M. Járó - L. Költő szerk.: Archaeometrical research in Hungary (Budapest, 1988)

Prospecting - ERDÉLYI Balázs, PATTANGYUS-Á. Miklós: Computer image processing and soil resistivity survey of an archaeological site discovered by aerial photography

ERDÉLYI Balázs*, PATTANTYUS-Á. Miklós** COMPUTER IMAGE PROCESSING AND SOIL RESISTIVITY SURVEY OF AN ARCHAEOLOGICAL SITE DISCOVERED BY AERIAL PHOTOGRAPHY Abstract -A rectangular object simaar in dimensions to a Roman Castrum was discovered on an aerial photo and investigated by geophysical methods. Computer image processing was carried out on the aerial photo. Geophysical anomalies were checked by shallow drillings prior to excavation. 1. Background During the interpretation of an aerial photograph taken for melioration purposes, a Roman camp was discovered on the outskirts of Turkeve (Erdélyi, 1981, Erdélyi, 1984), in the Great Hungarian Plain, very far from the Pannonian "limes", in the middle of Sarmatian land (Photo 1). Literature sources provide wide possibilities for determining the age of the fortress: from the age of Marcus Aurelius (the sixties of the 2nd century) to the time of the alliance after the wars during the era of Constantinus, i.e. to the mid-4th century (Erdélyi, 1984, Erdélyi, in press). The time of building can be defined and made more exact only by means of archaeological excavation. In 1983, an attempt was made to localize the camp under the direction of Sándor Soproni, but the excavations were unsuccessful. Since we could not achieve a greater accuracy using the original airphoto, application of digital image correction and mapping became necessary. This was realized in March 1985 at the laboratory of the Bayerisches Landesamt für Denkmalpflege in Munich, with the help of Helmut Becker, to whom we express our thanks hereby. 2. Digital image correction and mapping of the results The digital processing of aerial photographs and geophysical measurements was introduced to archaeology by Irwin Scollar in 1976, at the laboratory of the Rheinisches Landesmuseum, Bonn. The basis of the system is the complex equipment developed for handling satellite images (Scollar, 1977). Three computers simultaneously examine a photograph, handle the measuring results of the previous picture and, at the same time, apply the results of the last calculation series onto a film and map it. The resolution of the system is more than 16 times as great as that of a normal television screen (Scollar, 1978). The equipment of lower performance, by means of which we carried out the tests, was put into operation in Munich in 1983 (Becker, 1984). In the first stage, the picture (which may be a photograph, or a slide, or a negative, etc.) and the relevant sketch map were digitized by means of a video-camera and fed into the memory of the computer. The resolution of the video-camera is 262, 144 pixels * H-1116 Budapest, Latinka S. u. 13. * Eötvös Loránd Geophysical Institute of Hungary H-1440 Budapest, P.O.B. 35.