TACHEOMETRY IN COMBINATION WITH BUILDING-ELEMENT ORIENTED 
CAAD-SYSTEMS 
THE INTEGRATION OF HIGH-PRECISION PLAN, SIMPLE 3D-MODEL AND 
SUPPLEMENTARY BUILDING INFORMATION IN A SINGLE SYSTEM 
D. Donath, U. Weferling 
Bauhaus-Universität Weimar, Chair Computer Science in Architecture 
donath@archit.uni-weimar.de, ulrich.weferling@archit.uni-weimar.de 
Working Group 6 
KEY WORDS: precise tacheometrie building surveying, 3D-model, information systems 
ABSTRACT: 
The use of CAAD systems for surveying historic buildings was previously not possible as such system models were not able to 
reproduce the uneven surfaces and deformations inherent in existing buildings. The use of modifiers applied to the standard CAAD- 
elements makes it possible for CAAD-systems to respond to the actual plan geometry of existing buildings. This is made possible by 
using CAAD-software in conjunction with tacheometrie software on a common working platform (for instance ADT Architectural 
Desktop). A 3D-model results directly from the survey and serves as a basis for visualisations, automated calculations (such as 
surface areas, volumes etc.) and as a 3D unit of reference for further non-geometric data. The practicability of the process was tested 
and exhibited using a real case study object. The main practical advantage of such an approach is the ability to quickly realise a 3D- 
visualisation of the surveyed building, in essence a by-product of the survey. This is useful for understanding relationships within 
the building and for initial planning studies. It is possible to link the model with further information but the results of this 
combination do not fulfil the requirements of a building information system both in terms of performance and usability. 
1. INTRODUCTION 
Building surveying and documentation in the field of building 
conservation and archaeology is characterised by traditional 
measurement techniques such as tape, measuring-stick, plumb- 
line and spirit-level. They have not been replaced by purely 
computer-aided measurement techniques such as tacheometry 
and photogrammetry. Instead computer-aided techniques are 
often combined with manual methods. However, even 
traditional surveying approaches must be oriented towards the 
requirements placed on the resulting survey by the future users. 
This is becoming increasingly time-consuming when 
undertaken using manual techniques: 
Very often geometric building surveys are required in 
traditional 2D representation as plan, section and elevation with 
a high degree of precision and detail. At the same time many 
wish to have a 3D representation though rarely at the same 
degree of precision and detail. In some cases it is also useful to 
combine non-geometric information such as photos or damages 
protocol etc. which relate to particular building elements and 
can be accessed through a room or object log. 
At present each of these requirements is typically addressed 
independently of one another: 
The plan and section is surveyed using a tacheometer to a 
high degree of detail and accuracy, 
A 3D-model is then created using the survey data 
Non-geometric information is then combined with 
geometric model using a database. 
All three requirements can however be integrated with one 
another using tacheometrie building surveying in conjunction 
with a building-element oriented CAAD-system. A pre 
requisite is that a CAAD-system can exchange information with 
tacheometrie software. At present a handful of CAAD-Systems 
- such as ADT Architectural Desktop (autodesk, 2003) or 
Palladio X (acadGraph, 2003) - and tacheometrie surveying 
systems - such as TachyCAD (kubit, 2003) or EITheo (pms, 
2003) - fulfil this requirement using the common work platform 
AutoCAD. Using such hardware and software, efficient 3D- 
models can be produced with high precision sectional geometry. 
2. HIGH-PRECISION TACHEOMETRY AND 
BUILDING-ELEMENT ORIENTED CAAD MODELS 
The process as described above can in part be achieved using 
currently available software products. Different software 
modules can be employed in combination with reference to a 
standardised working platform (ADT Architectural Desktop by 
AutoDesk). Both the CAAD-system Palladio X5 and the 
Tachymetry software TachyCAD are conceived as extensions 
to ADT and as such can be employed as tools in a platform for 
realising the planning-oriented capture of building information. 
Of particular relevance is the ability to use the tacheometer as a 
3D-mouse (fig. lb) to directly position Palladio X5 elements 
(fig la) within an overall coordinate system. 
Figure la. Definition of building elements in Palladio X5 
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