CI PA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
1. MAXIMILIAN I’s CENOTAPH
1.1 Historical background
Between 1420 and 1665 Innsbruck was the residence of one of
Europe’s most known imperial families, the “Habsburger”. The
Hofkirche at Innsbruck with the tomb of Emperor Maximilian I
probably is the most important art-historical monument, which
is possessed by the country of Tyrol. It was built between 1555
and 1565 under Emperor Ferdinand I (the brother of German
Emperor Karl V). It contains the most important German empe
ror grave of Maximilian I. The cenotaph (i.e. technical term for
an empty tomb) with the statue of the kneeling Emperor is in the
center of the church’s nave. The tomb was created by artists
from various countries, who cooperated in the production. It is a
unique certification of European court art, which was influenced
by the personality of the Emperor and its successor as clients.
The sarcophagus is surrounded by 28 more than life-sized
bronze figures, embodying ancestors and relatives of Maximi
lian, the so-called "Schwarze Mander" (i.e. black men).
1.2 Description
The cenotaph (fig. 1) comprises about 3 m x 5 m. The top of the
Emperor’s statue is 4,5 m above the base. The cenotaph consists
of a frame of black marble in which the 24 reliefs of white
marble (each approx. 82 cm x 55 cm) are embedded in two
horizontal rows. These reliefs show scenes from the life of the
Emperor Maximilian I. They have a level of detail within the
range of 0.1 mm and had to be documented in particular and
with highest available precision. On the cover of the tomb the
kneeling figure of the Emperor is central, surrounded by
representations of the four basic virtues, which are arranged at
the four corners. All mentioned figures consist of dark bronze.
1.3 Restoration measures 2000/2003
On the occasion of the preservation and restoration of the tomb
a complete art-historical and geometrical documentation was
initiated for the first time since the completion around the year
1568. In order to make a continuous access for tourists possible,
only in each case one half was concerned by the measures of
restoration and covered in a boarding. The other part remained
accessible for the public. However, the cenotaph was separated
for centuries by a wrought-iron lattice from the visitors (fig. 2).
Additionally the white reliefs were hidden by glass plates. In
May 2002 the right half was completely restored and it became
necessary to dismantle and transfer on the other side. Thus, for
ten days for the first time since its establishment the cenotaph
was accessible from all sides and unwrapped both from lattices
and from windowpanes (fig. 1). This time slot was used for the
complete documentation and the measurement work described
here.
2. DATA ACQUISITION
2.1 General remarks
The setting of tasks was not clearly defined - as is often the
case in comparable projects, and had to be developed in co
operation with the responsible authorities. It stood firmly that
the rare chance of accessibility from all sides should be used for
documentation by all means. Of course, neither detailed plans
nor art-historical documentations of this tomb were available at
this time. Because of the preciousness of the object - and the
uniqueness of the opportunity for data collection - accordingly a
combination of geodetic measuring methods was suggested and
carried out in May 2002.
Fig. 2: Total view of the cenotaph - behind lattices -
before the restoration work
On the one hand classical close range photogrammetry was used
for the complete measurement of the cenotaph and on the other
hand - due to the high detail of the reliefs - the 3D documen
tation should be carried out by use of 3D scanning techniques.
The geometrical survey of the object by the 3D scanners also
would be combinable in the future with the radiometric infor
mation from the photos when both methods were used in one
operation. The measurements were accomplished by three inde
pendent teams. In order to avoid interference during the short
time available, all measurements had to be coordinated exactly
and scheduled accurately in advance.
Since the surveying methods for the geometric documentation
of the cenotaph have been described in earlier publications
(Marbs 2002, Hanke 2003), only a brief outline is given in the
following sections.
2.2 Geodetic survey and photogrammetric densification
A general requirement for all surveys was a common coordinate
reference. A precise network of eight observation points around
the cenotaph was established and vertical and horizontal angles
were observed to the reference targets for the scans and the
photogrammetric images (spheres and self-adhesive flat tar
gets). An accuracy of better than 0.5 mm (standard deviation of
spatial location) could be achieved. Additional targets which
were necessary for the detail scans of the reliefs were stuck onto
transparent adhesive tape which was fixed in front of the reliefs
without touching them. The coordinates for those targets were
derived from photo triangulation using GOM’s widely automa
tic TRITOP system (GOM, 2003).
2.3 3D structural scanning with a MENSI S25
A complete scan of the cenotaph was achieved with a MENSI
S25 triangulation type laser scanner (MENSI, 2003). A point
density of about 2 mm was chosen. This resulted in 20
observation locations from where a total of about 10 million
points were recorded in about 60 hours of scanning time. As
long as a scanning range of 5 m is not exceeded, the MENSI
S25 will achieve a point accuracy of better than 1 mm.
