The Potential of Non-contact Close Range Laser Scanners for Cultural Heritage Recording 
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Figure 1: Time-of-flight 
Figure 2: Triangulation 
1.2 Processing of Results 
Scanning results in a cloud of isolated 3D points. Although the measuring process is very fast and simple, users should be well aware 
that, in addition to an appropriate software, time and patience are needed to arrive at a final result in the form of a CAD drawing or a 
surface representation with a triangulated mesh. Processing procedures should include recognition and elimination of wrong or 
inaccurate points. Since most objects have to be recorded from several viewpoints, methods to combine the separate point clouds 
have to be incorporated. 
If a CAD representation is desired, the software must be able to fit primitives (i.e. planes, cylinders and spheres) to selected parts of 
the point cloud. In the case of an irregular surface, tools are needed to create a triangular mesh. In either case, it may be necessary to 
map textures onto the created surfaces in order to achieve a photo-realistic appearance. The necessary digital images may derive from 
CCD cameras that are part of the scanning device or from external imaging systems. 
1.3 Overview of available scanners 
In the past few years many 3D scanners aimed at a variety of users and applications appeared on the market. The majority was 
produced for scanning, surveying and modelling of small objects of sizes ranging from coins to cars. The set-up for scanning of 
human bodies or body parts quite naturally allows also for the scanning of (about life-sized) sculptures or statues. As a result, these 
instruments are useful for some cultural heritage purposes although the producers constructed them just for applications in medicine 
or the clothing industry. The underlying principle of triangulation guarantees both high accuracy at distances below two meters and 
suitably fine grid resolution for small and detailed objects. 
The number of scanners that are available for larger objects or scenes is much smaller. Due to the poor accuracy of triangulation 
scanners at large distances, most of them work by “time-of-flight”. Naturally it is not sensible to scan distant objects with a grid 
resolution much smaller than the diameter of the laser spot on the object surface. Although some manufacturers equip their scanners 
with a laser auto-focus, the spot size grows with increasing distance. This explains why detailed scanning from large distances is not 
sensible. 
2. SOISIC SCANNER BY MENSI 
2.1 Specifications 
The SOISIC scanner, recently purchased by i3mainz, is based on the plane triangulation principle combined with a cylindrical 
rotation (Fig. 3). The French producer, Mensi, offers two different versions: SD has a base (distance from laser mirror to camera 
lens) of 0.5 m for distances between 0.8 and 10 m, and LD has a base of 0.8 m for distances between 2.5 and 25 m. 
The scanner bought by i3mainz is the long distance version. It was chosen because it is amenable to scanning both, smaller objects 
like statues, and larger objects such as archaeological sites, caves, rock walls, facades, and so on. The SOISIC scanner fills the gap 
between close and mid range scanners (cf. table 1). Due to its relatively large base (as compared to other triangulation systems), it is 
possible to scan objects at 10 meters and more with good accuracy. 
The basic components of the system are the SOISIC scanner itself, a tripod (1 to 1.8 m), a remote control PC with 30 m of cables, a 
calibration bar and ten spheres for registration. It is possible to mount the scanner on the provided tripod both horizontally and 
vertically. If there is little space at the scanning site, it can be put on the ground (horizontally). 
The SOISIC scanner is a cylindrical instrument with two openings, one for the laser diode and the other for the CCD camera. An 
additional video camera is installed next to the CCD. It is used to control the scanner by the PC. Furthermore, it is possible to use the 
video imagery for texture mapping on the processed 3D model. 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°.