CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
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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-
