Zastosowanie komputerowej analizy obrazów wizyjnych standardu VHS do badań przyczyn niszczenia budowli centrum ceremonialnego kultury Nasca : stanowisko Cahuachi, k/Nascua, Peru

• Authors: Skibiński Sławomir , Jagodziński Lech

Title variants

EN

THE APPLICATION OF COMPUTER ANALYSIS OF VHIS STANDARD VISION IMAGES FOR THE EXAMINATION OF THE DEVASTATION OF BUILDINGS BELONGING TO THE CEREMONIAL CENTRE OF THE NASCA CULTURE (THE CAHUACHI SITE, NEAR NASCA, PERU)

• Languages of publication: PL EN

Abstracts

EN

Magnificent buildings belonging to a ceremonial centre of the Paracas-Nasca culture have been discovered in the course of archeological work conducted as part of the „Nasca Project", near the town of Nasca in Peru. The existence of this culture is dated upon the base of archeological investigations at about 400 B.C. - 800 A.D. It developed originally along the Pacific coast in the Paracas Peninsula (the Paracas culture) and subsequently in the basin of the lea and Nasca rivers. The Nasca culture was characterized by a high level of crafts, which indicated connections with the Paracas culture and, during its decline, with the Tiahuanaco and Huari culture. Buildings which are part of the ceremonial centres of the Nasca culture, created in Cahuachi, near the modern town of Nasca, are covered with sand and gravel of alluvial and eolitic origin. This layer of sand protects against the destructive impact of atmospheric and civilizational factors. Following the removal of the sand by the archeologists, the rather well preserved edifices rapidly deteriorated. The purpose of investigations conducted on the site and in laboratories from 1987 to 1989 was to determine the causes of the rapid destruction of the buildings after their uncovering. The most important reasons were the considerable oscillations of temperature and relative humidity of the air, the erosion produced by wind and sunlight, and the ion exchange within the complex of the prime component of the building material. Another destructive factor was the impact of water circulating through capillaries. The presence of this particular factor would explain the poor protection of the walls' uppermost part as compared to the face. The former is most exposed to the sun rays and it is here, presumably, that the water evaporates. The intention of the investigation was to determine the probable range of the dampness of the wall of Templo Escalonado and its direction with the aid of a new method - a computer analysis of VHS signals. A high quality VHS Panasonic camera was used to obtain vision images, which were taped on a Maxell HGH casette. The vision signal was introduced into the computer's memory with a joystick of the image processor equipped with an IBM interface. The latter and the joystick make it possible to either transfer the vision image, sized 200 x 320 points from the camera into the computer memory, or directly from a video. The researchers employed a PC 3236 computer with a 16 kHz clock, and a super-VGA card and monitor, a 40 Mb hard disc and a Star Lc-10C printer. The interpretation of the vision images involved the use of a programme received from the producer of the joystick (IBM). This programme was adapted to an analysis of images for diagnostic purposes and to the configuration of computer equipment. The programme is now known as VIDEO v. 300. It can cooperate with a programme for the creation of stratigraphie documentation for mobile monuments (Ds-DOK C.200). In order to compare the picture on the monitor and the material produced by the printer, colour photographs of the pictures seen on the monitor were made. A standard Painbruch programme, in the 3.0 version (1985), prepared by SZOF, was employed for the purposes of the printer. A „Rzutnik" programme was proposed for receiving the obtained pictures in RGB, PCX and DAT sizes, which makes it possible to estimate the percentage of the contents of basic spectrum colours and the intensity of the produced computer pictures. Furthermore, it enables to calculate the percentage contents of sixteen hues of basic spectrum colours. Pictures of the object under examination were obtained by filming the surface of the wall vertically to the axis of the camera. This surface was also illuminated by sunlight and heated to a temperature of around 30-40°C. The filming was done in August 1987 at about 2 p.m. i.e. during the time when the wall reached its highest temperature. It was assumed that in damp parts the absorption of the rays will differ from the dry parts of the wall. Owing to the large impact of sunlight those parts which were slightly damp (for example, due to the condensation of the steam) were dried off prior to the examination. Therefore, the intensity of the red colour of the wall depended on water absorbed from the soil by means of capillaries. The great differentiation of the temperatures of the surfaces of the wall makes it feasible to propose interpretations despite the small precision of the VHS camera. The multi-spectrum analysis was conducted with the help of the VIDEO programme, using pictures transferred with AKAI equipment. These pictures were subsequently observed on a colour computer monitor steered by a super-VEGA card. After the selection of a suitable picture, observation were carried out of a full VIS spectrum (see diagram 4) and then successively only of the range of the range of the red (see diagram 5) and blue colour (see diagram 6). Undoubtedly, the interpretation of pictures obtained thanks to the multi-spectral analysis of VHS images remains extremely difficult at the present-day level of research. The pictures produced by this technique contain numerous information about the examined object. The ensuing task is to eliminate those which are inessential for the posed question and emphasize those which will facilitate the solution. The study in question presents first attempts at applying the computer analysis for data obtained with a standard VHS camera. This method made it possible to ascertain a possible presence of water circulating from the soil by means of capillaries in buildings belonging to the ceremonial centre of the Nasca culture in Cahuachi. This destructive factor was not taken into account earlier if only because the expanding loamy material made the walls watertight. Earlier research, however, proved the possibility of water being absorbed by the building material used in the objects of the centre. The above outlined investigations should be certainly continued and confirmed in other ways.

Keywords

PL

prace archeologiczne; archeologia; budowle Monticulo; badania w Peru; analiza obrazów wizyjnych; termowizja; fotografia

• Publisher: Narodowy Instytut Dziedzictwa
• Journal: Ochrona Zabytków
• Year: 1992
• Issue: 1-2
• Pages: 42-48

Dates

published

1992

Contributors

author

Skibiński Sławomir

author

Jagodziński Lech

References

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• J. Ru t k ows k i , Metody fotograficzne, W: Metody badawcze stosowane w identyfikacji i diagnostyce dzieł sztuki. „Zeszyty Naukowe ASP w Krakowie". Krakow 1980, nr 11, ss. 87-91.
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• A. S k i b i ń s k a , L. J a g o d z i ń s k i , S. S k i b i ń s k i , Komputerowy program dokumentacji stratygraficznej zabytkow ruchomych, „Ochrona Zabytkow" 1991, nr 4, ss. 290-295.

Identifiers

ISSN

0029-8247