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EXPERIENCES WITH LASER SCANNING AT Bmainz 
Andreas MARBS 
i3mainz, Institute for Spatial Information and Surveying Technology, FH Mainz, University of Applied Sciences, 
Holzstrasse 36, 55116 Mainz, Germany, 
marbs@geoinform.fh-mainz.de 
KEY WORDS: Architecture, Cultural Heritage, Laser Scanning, Scanner, Software, Modelling 
ABSTRACT: 
Since a year and a half i3mainz uses scanners for cultural heritage recording tasks. Three different scanners were used: CYRAX 
2500 (time-of-flight laser), Mensi SOISIC (triangulation laser) and GOM ATOS II (structured light projection). These scanners are 
completely different regarding their principles of operation, specifications and typical applications. This paper will describe some 
projects, including problems experienced during scanning and postprocessing. Objects recorded include a cave, facades of a church 
ruin and a cenotaph. 
Just scanning an object is mostly the easiest part of the job. Creating exact models consisting of irregular surfaces requires a high 
expenditure of work and time. However, the various software products provided by the scanner producers are often optimised for 
industrial purposes and not for the creation of triangulated meshes, as necessary for objects in architecture, arts and archaeology. In 
order to be able to create both, geometrically accurate and good looking models, more intelligent software has to be developed. It is 
concluded that laser scanning is an important new method for the recording of cultural heritage objects, which can complement or in 
certain applications even replace currently existing methods. 
1. INTRODUCTION 
In the past years laser scanning or 3D scanning in general has 
become more and more important for the recording of regular 
(e.g. industry, piping) and irregular surfaces (e.g. sculptures, 
architecture, archaeology). The question arose: Can 3D 
scanning replace traditional photogrammetry or tacheometric 
measurements? This paper will give an overview about current 
projects at i3mainz, where scanning was used as a single 
method or for additional data capture. Problems which appeared 
during both, scanning and processing, are described and 
possible solutions are suggested. 
2. SCANNERS AT ttmainz 
i3mainz was in the position to be able to purchase two laser 
scanners, the long-range scanner CYRAX 2500 by Leica 
Geosystems and the mid-range scanner Mensi SOISIC LD. 
Furthermore, the short-range scanner GOM ATOS II was used 
by a sub-contractor at the cenotaph project in Innsbruck (see 
3.3). The following paragraphs will give a short introduction to 
each scanner with its principles and specifications. 
2.1 Mensi SOISIC LD (S25) 
The SOISIC LD scanner (it was renamed to ,,S25“ recently) is 
based on the plane triangulation principle combined with a 
cylindrical rotation. It is amenable to scanning both, smaller 
objects like statues, and larger objects such as archaeological 
sites, caves, rock walls, facades, plants, and so on. Since the 
SOISIC scanner has a relatively large base (as compared to 
other triangulation systems) of 0.8 m, it is possible to scan 
objects between 2 and 10 meters with better accuracy than other 
scanning products on the market. Due to the triangulation 
principle, the point accuracy decreases with the square of the 
object’s distance. The standard deviation is 0.4 mm at 2.5 
meters, 0.7 mm at 5 meters, 2.0 mm at 10 meters and 5.4 mm at 
20 meters. These values were determined by scanning a planar 
surface with the i3mainz Mensi scanner, fitting a plane to the 
point cloud and evaluating the standard deviation of a single 
point. 
An integrated stepping motor enables the scanner to rotate and 
capture a 320° field of view in the vertical direction. The 
scanning field in the base (horizontal) direction is derived from 
the camera’s field of view and is about 46°. The scanner is able 
to record approximately 100 points per second. To process the 
resulting cloud of points for creating models, Mensi provides 
the 3Dipsos software. Here the points are managed, edited and 
filtered. Special modules allow the creation of triangulated 
meshes and regular objects for engineering purposes, as well as 
the management of imagery and mapping of photo textures onto 
the model. 
2.2 Leica Geosystems (Cyra) CYRAX 2500 
The CYRAX 2500 scanner is a time-of-flight scanner which is 
applicable for larger objects with distances up to 100 meters 
from the scanner. Possible applications are the recording of 
architectural facades, plants or landscapes. Our scanner has a 
more or less constant accuracy of 2 to 3 mm between 1.5 and 50 
m range (determined with the method described above). The 
scanning speed is about 1000 points per second. Similar to 
Mensi’s 3Dipsos, Cyra offers the processing software Cyclone. 
It is mainly designed for the creation of CAD-Models out of 
raw point clouds. 
2.3 GOM ATOS II 
The ATOS II scanner by GOM is a digitising system that works 
with white structured light. The light pattern is projected on the 
object’s surface while two cameras record the reflected light. 
The scanner records 1280 x 1024 points in eight seconds. The 
scan volume may be anywhere between 0.6 dm 3 and 1.1 m\ The 
accuracy (noise) is from 0.002 up to 0.02 mm (for max. 
measuring volume). Typical applications for this scanner are