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New perspectives to save cultural heritage
Altan, M. Orhan

CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
Distributed Information Virtual Database Geo-Multimedia Applications
Figure 2. ReGeo system (Frech & Koch, 2003)
There is an ongoing research project funded by the European
Union aiming at the development of a comprehensive online
tourist information system of the Thuringian Forest area,
based on a geo-multimedia database. The project ReGeo
("Multimedia Geo-Information for E-Communities in Rural
Areas with Eco-Tourism" - Freeh & Koch, 2003) offers
tourists essential and useful information about their holiday
region, but also supports local business and administrators
(Fig. 2).
The touristic infrastructure and sights can be explored by map-
guided quests as well as by alphanumeric thematic search. For
geographical visualization, 2D tourist maps, aerial images
together with vector data as well as 3D models and 3D
sceneries are provided. To generate a 3D model of Wartburg
Castle being a highlight of touristic interest in the Thuringian
Forest, photogrammetric data acquisition and 3D object
reconstruction have been carried out.
Examples of 3D modeling and visualizing architectural objects
can be found in the literature related to photogrammetry,
surveying as well as computer vision. The "photogrammetric
way" including a detailed and precise 3D object reconstruction
is explained, e.g., in Hanke & Oberschneider (2002), Daskalo-
poulos et al. (2003), whilst computer vision techniques are
emphasized, e.g., in Pollefeys et al. (2003), El-Hakim (2002).
The different approaches have their advantages and
limitations. This paper is intended to compare photo
grammetric and computer vision methods for camera
calibration and image orientation based on parts of the
Wartburg data set.
The Wartburg is built on the top of a rocky hill. The terrain
slopes steeply away on all four sides of the castle complex.
Access to the inner courtyards is possible solely via a small
drawbridge. The outer facades of the Wartburg could be
photographed from only few viewpoints. Images taken from an
ultra-light airplane had to be added to get a sufficient ray
intersection geometry for the photogrammetric point
determination. The inner courtyards were successfully
recorded from the two towers, some windows, and from the
ground. Three image acquisition devices were used: The Rollei
d30 metric 5 and Canon EOS D60 SLR cameras, and a Sony
DCR-TRV738E camcorder (cf. Tab. 1 for tech, specifications).
The 5 megapixel Rollei camera provides some features of a
metric camera, such as fixed focal length and a rigid
connection between lens and CCD chip inside the camera. In
addition, two focusing stops can be fixed electronically, i.e.,
the interior orientation parameters at these two focus settings
can be regarded as known over a period of time, if they were
once determined by camera calibration. The d30 metric 5 used
within the Wartburg project was calibrated for the focal length
f, = 15 mm and f 2 = 30 mm. The setting f 2 was used for the
images taken from the ultra-light airplane, whilst f ( was
employed for all other images. The Canon EOS D60 providing
a wide angle lens, 6 megapixel sensor and larger image size as
the Rollei camera was used to record several parts of the
courtyards which could be acquired only from a shorter
distance. The camcorder served in addition to collect some
overviews and short image sequences (movies) to be presented
in the tourist information system.
Rollei d30 metric 5
Canon EOS D60
Sony DCR-TRV738E
Number of pixels
2552 x 1920
3072 x 2048
720x 576
Sensor format
9 mm x 7 mm
22 mm x 15 mm
Lens (focal length)
10 mm - 30 mm
(= 40 mm - 120 mm
for 35 mm camera)
20 mm (SLR)
( = 32 mm for 35 mm
3.6 mm - 54 mm
( = 48 mm - 720 mm
für 35 mm camera)
Image data
6.4 MB uncompressed
raw data per image
7.4 MB uncompressed
raw data per image
0.8 MB
Table 1. Technical Specifications of the cameras used in the project