lann, Schwermann 
Photogrammetric 3D-Documentation of the Cathedral of Aachen 
143 
lints on the building 
asier and the image 
iable recognition in 
photographs or little 
ip additional 4 days, 
djustment tasks. Be- 
lordinate system. As 
1. Regarding that al 
ible. 
omplexity of the ob- 
the daily work. Sin- 
iges and the amount 
on the concrete sub- 
ed as a prerequisite, 
ig the image coordi- 
r the program deter- 
nal values of the ori- 
ive conclusions with 
■ bundle adjustment 
s accepted neverthe- 
orking days per sub- 
nsmitting of images 
in PHIDIAS is quite 
î orientation process 
ill 
gives an impression 
design elements are 
edimensional coordi- 
me the CAD-model, 
to the integration of 
itely usable. This is a 
l hand in hand. Thus, 
ng tools. This means, 
vertical or horizontal 
ntly continued during 
the surveying period of the cathedral. As an example, in the last tew years a new feature for stereoscopic measurement has been im 
plemented. Thus, two suitable images are very quickly and alternating displayed on the screen. In combination with special shutter 
glasses the operator gets a threedimensional view of the object and is now able to perform typical stereo measurements. Particularly 
difficult object surfaces with no distinct structure are now evaluable by this way. 
Figure 3: The digital photogrammetric evaluation system PHIDIAS together with MicroStation 
In all, the surveying of the external surface of the cathedral took up to nearly 4 years, within 1,5 persons dealing with the project on 
average. Figure 4 shows some results as wire frame designs. The drawings consist of different single designs, which are - following 
the partitioning into subprojects - independently stored in their own files. Merging of the single drawings is quite simple due to the 
reference techniques provided by the CAD-system MicroStation. Because of embedding all projects into the same unique coordinate 
system defined by the control points, merging is immediately feasible. 
4. SURVEYING OF THE INTERIOR CATHEDRAL 
At the beginning of the year 1997 the photogrammetric measurement of the interior part began. The cathedral of Aachen is a world- 
famous monument and for this reason met by many visitors every day. The measurement work with respect to the inside of the ca 
thedral had to consider this fact. Therefore the photographs were gradually recorded. Often only a few hours were availabe for taking 
the photographs and for measuring the control points, what happened parallel to the recording of the exposures. A tachymeter station 
measuring reflectorless with infrared laser was predominatly used to determine the control points. The amount of natural control 
points was completed by some artificial targets. All images were taken from the ground or the first and second floor, respectively. 
Similarly to the surveying of the external area the measurement of the inside has been partitioned into subprojects. The central octa 
gon and four of five attached chapels are consisting of two floors in each case. Therefore the partitioning with respect to theses cir 
cumstances was obvious.