C/PA 2003 XIX"' International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
Based on the very dense point clouds provided by laser 
scanners, the DSM can be derived directly from the laser 
scanner data (Wehr & Wiedemann 1999). If 3D vector data is 
available from tacheometry or photogrammetry it is usually 
necessary to derive a 3D boundary representation CAD-model 
as an intermediate product (Wiedemann 1996). This additional 
step is time consuming and may lead to additional errors. Based 
on these experiences a new strategy has been developed: That is 
to derive the DSM from intelligent tacheometrie measurements, 
which are to be acquired in an optimized manner. 
At the moment the software works with Leica total stations of 
the TRCM and TCRA types of the 1100 series. The program 
FAMES for the Façade Measurements uses the GEOCOM 
interface to control the total stations. 
Figure 3. Total station Leica TCRA 1103 
2. GENERATION OF DIGITAL ORTHOIMAGES 
2.1 Project Preparation 
The first step is the same for all serious documentation projects: 
The establishment of a site covering reference systems. For this 
purpose the system Archimedes3D provides a geodetic network 
adjustment. Signalized and natural control points are measured 
manually. 
2.2 Manual Measurements 
The next step is the generation of Digital Surface Models of the 
facades. For this purpose Archimedes3D controls the motorized 
total station. The process starts with the manual measurements 
at the facade, providing the system with the approximate extent 
of the object and lines and areas of special interest. The lines of 
special interest are vertical and horizontal profiles over the 
whole object or parts like cornices and window borders. Areas 
of special interest are reliefs or other decorative elements. 
2.3 Autonomous Measurements 
After this definition phase, the system starts to determine the 
exact extent of the object, to measure profiles and point rasters 
in different regions in a predefined density. 
The extents are located by stepping outward from the initial 
border points until the measured distance is significantly bigger 
than the initial distance or undefined. The last surface point is 
located using a suitable approximation procedure. 
The profiles are measured automatically in the predefined 
horizontal or vertical profile plane (Juretzko 2002). They are 
automatically densified by a process to locate discontinuities in 
the profiles. 
Due to the limited speed of the total station the acquired point 
density is much smaller than that of laser scanners but can be 
adapted to the actual requirements. The data rate is rather low 
with about 1-3 seconds per point. Therefore the operator must 
consider this data rate during the definition of the local raster 
density. 
Control Network Measurements 
Measurement of Inita! Parameters 
Autonomous Measurements 
Preliminary DSM Generation 
Additional Measurements 
Final DSM Generation 
Image Orientation 
Differential Rectification 
Figure 4. Data flow in Archimedes3D 
2.4 DSM Generation 
Starting with the overall profiles the data is used to produce a 
Digital Surface Model of the facade. Gaps and discrepancies in 
the DSM are located and closed by additional measurements. 
This process is automatic and requires no manual interaction. 
During this process, the operator can take pictures with the 
digital camera. A lot of points and features are geodetically 
measured. Therefore sufficient control information is available 
to do a “calibration on the job”. To achieve a better geometric 
stability it is recommended to restrain the quantity of interior 
orientation data by avoiding zoom and auto focus. Tools to