International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004 
  
Conclusions and outlooks 
From the analyses made, we can affırm that in the laser scanner 
sector, the products available on the market today are able 10 
fully meet the needs of metric survey in an architectonic and 
urban scope: depending on the models, every instrument can 
meet a more or less ample range of applications. 
In essence, the biggest problems are related to the lack of 
operational completeness of the various software that requires 
the user to use several software programmes. 
To date, processing the data acquired is not a mundane 
procedure: it must be conducted very carefully and every 
individual phase (from pre-processing to modelling to mapping) 
must be done with care, analysing and validating the results 
acquired, and while selecting the software to use very carefully. 
It is important to consider that the treatment phase of the data 
holds a predominant place in the economy of the work and it is 
important to choose not only the laser scanner model but also 
the software that can obtain results that meet the needs of 
precision normally associated with survey work. 
The Riegl laser scanner and the software used have made great 
steps forward in terms of obtaining these results: strict handling 
of the data, accuracy in the individual procedures, by obtaining 
graphics (vector and raster rectifications, 3D surfaces) finally 
comparable with the ones that can be obtained by following the 
more traditional survey methods, photogrammetry and 
topography (fig. 7 and fig. 8). 
  
fig 7 Comparison between restitution tiny and restitution from ortofoto 
with Scandig 3D 
  
fig. 8 Comparison between the two ortofoto: on the left ortofoto from 
photogrammetry and to right ortofoto from laser scanner 
One problem encountered is linked to the quality of the digital 
images. Even when carried out with a Nikon D100 with 6.1 
million pixel sensor and while using the 20 mm focal, the 
resolution of the image is insufficient (7 few pixels) and a 
resample has to be done from the ground up to generate the 
orthophoto at a scale of 1:50 (fig. 8 ). The solution lies naturally 
in the choice of lens to use. 
Digitalisation of the 3D orthophoto, made with Scandig3D, can 
be considered at the nominal scale of 1:50 and an average 
deviation of 2.5 em was found during comparison with the 
photogrammetric rectification. This deviation is mainly caused 
by the difficulty in recognizing the architectonic elements in 
photogrammetry and with laser scanners. The current state of 
conservation of the material of the Arena has made the object 
devoid of corners: from this, we find that the identification of 
the contours on the curved surface is influenced by. the 
interpretation of the person doing the rectification. In 
conclusion, the differences encountered were due to the 
different interpretations by the various professionals involved. 
Therefore, integration of the laser scanner, as an instrument for 
terrestrial survey, with the digital calibrated camera obtains not 
only vectorial and raster rectifications more conveniently, it also 
produces more sophisticated representations such as the 3D 
orthophoto or solid image. These latter represent the new 
products that can be used directly by the final user, as extremely 
useful instruments i the sector of architectonic property, in 
particular in projects aiming to understand, document, and 
conserve architectures. 
The system proposed has also shown to considerably reduce the 
times of acquisition during the campaign in addition to having 
simplified some phases of data rectification (digitalisation from 
a single image) minimizing the costs of the "specialised 
portion" of the survey (hiring a specialised technician). 
Introduction of the laser scanner and development of these new 
and absolutely innovative products lead us to imagine a new 
role for operators in the survey field. 
For instance, a specialized scanning service - elaboration of 
laser scanner data in order to achieve only solid images or 3D 
orthophotos while leaving the rectification not to the specialist 
rectification expert but to the specialist in restoration or 
structures or history etc. 
Organization of this service, which will be experimented on at 
the photogrammetry laboratory at CIRCE, whose final users are 
graduate students, must be studied while considering a division 
into phases carried out by operators with diverse, specific areas 
of expertise. A preliminary organizational proposition might be 
as follows: 
® campaign phases: 
(by specialists in topographical survey, photogrammetry, 
and laser scanner) 
O  topographical survey (framing or support grids); 
O laser scanning (from several stations); 
O photo acquisition; 
9 processing phases: 
(by specialists in laser scanner survey) 
O filtering laser data; 
O  decimation of data (according to the nominal 
scale of the survey); 
O Reporting, aligning, georeferencing, scannings; 
€ production of the printouts: 
(by specialists in topographical survey, photogrammetry, 
and laser scanner) 
o solid images; 
o 3D orthophotos; 
® rectification phase: 
(by specialists in restoration, structures, etc) 
o use of software for extraction of horizontal or 
vertical profiles; 
o interrogation of solid images or 3D orthophotos 
(coordinates, distances) to rectify the plans and 
prospects. 
   
Interi 
—— 
Refer 
Kraus 
Verlag 
Miglie 
3D, G 
Dequa 
precis 
2001, 
pp. | | 
Borna 
Auton 
Laser 
Wark: 
Greec 
Rinau 
media 
4% Co 
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Bitell 
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