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LASERSCANNING AND PHOTOGRAMMETRY FOR THE MODELLING OF
THE STATUE MARC ANTON
Ch. Briese a ’ *, N. Pfeifer b , A. Haring a
a Institute of Photogrammetry and Remote Sensing, Vienna University of Technology, Gusshausstrasse 27-29,
A-1040 Vienna, Austria - (cb, aharing)@ipf.tuwien.ac.at
b Department of Geodesy, Delft University of Technology, Thijsseweg 11,
N-2629 JA Delft, The Netherlands - n.pfeifer@citg.tudelft.nl
KEY WORDS: Laser scanning, Close Range Photogrammetry, Heritage Conservation Research, Adjustment,
3D Modelling, Triangulation, CAD, NURBS
ABSTRACT:
Photogrammetry is a well-established method for the use of heritage recording and documentation, whereas terrestrial
laserscanning is a rather new technique for 3D object modelling. Both sensor systems have their individual advantages.
This paper describes the combined use of both techniques for the modelling of the statue Marc Anton. This statue,
located in the city center of Vienna, has an approximate size of 2.5m by 5m and has a height of 3m. The statue
represents Marc Anton sitting on a chariot pulled by three lions. The aim is to determine a 3D model of the whole
sculpture for documentation purposes (e.g.: showing differences in the used material, decomposition and offering the
possibility of adding further information to certain parts of the statue). First, we describe our experiences during data
capture and focus on a description of the acquired data sets. The following work can be split into two parts. The
first part deals with the registration of the different sensor positions and the orientation of the digital photos into one
statue co-ordinate system using hybrid adjustment techniques, whereas the second part concentrates on the 3D surface
modelling. The surface modelling is performed with the software package GeomagicStudio. After a 3D-triangulation the
surface is simplified using NURBS (Non-Uniform Rational B-Splines) in order to generate a CAD model. Finally, our
experiences with the combined use of both data capture methods ancl the modelling are presented.
1 INTRODUCTION
For a detailed heritage recording a lot of different
attributes have to be captured and stored to certain
parts of the object. For this aim a sufficient accurate
geometric representation of the object is necessary. For
the generation of such an object model different surveying
methods do exist. Depending on the necessary accuracy,
the complexity of the object and other limitations (e.g.
time for data acquisition) the most suitable measurement
system has to be selected. After the data capturing a
geometric representation of the object has to be defined on
the basis of the acquired data. This object representation
has to offer the possibility to decompose the object into
smaller parts in order to add local object attributes.
Photogrammetry offering - additionally to the possi
bility of accurate 3D point or line/curve measurements -
texture information, being very important for the purpose
of interpretation, is a widely used technique for 3D
object modelling. However, the measurement capabilities
are limited by the fact that point identification is only
possible in textured areas and that a high degree of
automatization can not be achieved on complex surfaces.
In contrast to photogrammetry laserscanning pro
vides a very high point density on the object surface,
within a more or less automatic recording procedure
([Pfeifer and Rottensteiner, 2001]). This allows a very
detailed surface description. Additionally laserscanning
is independent of texture information. In the moment
the disadvantages of this measurement method lie in
the measurement resolution and in the fact that laser
scanner systems do not provide high quality RGB-texture
information.
This paper deals with the combined use of both
methods in order to use the individual advantages of
"Corresponding author.
both mentioned measuring techniques for the recording
of the statue Marc Anton (see Fig. 1). The statue
located in the city center of Vienna has an approximate
size of 2.5m by 5m and has a height of 3m. The statue
represents Marc Anton sitting on a chariot pulled by
three lions. A fourth lion can be found on the back
side of the statue. The data capturing is described
in Sec. 2, whereas Sec. 3 describes the registration of
the different data sets, including also an accuracy analysis.
Challenging is the modelling of the detailed struc
tured surface (cf. Sec. 4). Details with extensions less
than 1cm can be found on the object, e.g. in the face of the
lions or Marc Anton. From the geometrical point of view
no parametrization over a plane or another simple surface
(e.g. a sphere or cylinder) of the whole statue is possible.
Furthermore, small holes (e.g. between the spokes of the
wheels) increase the complexity of the object. Due to the
overall complex structure occlusions cannot be avoided
and some areas cannot be digitized without tremendous
effort (e.g. underside of the lions bodies). To reduce the
time for data acquisition we accepted some data gaps and
some loss of detail. The following final section is devoted
to the discussion of the results.
2 DATA CAPTURING
For the data capturing we used the digital camera Ko
dak Professional DCS460c and the Riegl LMS-Z360 (cf.
K , 20031) laser scanner. The camera based on a Nikon
ses a CCD-array with 2036 x 3060 elements (6.2 mil
lion pixels) in the image plane with a pixel size of 9/xm.
50% of the pixels record the intensity of green radiation,
whereas 25% of the pixels are used to store the red and the
blue, resp. color information. With the help of an inter
polation method digital pictures with 2036 x 3060 pixels
are computed. To capture the object and the surrounding
tie points we used a 28mm lens with an average distance
