comprises the set of different parts in which a street
is divided, so every part constitutes recognizing element of the
areas that are crossed by.
A code is associated to every part of these.
Public and private buildings, and their open spaces, constitute
geographical elements which are connected with specific
information, regarding building reference types, spatial
distributive features, the presence of decorative elements
(mosaics, frescoes and other artistic elements), the type of use,
the stages of constructions (deriving from specific
archaeological studies), etc.
All this entities are defined by a code and a name.
Also in this case the code is constituted by two couple of
numbers: the first specifying the theme (01 — public buildings
and services, 02 — residential buildings), the second specifying
the class. In order to better describe each building, it also exists
a database with room data coded by a couple of numbers.
The definition of the structure of information system is
finalized to facilitate the information management, during the
navigation, through the software .
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4. POCKETARCHEONAV - THE MULTIMEDIA
GUIDE
The multimedia guide has been realized using Enhanced Visual
Basic” for Pocket PC 2002 and MapInfo MapX Mobile SDK”.
MapX Mobile SDK gives the application all the base functions
to manage base maps and the geodatabase.
So the Pocket ArcheoNav has got the main functions of a
geographic client to query the database and to change the
thematic representation of geographical objects (the features).
The support for managing GPS data was written, by the
research group, in order to manage the data received by GPS
units.
After the launch and map loading, the application goes in
moving map state when the GPS button is pressed.
When the visitor goes around and enter into any feature area,
the software performs a simple calculation to check if the
visitor has never been in this area, and in affirmative case the
guide message starts. To be sure that a point is really inside an
feature area, a subroutine has been written that may calculate
both the average value on a predefined number of points,
received by the GPS unit, or the percentage of a predefined
number of point that fall inside the feature area. The most
suitable. way to estimate the visitor position is through thc
second method: the position is given good if the 80% of 5
points are inside a feature, but the percentage value or the
number of points may be changed.
The PocketPc used for the experimentation is a HP IPAQ 5450
with 64 MB of RAM (Arm Xscale processor), equipped with an
expansion memory SD card of 256 MB. The speed of the
processor is of main importance for this kind of application.
File View Tools
EI
Fig. 13 — The main screen of the software application
The geodatabase is built using ArcGIS® then exported in
MapInfo? by which is created the MapInfo geoset, that is also
supported by MapX Mobile SDK*.
Sound data files are converted in MP3 format to save space.
The database has a minimal dimension and structure in order to
save memory and to improve the execution speed of the
application.
Every point is received. by the GPS, in geographical
coordinates in WGS84 datum and is converted by a subroutine