Photographic mapping of stone deterioration

Yiorgos Marakis <yomaros [at] yahoo__com> writes

>I am looking for information on the use of Photography for mapping
>the deterioration of stone.

We have developed a method for mapping the distribution of decay and
soiling on building facades. While it involves photographing the
facades, it was not possible to derive accurate information on the
distribution of decay from the photographs alone since the
resolution was not sufficient to be able to determine with
confidence the decay types or their intensity. We found the only
effective method to be surveying in the field. The facades were
initially photographed and rectified images produced. A3 or A4
printouts of these images were used in the field for recording the
distribution of soiling and decay types. These field mappings were
transferred to computer (using Adobe Photoshop 4) to produce separate
layers of information on the distribution of different decay or
soiling types that can be superimposed on the digital image of the
facade. By excluding areas that are not stone it is then possible to
calculate the surface area affected by particular types of soiling
or decay.

Our methodology and some results have been recently published. See
J. Ball & M.E. Young "A simple technique for rapid field assessment
of stone decay on buildings" and M.E. Young, J. Ball & R.A. Laing
"Quantification of the long-term effects of stonecleaning on decay
of building sandstones", both published in the proceedings of the
9th International Congress on Deterioration and Conservation of
Stone, Venice, 19-24 June 2000.

A very detailed methodology for mapping stone decay has been
developed by Bernd Fitzner and Kurt Heinrichs. This also uses field
surveys rather than working from photographs. See K. Heinrichs and
B. Fitzner "Deterioration of rock monuments in Petra/Jordan" in the
same proceedings and B. Fitzner, K. Heinrichs and R. Kownatzki,
1995. Weathering forms--classification and mapping. Denkmalpflege
und Naturwissenschaft, Natursteinkonservierung I, Berlin, 41-88.

Dr. Maureen E. Young
Masonry Conservation Research Group
School of Construction, Property & Surveying
The Robert Gordon University
Garthdee Road
Aberdeen AB10 7QB UK
+44 1224 263710
Fax: +44 1224 263777


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                  Conservation DistList Instance 14:20
                Distributed: Monday, September 25, 2000
                       Message Id: cdl-14-20-002
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