An Integrated 3D-GIS for an Inventory of the Historic Monuments ... 
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6.2 Organisation of the Descriptive and Attribute Information 
In particular, we can subdivide the descriptive information into the following elements: 
• Line and area symbols for geometric presentations 
• Point symbols which can be summarised in libraries (cell library) 
• Attiibutive information integrated into relational databases; this mainly concerns keywords allowing queries for the estab 
lishment of thematic maps 
• Descriptions, images and sketches in text format which can be monitored over special links whenever needed 
• Orthophoto as geometrically referenced raster images 
• Images of façades with geometric references 
• Geometric referenced video sequences 
The main concern went to the hierarchical organisation of the geometric information and to the linked attributive information. The 
main objects are shown in fig. 4. It is understood that all the elements are connected to attributive data, stored in a relational database. 
It would lead too far to explain the effectively used data catalogue in more detail here. 
Valley 
T 
Province 
T 
Municipality 
▼ 
Limitation of the ksar 
Special Constructions 
Fig. 4: Overview over the hierarchical organisation of the geometric information 
6.3 Choice of the Information System 
The preceding considerations made it evident that the CAD system MicroStation in connection with the information system MGE 
and facilities for the treatment of raster data will meet to a great extent the defined requirements. According to the various evalua 
tions, it seems that ArcView in connection with Arclnfo is - at least for the moment - not able to meet all the requirements, especially 
regarding 3D referencing. Without any doubt it would also be important to evaluate AutoCad. However, up to now it appeared that 
the possibilities for the connection with a database and the possibilities for the treatment of raster data are not really satisfactory. As 
far as is known, this problem seems to have been solved in the meantime. To a great extent, the choice was also influenced by the 
means available at the Institute of Photogrammetry and the relevant experiences. The CAD system MicroStation allows the use of 
special elements, yet it soon showed that it was important to allow the indexation of individual façades. 
MicroStation can be connected with MGE (Intergraph) or with Geographies (Bentley). Tests with Geographies had been of quite 
some interest and showed its potential; however it appeared that the necessary reliability is not yet achieved with version 2. For the 
final implementation we therefore preferred MGE. Within MGE there are modules available for the communication with Internet like 
GeoMedia and GeoWeb. 
6.4 Presentation of the Results 
The information system presented here in connection with MicroStation and MGE allows one to meet the requirements for the pres 
entation of the results. Over the information system MGE, one can generate various thematic maps with the help of special queries 
(cf. fig 2a). 
One particularity is the possibility of generating orthophotos that are coloured thematically (cf. fig. 6). Orthophotos are a very appro 
priate means in order to show a region as realistically as possible. It is very easy to combine orthophotos with line and point symbols. 
The use of area symbols is however very limited and heavily reduces the readability of the photographic content. One way out is the 
use of pseudo colours. That means that the content of the image is not presented in the colours of the photo but thematically variable 
colours, for example the ksour in various hues of brown, new constructions in violet and the vegetation in green. In this case the 
photographic content remains readable but it is very easy to recognise its thematic attribution.