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International Archives of the Photogrammetry, Remote Sensing
and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
4. ECONOMIC BENEFITS
Use of a specification has several economic benefits.
Firstly, it ensures the client has a clear understanding of
the survey being delivered. It allows a measurable check
against the delivered data thereby ensuring best value. It
also minimises occasions when it is necessary to ask for
further work. Finally the delivery of appropriate
metadata allows quick and easy access to the available
data.
5. CONCLUSIONS AND FURTHER WORK
The process of defining a specification has allowed the
compilation of the significant issues relating to using
laser scanning for the survey of cultural heritage. It has
successfully produced a working document that can now
be further developed. It is necessary to continue to
consider how laser scanning may be used most
effectively for the survey of cultural heritage in general.
There is also a need to consolidate guidance on laser
scanning as a whole, for both airborne and terrestrial
systems.
Further work is required to define standard deliverables
relevant to cultural heritage subjects. These standard
deliverables should reflect the capabilities of the
machines on the desktop of archaeology and architecture
units. These may be 2D or 3D vector drawings, meshed
models using raking light to highlight particular features
or perhaps CAD models with annotations providing
condition assessment or aiding interpretation. It is also
necessary to outline the use of additional data sources to |
supplement laser scanning and to decide on suitable data
formats for the archiving of point clouds.
A further requirement is the definition of the minimum
standards for software and hardware to allow
archacologists to view data from laser scanning. The
education and training of archaeologists in ways to
manipulate this data to improve their interpretation of a
subject or site is also a necessity.
Throughout the project, including surveys undertaken at
Tynemouth Priory, Newcastle (Barber et al., 2003), it
was problematic to undertake effective data management.
This made production of metadata difficult and may lead
to resistance by commercial contractors to supply the
required information. Better data management systems,
including archiving systems, would benefit all areas that
utilise laser scanning in order to facilitate faster data
retrieval.
As detailed in IEC 60825 (2001) class 3B and class 4
lasers have been deemed unsuitable for use in survey
applications. Further work and investigation on the effect
of lasers of any class on living materials such as lichens
or on delicate paint work would be of particular interest.
The specification is now available for use by English
Heritage in defining project briefs and by contractors for
undertaking surveys by laser scanning. Most recently it
has been used by English Heritage in the tendering
process for a laser scanning survey of the Chester
Amphitheatre site, Cheshire. The addendum is, however,
expected to gradually evolve over the next few years to
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incorporate both the experience of use and increasing
technological advances.
6. REFERENCES
Barber, D. M., Mills, J. P. and Bryan, P. G., 2003.
Towards a standard specification for terrestrial laser
scanning. International Archives of Photogrammetry and
Remote Sensing, 34(5/C15): 619-624.
Beraldin, J.-A., Blais, F., Cournoyer, L., Rioux, M.
Bernier, F. and Harrison, N., 1998. Portable digital 3-D
imaging system for remote sites. Proceedings, IEEE
International Symposium on Circuits and System,
Monterey: 488—493.
Beraldin, J.-A., Picard, M., El-Hakim, S. F., Goudin, G.,
Latouche, C., Valzano, V. and Bandiera, A., 2002.
Exploring a Byzantine crypt through a high-resolution
texture mapped 3D model: combining range data and
photogrammetry. Proceedings, International Workshop
on Scanning for Cultural Heritage Recording, Corfu,
Greece. 160 pages: 65-70.
Bewley, R. H., 2003. Aerial survey for archaeology.
Photogrammetric Record, 18(104): 273-292.
Butler, L., 1997. Clifford' s Tower and the Castles of
York. English Heritage. 24 pages.
Bryan, P. G. and Blake, B., 2000. Metric survey
specification for English Heritage. English Heritage.
Swindon, 111 pages.
IEC, 2001. Safety of laser products — Part 1: Equipment
classification, requirements and users guide. Edition 1.2.
International Standard, IEC 60825-1.
7. ACKNOWLEDGEMENTS
The authors wish to thank the steering committee Clive
Boardman, Bill Blake, Tom Cromwell, Tony Davies,
Graham Hunter, Faraz Ravi and Tony Rodgers, in
addition to acknowledging the assistance of Leica
Geosystems, Z+F-UK and Riegl UK. The authors also
wish to thank the project sponsors, English Heritage
Archaeology Commissions Team (Project No. 3378).