The reason for the typical appearance of a stereoscopic 
impression, while viewing two corresponding stereo mates, is 
due to the 3dimensional human viewing sense ability. 
An attempt for a systematic investigation of the spectrum of the 
methods for virtual stereo presentation and stereo viewing has 
been carried out, resulting into 
* methods for the Spatial presentation of stereo mates projected 
without contact, 
* methods for the separation of Spatial presented stereo mates 
projected in contact and 
* methods using virtual 3 D models 
Not sufficient suited for appropriate virtually stereo 
representation and therefore not part of this investigation are, 
e.g., 
methods using simple central perspective effects and/or 
shadow effects, 
"2.5 D effects" if a queue of central perspective 
projections is just viewed without suited glasses, 
"continuous profiling" techniques, which are methods for 
3D data determination by combining a successive queue of 
profiles, but are not counted as originally own methods for 
virtually 3D data presentation, similar holds for 
the Moiré effect, while 
materialized 3D appearance, including 
the 3D window and/or mirror effect and 
reality (models) 
are no methods for virtually but for real 3dimensional data 
presentation. 
Suited aids for virtually stereo representation of 3D Laser 
Scanner data, namely to be used on a PC and subject for further 
research are in particular 
a) Methods for virtual Spatial perception of stereo mates 
projected without contact, e.g., 2 or more stereo mates 
vertically or horizontally arranged, in particular the stereo mate 
presentation for autostereoscopic visualization, mainly for 
normal and cross stereo mates, as well as verified for 
"Magic Eyes" and/or random dots test stereograms. 
Cyberspace supposed also to be mentioned, because here 
namely 2 "horizontally arranged" stereo mates, separately 
projected into the eyes, gain a Spatial perception. 
Other methods for the Spatial presentation of stereo mates 
projected without contact are the 
• lens stereoscopes: They are typically in use for viewing 
small format stereo-imagery and even stimulate the public 
interest in our profession. Stereo photos are very good 
suited, to simulate the potential of a sophisticated 
3 dimensional Laser Scanner data documentation, as a very 
important basic step for a good Spatial MIS data 
documentation. 
• In particular some million historic stereo pairs beside their 
documentary value, with important Geometric and 
Radiometric information, wait for digitization and for 
modem Spatial representation for restoration and 
comparison purposes etc., see Figure 4. As an example the 
authors successfully under http://stereoview.forU.de 
maintain "Dr. Schuhr's Stereo-Image Agency" with world 
wide samples and access on a non-commercial base. 
Figure 4. Sample for a currently international famous natural/cultural stereo mate: The "little" Buddha statue (of approx. 40 m 
height) in Bamian (Afghanistan) before destroying as shown on a Keystone stereoview (left) and after destroying by the 
Taliban Regime, waiting for reconstruction. 
Methods for the Spatial presentation of stereo mates projected 
without contact are in addition 
• the mirror stereoscopes, 
• prism stereoscopes for horizontal image arrangement, 
• wedge prism stereoscopes (KMQ) for vertical strip-image 
arrangement and 
• mirror stereoscopes without lenses, also known as Pigeon 
method. For the latter on a plane the left image is arranged 
beside its right mirrored stereo mate. While the left image 
is viewed directly with the left eye, the right image is not 
viewed directly but to percept from a preferably surface 
reflecting mirror to be used to separate both images. This 
principal is suited for screen representation as well as for 
room projections, if the attendees use a mirror. 
• Lenticular lenses, as typically known from 3D postcards, 
but also verified for Spatial PC data presentation, with and 
without head tracking, in true color are also mentioned 
here, because this method can be understood as a queue of 
stereoscopes (the lenticular lenses) is used for 3D viewing 
onto the 3D stereo mates (the alternating queue of 
corresponding, separately projected vertical strips of the 
stereo mates). 
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