There are tools to combine the most accurate data with 
the other ones, or to leave the two data types separately 
in the same system. This coordinate system allows also 
the integration of hybrid data types like raster data, 
images, facade plottings (Grussenmeyer, 1994, Figure 4) 
4.6. The hierarchical structure 
Finally, the hierarchical structure of complex objects is 
the following : (Figure 3.) 
3-D complex objects 
.. Blocks 
.... Primitives (Geometric or CAD) 
Rd Facets (basic elements : Edges / Contours / Nodes / 
Contour points) 
creme Faces (basic elements : Lines / Summits / 
Contour points) 
aa Bands (basic elements : Lines / H-Summits / 
H-Contour points) 
Aot Lines (basic elements : Lines / Summits) 
eft Traces (basic elements : Lines / H-Summits / 
H-Contour points) 
LH H-Points 
5. DATA ACQUISITION AND CONSTRUCTION TOOLS 
The data acquisition is performed by means of numeric 
information (coordinate). The adaptation and integration 
of the topology into the 3-D space takes place as soon as 
the metric data are measured. 
The modelling of the objects is based on the way of 
acquisition and updating. 
To build objects, it is necessary to have a range of 
specific tools : (Figure 2.) 
e different projection modes (horizontal, vertical, 
parallel to predefined directions) 
e different intersection modes (with the DTM, between 
objects, between surfaces) 
e extensions, parallel lines, closing of polygons, angular 
predefined polygon ways. 
e adjustment and integration of profuse data. 
As soon as the terrain measures are sufficient in number 
for the definition of the object, this one is formed and 
placed in the restituted space. All the measured points 
  
Figure 4. Architectural photogrammetry (Castle of 
Lichtenberg - France) 
are stored as ground information. The final object is a 
hierarchical agregation of blocks which are a 
combination of basic primitives. 
6. INTEGRATION OF TOPOLOGY AND ATTRIBUTE 
DATA 
Besides geometric representations, topology and 
attribute data are two other important components in 
GISs. A harmonic integration of these components is a 
vital issue in 3-D developments (Rongxing, 1994). 
The database is structured according to the modelling. 
The concepts of hierarchy and agregation are the basic 
concepts that define the relation between the complex 
objects and the primitive elements. The attribute data are 
structured from the same principles. 
CONCLUSION 
3-D urban objects can be classified into two categories : 
the regular and the irregular shaped objects. The 
irregular shaped objects can be modelled with DTM 
algorithms. The regular shaped objects are a 
combination of geometric primitives like the primitives of 
constructive solid geometry. But for preserving the 
geometric reliability it is necessary to supplement the 
structure of these primitives with a  hierarchic 
composition of basic elements. Local coordinate systems 
and transformation tools are other very useful 
components of such systems. 
References from Journals : 
Rongxing, L. Summer 1994, Data structures and 
application issues in 3-D geographic information 
systems, Geomatica vol. 48, N°3, pp. 209 to 224. 
References from Books : 
Bill, R.; Fritsch, D; 1991, Grundlagen der 
Geolnformationssysteme, Band 1 Hardware, Software 
und Daten, Karlsruhe, Wichmann. 
Kraus, K., 1994, Verfeinerte Methoden und 
Topographische Informationssysteme, Photogrammetrie 
Band 2., Dümmler Verlag, Bonn. 
References from other Literature : 
Grussenmeyer, P., 1994, La photogrammetrie pour 
l'étude et la sauvegarde des sites et des monuments 
historiques, Workshop on new Methods and Techniques 
for the preservation of Historic Sites and Monuments, 
Cairo. 
Kager, H.; Halmer, A.; Heitzinger, D.; 1996, Modelling of 
3D-Surfaces with Basic Topological Structures, Vienna, 
Presented paper Commission IV, IAPRS Vol. XXXI/A. 
Kraus, K., 1991, Die dritte Dimension in  Geo- 
Informationssysteme, Schriftenr. des Institutes für 
Photogrammetrie der Universität Stuttgart, Heft 15 pP. 
167-176. 
Neureither, M., 1992, Modellierung geometrisch- 
topologischer Daten zur Beschreibung und Berechnung 
netzartiger und fläschenhafter Strukturen, Dissertation, 
DGK, Heft nr 387. 
Pfeiffer, N.; Pottmann, H.; 1996, Surfaces Models on the 
Basis of Triangular Mesh-Surface Reconstruction, 
Vienna, Presented Paper Commission lil, IAPRS Vol. 
XXXI/3. 
464 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996 
  
  
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