CIPA 2003 XIX 11 ' International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
Density and accuracy have a very big range in the optical 
scanner; therefore it is a flexible system. It is quite obvious that 
improvements in accuracy and density are exponentially 
expensive in processing time, approaching laser scanner’s 
figures if decided to compete. Still there is a certain limit for the 
optical scanner in terms of density and accuracy, not to mention 
that in laser’s figures of density and accuracy the optical 
scanner cannot compete. From the very beginning though, this 
was not the task for the optical scanner. 
Laser scanner’s processing time is dig mainly because the total 
time for a single scan with the optical is much smaller, although 
additional processing is necessary. The CNC is moving slowly 
in order to achieve the requested density and therefore a single 
scan can take from 30 min up to 4 hours. On the other hand 
points gathered are many and there is no problem in 
discontinuous surfaces. If there are many discontinuities it will 
be necessary to rescan the same area with different focusing 
settings, hence exploding time. On the opposite side, the optical 
scanner cannot accommodate discontinuities due to conceptual 
design, no matter how much time will be dedicated in 
processing or photography. 
Undercuts are the basic problem of both systems, but the optical 
scanner is more sensitive because it is based on the assumption 
of surface continuity. Therefore only one uninterrupted surface 
can be modelled by using a single photograph. This fact poses 
limitations on surface complexity. 
Therefore, unless it is a very simple geometry, both methods 
need filling of small gaps. Therefore it is necessary in most 
cases to post process data by a specialist on 3d modelling 
(industrial designer in our case). The optical scanner is more 
sensitive in occlusions and steep slopes, hence limiting its use. 
CNC and laser scanner is out of the question due to limitations 
of the scanning area. Laser scanner on a mechanical arm might 
be the best solution for such objects, although double scanning 
of areas, which is unenviable, can cause serious problems. 
Portable laser scanners (in principle the laser head itself 
enlarged and modified for such purpose) are in author’s 
knowledge the best solution. 
In both cases the points gathered form a huge data set, difficult 
to handle by any system. NURD modelling (mathematical 
representation of the surface) although time consuming and 
mostly manual, produces much better results, provided one is 
determined to invest in time for correction and conversion in 
addition to the inevitable lose of accuracy. Result, though are 
far better for continuity of the surface on the reconstructed 
model. 
It must be noted that certain recent improvements in the optical 
scanner have raised its cost, but increased its functionality, 
hence increasing functionality, portability and decreasing a bit 
processing times and sensitivity to discontinuities. 
Further research includes expansion of the technique on smaller 
objects such as coins. 
References: 
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moving camera. IAPRS Vol XXXI, Part B5, Vienna 1996 , pp 
220-224. 
Kloudas, T., 1995. Three dimensional surface reconstruction 
with the Zeiss photogrammetric industrial measurement systme 
InduSurf digital. IASPRS, Vol XXX, Part 5WI, Workshop 
“From pixels to sequences’’, Zurich, March 22-24, 1995, pp 
285-291 
Luhmann, T., Wendt, K„ 2000. Recommendations for an 
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Pollefeys, M., Koch, R., Vergauwen, M., Van Gool, L„ 1999. 
An automatic method for acquiring 3d models from 
photographs: Applications to an archaeological site. ISPRS Vol 
XXII Part 5WII, Workshop “Photogrammetric measurement, 
object modeling and documentation in architecture and 
industry’’, Thessaloniki, Greece, 7-9 July, 1999., pp 76-80. 
Scaioni, M.. Vassena, G., Kludas, T., 1996. Automatic DEM 
generation using digital system InduSCAN: An application to 
the artworks of Milano Cathedral finalized to realize physical 
marble copies. IAPRS VolXXXI, Part B5, Vienna 1996, pp 581- 
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Greece, 7-9 July, 1999., pp 215-219. 
Yixuan, Z., Miaozhong, X., Chan. M., T., C., Zhihao, H.. 1999. 
Investigation on DSM generation for objects with complex 
surface by Photomodeler and Autocad. ISPRS Vol XXII Part 
5WII, Workshop “Photogrammetric measurement, object 
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Thessaloniki, Greece, 7-9 July, 1999., pp 252-257. 
Zhou, M., Fraser., C., S., 2000. Automated surface extraction in 
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5.1 Acknowledgements. 
Work reported, is part of the Eco_marble research project, 
financed under the Growth European programme. Participants 
were GeoAnalysis S.A. (Thessaloniki, Greece), Fraunhofer 
Institute (Bremen, Germany), Polyline S.A. (Thesaloniki, 
Greece), FitzWilliam Museum (Cambridge, U.K.), IT'P Gmbh 
(Bremen, Germany), Archaeological Receipt Fund (Athens, 
Greece), Materialise NV (Leuven. Belgium), Focke Museum 
(Bremen, Germany).