Documentation of Archaeological Sites and Monuments: Ancient Theatres in Jerash

________CIPA 2005 XX International Symposium, 26 September – 01 October, 2005, Torino, Italy________

DOCUMENTATION OF ARCHAEOLOGICAL SITES AND MONUMENTS: ANCIENT THEATRES IN JERASH
N. Haddad, T. Akasheh Dept. of Conservation Science, Queen Rania’s Institute of Tourism and Heritage, the Hashemite University, Zarqa 13115, Jordan, E-mail [e-mail], [e-mail]

KEY WORDS: documentation, immovable cultural heritage, 3D laser Scanner, Photomodeler, theatres of Jerash. ABSTRACT Modern technology has changed matters in documentation significantly and promises to continue to bring change. This paper attempts to present:1-How should we understand documentation of archaeological Sites, historic buildings and monuments according to their particularities, categories, types, components of documentation, taking into account the internationally agreed standards for the documentation of the cultural heritage. 2- The potential of the application of 3D laser Scanner and Photomodeler in documentation of the immovable cultural heritage. As a case study the ancient theatres of Jerash (the Southern and the Northern) will be presented. While the purpose of using different methods of documentation is to make comparison comparison of the advantages ,disadvantages ,the accuracy of the traditional method – total station –, 3D scanner method, and Photomodeler method. 1. INTRODUCTION As cultural heritage is a unique expression of human achievement, and since this cultural heritage is continuously at risk, documentation is one of the principal ways available to give meaning, understanding, definition and recognition of the values of the cultural heritage. As such it constitutes an important basis of orientation for subsequent restoration and maintenance measures. Furthermore all interventions acquire the character of evidence themselves and therefore, have to be documented. Article 16 of the Venice Charter emphasizes that in all works of preservation or excavation, there

References: Table 1 7. CONCLUDING REMARKS The documentation of the Jerash theatre was implemented by a combination of photogrammetry and 3D laser scanning. Generally:• Hand survey is labor intensive specially in the field. • Computer rectified photography is the simplest method of producing drawings. Metric cameras are no longer needed and can be substituted for with simple digital cameras. • The advantage of using photogrammetry is its speed and accuracy, especially over large and complex structures. • Cost will inevitably be one of the deciding factors in choosing between different recording methods, but should not be used to decide the level of survey. The effort needed to get accurate and detailed DEM models by means of photogrammetric procedures only, is considerably high. There are limits on precision based upon a different group of contributing factors, lens distortion, precision of lens focal length measurements, size of photos used. PhotoModeler is an elegant measurement method used in documentation of cultural heritage applications. The shortfalls of this method, mainly associated with limited geometry of areas in the shadow of the object, are more prominent when the object is a large complex form. However its use does not involve large costs or sophisticated equipment, as only a calibrated digital camera is needed. The recent emergence of terrestrial laser scanning has shown that it has the potential to be of major value to the cultural heritage recording professionals. While data collection in this project using the PhotoModeler and Laser scanning methods indicated a small gain in time over laser scanning, the main advantage is the fully automated data capturing process using terrestrial laser scanning. Generally, laser scanning requires viewing the surveyed object from several viewpoints to resolve shadows and occlusions. To achieve the best accuracy in PhotoModeler: 1. Ensure that a well-calibrated camera is used for the project, 2. Use photos with good resolution. 3. Ensure that the angle between the camera stations is as close John Coles,” The Site Record and Publication” Conservation on Archaeological Excavations, Ed.N.P. Sanley Price, ICCROM, pp.59-69, Rome, 1995 Photogrammetric Measurement, Object Modeling and Documentation in Architecture and Industry, Ed. Petros Patias, ISPRS, VOol.XXXII, Thessaloniki, 1999 Documenting the Cultural Heritage Edited by Robin Thornes and John Bold ,Getty Information Institute,1998 MENSI 2001: Mensi training materials, German training course, May 2001. WWW 2001: An extensive collection of links to laser scanner producers and reports about applications in cultural heritage is maintained by the authors at http://scanning.fh-mainz.de -www.international.icomos.org/recording_fre.htm Browning.Iain/ Jerash and the Decapolis/ Chatto Windus.London/ 1982/ (Ds154.9 G47 B76 1982). and Carl H.Kraeling/ Gerasa City of the Decapolis/ Yale University/ Published by the American Schools of Oriental Research/ New Haven, Connecticut/1938. W. Boehler, M. Bordas Vicent, A. Marbs ( Investigatgn Laser Scanner Accuracy , The XIXth CIPA Symposium at Antalya, TURKEY, 2003. Harrison Eiteljorg, How Should We Measure " an Ancient Structure?", Nexus Network Journal, vol. 4,no.4(Autumn2002),http://www.nexusjournal.com/Eiteljorg.ht ml) Boehler, W. , Heinz, G., Marbs, A. The Potential of NonContact Close Range Laser Scanners for Culture Heritage Recording,CIPA Working Group VI)2001.