Proceedings 18 th International Symposium CIPA 2001 
Potsdam (Germany), September 18 - 21, 2001 
FROM 3D-LASER-SCANNING TO ELECTRONICALLY CONTROLLED REPRODUCTION 
OF SCULPTURES IN NATURAL STONE - 
A NEW SERVICE FOR A MORE EFFICIENT MONUMENT RESTORATION 
Thomas Kunze 
Kunze & Partner GmbH 
Technologiepark Friedrich-Ebert-Str. 
D-51429 Bergisch Gladbach 
Phone: +49-2204-842535 
Mobil: +49-171-3653870 
Fax: +49-2204-842536 
email: kunze@stone-tec.de 
URL: www.3D-Scanning.com 
KEY WORDS: Laser-Scanning, Reproduction of Sculptures, Natural Stone, Monument Restoration, Undercuts 
1. INTRODUCTION 
By using Laser-Triangulation Systems in the natural stone and monument restoration sector also complex figures with many 
undercuts can now be “scanned“. The German company Kunze & Partner GmbH being active in the stone and stone-technology 
sector for many years, is specialised in introducing new technologies that are not yet present in the sector so far. A particularly great 
interest could now be met with introducing 3-dimensional digitisation of objects, such as traceries, other architectural ornaments or 
even sculptures. This technology is in most cases referred to as “3D-Laser-Scanning”. The data revealed by Laser-Scanning can then 
be used for the reproduction of lost or damaged sculptures and ornaments. 
2. “3D”-SCANNING SYSTEMS ALREADY EXISTING IN THE STONE SECTOR 
The systems that have been already known in the stone sector for several years work in a way that the model that shall be scanned 
must be put into a milling machine. In the machine a so-called “3D-Laser-Scanner” is moved over the table of the machine (X-axes 
and y-axes) and the (in reality one-dimensional) laser will read out the depth of the model (z-axes). These systems are therefore 
limited to bas-reliefs that do not have any undercuts. Undercuts cannot be scanned this way. New versions of these traditional 
systems dispose of a linear guideway system that can be moved to the place where the original is located, in order that the original 
does not have to be removed from the site. 
3. NEW 3D-LASER-SCANNER SYSTEMS IN GENERAL 
In contrast to the above systems the new system presented here does not only measure the depth of a bas-relief put into a milling 
machine and is therefore not limited to bas-reliefs any more. 
An oscillating laser is scanning one perspective at a time, reading the geometry of the object not only as a single (Z-axis)-dimension 
in a sequential mode, but really in 3 dimensions by measuring the reflections of an oscillating laser. The digitising process as such 
taking less than 1 second, this gives an enormous advance in speed. 
After that the various perspectives can be aligned and merged together in special software packages. Examples for scanners may be 
the systems of Leica (CYRAX), Minolta (Vivid), the Callidus system etc. The output files will be ascii-point-clouds or polygon data 
that can be handled with various software packages. 
The following alignment of the perspectives from various view points on a CAD-computer makes it possible 
- to register form and figure from all sides, 
- to still register also special undercuts separately, 
- to incorporate especially important details in especially precise resolution, 
- to register also big objects of up to several meters width and height, 
- to easily scale the size of the object to whatever size is required. 
4. NEW APPLICATIONS IN RESTORATION 
The system is now applied to scan original sculptures or ornaments to reproduce them, or, if those are not existing any more, to scan 
some gypsum draft models that are often still existing in some museum archives, even when the original has been lost ore badly 
damaged. On the basis of the new 3D-Laser-Scanning systems described above Kunze & Partner do now integrate also the virtual re 
modelling of damaged or destroyed segments of figures of all kind, be it ornaments or sculptures.