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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004 
  
as built between 1464 and 1478 as a part of a modernized 
fortification structure. In 1863 it escaped demolition with a 
majority of only one voice in a vote by the citizens of Lübeck 
(SCHADENDORF 1977). Today the Holstentor is a tourist 
attraction of the Hanseatic city Lübeck due to its national fame. 
The Holstentor was founded with its basic ground area of 
approx. 34m x of 12m and its height of approx. 39m on a bar 
rust construction, which rests on stakes in peat and marshy soil. 
The aim of the laser scanner recording at the Holstentor was the 
geometrically exact modelling of the building construction 
substance, which was already deformed during the construction 
phase. À detailed description of the project and the results are 
summarized in Jahn, 2003. 
  
  
  
Figure 1. Pipelines of the company Boie GmbH in Lübeck 
  
Figure 2. Western facade front of the Holstentor, Lübeck 
943 
3. THE 3D LASERSCANNING SYSTEM CYRAX 2500® 
The 3D laser scanning system Cyrax 2500 from Cyra, 
California, USA is one of the most precise terrestrial laser 
scanning system, which has become available on the market in 
recent years. Today the Cyrax 2500 is renamed to *HDS2500" 
as a part of the laser scanner series "High Definition Survey“ 
from Leica Geosystems. 
The system permits non-contact object recording at a scale of 
1:1 with a freely selectable point grid of up to 1.2mm. The 
scanning rate is 1000 points per second. The diversion of the 
laser beam is carried out over two rotatable mirrors in a 
measuring window of 40° x 40° (Camera View). By means of 
an optical system the focusing of the measuring beam is set to a 
diameter of 6mm at a distance of 50m. The 3D coordinate 
precision is £6mm at a measuring distance of 50m. In addition 
to the geometric information, an intensity value is stored as a 
fourth coordinate. Thus, the representation of the point cloud is 
color-coded on the basis of the intensity values (CYRA 2003a). 
The post processing of the data (3D point clouds) was 
performed with the modular software package Cyclone. The 
Cyclone software module model controls the scanning 
parameters during the data acquisition phase and allows the 
registration of the point clouds as well as the 2D- and 3D 
evaluation. With the COE (Cyra Object Exchange) data format, 
the loss-free data flow can be carried out to the CAD programs 
AutoCAD and MicroStation. Using the plug-in CloudWorx for 
both CAD programs the operator can work on the point clouds 
using the well-known user interfaces, while millions of points 
arc managed in the background by the Cyclone software. The 
basis for the use of Cyclone version 4.0.2 in the project 
processing phase was a three-day system and software training 
(CYRA 2003b) completed by one of the authors. 
4. RECORDING OF PIPELINES OF THE COMPANY 
BOIE IN LUBECK 
4.1 Data Acquisition 
Before scanning a local geodetic network was determined, 
which was supposed to be used for the subsequent geo- 
referencing of the different scans. Therefore, all geodetic 
measurements were conducted with the total station TCRA 
1105 plus from Leica Geosystems. After the final 3D network 
adjustment the data acquisition with the laser scanner was 
accomplished on two workdays. During the scanning phase 
Cyra targets (Fig. 3), which were well distributed in object 
space, were measured with the total station and determined in 
the local network coordinate system for the geo-referencing of 
the point clouds. 
The recording of the complete object by the laser scanning 
system (Fig. 4) required eight different scanner stations, which 
supplied 20 scans in total using a grid width of 1.5ecm. Thus, 
most pipings in the object space could be modeled in the 
evaluation phase, due to the available pipe diameters between 
4cm and 12cm. The measuring distance was between 20m and 
30m on average, therefore the precision potential of the laser 
scanner, which refers to a measuring distance of 50m, could be 
met. In total 11 million points were scanned, which yielded a 
file storage size of 257 MB.