sity of Delft (van den Heuvel and Vosselman, 1997) 
makes use of a priori geometric object information in the 
form of parameterized object models with image lines as 
the main type of observations. 
This paper describes the performance and results of the 
three-dimensional reconstruction of the Disentis monas- 
tery from high resolution still video imagery with the soft- 
ware environment DIPAD (digital system for 
photogrammetry and architectural design). The object ori- 
ented measurements in DIPAD are guided by a topologic 
model of the object. In Sec. 2 an overview of the project is 
given. Sec. 3 describes the use of object models for the 
object oriented measurement approach within DIPAD, 
and in Sec. 4 the results of the processing for the monas- 
tery are presented. 
2. PROJECT DESCRIPTION 
2.1. Object 
The monastery of Disentis (see Fig. 1), located in the re- 
gion of Surselva in the Swiss Alps, is one of the oldest 
monasteries of Switzerland. 
  
Figure 1: Disentis Monastery 
(viewed from south and east) 
Its history reaches back into the 7 century, where the 
bishop Ursizin initiated a monastery in Disentis. After the 
reformation the monastery became a center for humanistic 
and natural sciences. During acts of war at the end of the 
18 century the monastery was destroyed and it took a 
century before it was rebuild. 
The actual building is a uniform complex which matches 
quite well with a rectangular ground plan. However, the 
structure of the building has changed many times during 
its long history. Parts of the building were added, de- 
stroyed, or after destructions rebuilt. In the 11 century a 
cloister and two centuries later the eastern tower and the 
western living rooms were added to the building. The 
south facade and the middle wing were finished in the ba- 
roque period and finally, at the beginning of the 18% cen- 
tury, the church with two towers was added. 
The approximate dimensions of the building are 120 m by 
60 m in plane and each of the two towers has a height of 
about 45 m. More detailed information about the monas- 
tery and its history can be found in (Schônbächler, 1992) 
and (Bürke, 1984). 
2.2. Camera 
The imagery for this project was acquired with a high res- 
olution still video camera. The main advantage of still 
video cameras is the fast and easy image acquisition with 
the feel of an SLR camera. These systems combine image 
acquisition, analog-digital conversion, storage device and 
power supply in one system, and offer the possibility to 
control the quality of the acquired images immediately on 
the spot and use them directly for further processing. 
The Kodak DCS 460 still video camera (Kodak, 1998) 
(see Fig. 2) with its high resolution CCD sensor 
(2036 x 3060 pixel) provides an internal slot for PCMCIA 
drives as image storage device with a capacity up to 54 
digital images. The camera features virtually all standard 
functions, including autofocus, automatic exposure, me- 
tering modes, flash and self-timing. 
The sensor unit is mounted on a slightly modified Nikon 
camera body. All standard Nikon lenses can be applied 
with the restriction of a slightly reduced viewing angle 
due to the smaller photosensitive area of the CCD chip 
(18.4 mm x 27.6 mm) compared to a standard film. 
  
Figure 2: Kodak DCS 460 
2.3. Image Acquisition 
During the project basically two types of images were ac- 
quired. One set of images was taken from a helicopter (see 
Fig. 3a) and another set of images was taken from terres- 
trial viewpoints (see Fig. 3b) 
Depending on the set of images different facts restricted 
the image acquisition. The restrictions for the terrestrial 
images were mainly given on the north and west side of 
the building due to occlusions and surrounding objects. In 
addition the situation allows only relatively short object 
distances. The image acquisition from the helicopter was 
restricted due to the minimum flying height permitted. In 
this case it was 50 m above ground. Thus the imagery was 
taken using two different lenses (28 mm and 18 mm), de- 
pending on the average object distances of the two image 
sets. 
  
Figure 3: Examples for acquired images 
(a) image from an aerial viewpoint with the 28 mm lens 
(b) from a terrestrial viewpoint with the 18 mm lens 
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