CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
438 
Figure 3. Documentation-system 'freak' with its components 
server, taxonomy, sketch-tool, tacheometry, 2d-model, 3d- 
model 
The individual tools provide a continuous, evolutionary, 
flexible and dynamically variable system which address aspects 
ranging from the initial site visit to the preparation of 
professional detailed planning documentation. The tools are 
applied to a central model organised in a model management 
system. 
3.1 Phases of the surveying process 
1. Initial site visit: Recording of essential elements in sketch 
form 
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Figure 5. Information allocation using a tree-structure 
taxonomy 
2. Measurement: a survey of space-defining elements using a 
combination of different surveying technologies. 
Further tacheometric or photogrammetric measurements can be 
used to enrich and extend the basic geometric data with detailed 
measurements. Complex spatial arrangements and surfaces with 
different forms can be described in detail and in relation to one 
another. The basic information from the sketch-model is 
replaced with more exact tacheometric data as and when it is 
surveyed. 
The essential structure of the building is sketched out during the 
initial site visit. A touch-pad with pen is used together with the 
sketch tool from freak (Figure 4a). 
a) sketch with b) sketch-tool with c) adjusted model 
touch-pad distance measurements 
3. Architectural Model: the creation of specific building 
elements defined by the surveyed surfaces. 
The initial survey and later detailed measurements create simple 
objects such as surfaces, walls and rooms. These initial 
definitions need to be further detailed according to the 
requirements of the user (architect, archaeologist, 
conservator...). In a first step the results are used to establish a 
general architectural model. 
3.2 Adjustment computation 
The combination of manual and semi-automatic surveying 
techniques such as tacheometry and photogrammetry is a 
central aspect of the concept (fig.6). In addition, a surveying 
system should not predetermine the process of surveying. 
Figure 4. Sketching, surveying and adjustment of the geometric 
data model 
The sketch-model can be dimensioned using a series of key 
distance measurements (Fig. 4b). After computational 
adjustment this results in a correct geometric model that can be 
viewed in 2D-mode (Fig. 4c) or as a 3D-model with standard 
room height (see Fig. 3). This process is currently limited to 
straight wall surfaces and works best where walls are mostly 
arranged at right-angles and parallel to one another. As each 
building element and room is measured it is automatically 
added to the tree-structure of the taxonomy. In this way an 
object-oriented data structure can be developed from the first 
site visit onwards (Fig. 5). 
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a) not adjusted b) adjusted 
Figure 6. Integrated adjustment of hand-based measurements 
(yellow) in combination with tacheometry (green), 
photogrammetry (red) and geometric constraints 
The concept employs adjustment methods used conventionally 
in geodesy as a method of connecting measurements with user- 
configured geometric definitions and constraints. An initial 
approach links measurements to geometric form using point co-