DOCUMENTATION of HISTORICAL SITES by COMBINING MODERN
PHOTOGRAMMETRIC and LASER TECHNOLOGY
E. Vozikis * *, C. Boletis ^, J. Petrogonas ©
? IGD GROUP S.A, 6, Vyronos str., GR-152 31 Halandri, e.vozikis@igd.gr
" HELLENIC .MINISTRY OF CULTURE, 5, Metsovou str., GR-106 82 Athens, boletisk@otenet.gr
* GEOMET Ltd., 6, Vyronos str., GR-152 31 Halandri, j_petrogonas@geomet.gr
Commission V
KEY WORDS: Laser Technology, Cyrax 2500, 3-D model, Digital Photogrammetry, Point Cloud, Acquisition, Animation.
ABSTRACT:
The ancient theatre of Dionysus, in the southern slope of the acropolis rock, composes one of the most significant restoration
programs of the Ministry of Culture since 1984. The first theatrical installation in the site belongs to the first phase of the sanctuary
of Dionysus. The stone cave, dates from the end of the 4th C.B.C. along with the choragic monument of Thrasyllos at the uppermost
parts. Archaeological research has investigated important transformations during the late Hellenistic and the Roman eras in the
orchestra and the stage building.
Besides the monumental and environmental significance of this theatre the in site preservation of many architectural sections of the
cave permits, through restoration action, the implementation of a fuller image and the promotion of its intrinsic geometry. As
concerns the Thrasyllos monument its total restoration would offer a clear perception of a renowned choragic monument dating from
the glorious times of the occurrence of the ancient theatrical contests. By the middle of the 19th C. the theatre of Dionysus had been
buried for many centuries and only the Thrasyllos monument had been visible at the top of an area, which had been transformed to
something like a hill.
Because of the particularity of the project, the technical specifications could not be met by applying traditional means and methods.
After careful studying of the project needs, it was decided to use Laser-Total-Station for the measurement of the necessary
geodetically network and detail-points, metric and semi metric cameras with specially developed support device for the photographic
documentation, a precision Photogrammetric Scanner and a Digital Photogrammetric Workstation for the digitisation and the
processing of the images and a terrestrial Laser Scanning Device for the acquisition of the shape of the site surface.
This paper describes in detail the problems faced during the execution of all the phases of the project as well as the alternative ways
of facing them. Special reference has been given to the project planning and to the development of the necessary procedure for
engaging different types of data and production chains, in a practical and economic way.
Finally an analysis of the products and the achieved results was carried out, and the resulted figures concerning accuracy, time
needed and benefits are discussed in detail.
1. INTRODUCTION 2. METHODOLOGY AND RESULTS
This paper describes the survey and docomentation of the 2.1 General
theatre area, the inclusion of the previous architectural
documentation, the measurement of characteristic traces in the The stereoscopic image acquisition of the ancient theatre of
area and the production of a Digital Object Model. Dionysus was necessary for the needs of the future exploitation
of the theatre's material documentation.
Due to high model volume of information and the particularity
of this study, it was decided to use a combination of ^ These images should be metric in order to be exploited for the
photogrammetric and geodetic methodologies for the ^^ production of an orthophoto mosaic of the monument and for
documentation. The new technology of Laser Scanner, CYRAX the restitution of its characteristics. The coverage of the image
2500, was used for the production of the DTM. area includes the greater area of the theatre as well as the
; ; ‘ shuttles and the orchestra. All the photographs were taken
Aim of this work was beside the production of a final product, ^ during the time with the best photo-acquisition conditions in
the comparison of the results obtained by the use of CYRAX such a way to set off the plasticity of the surfaces, while not
with the corresponding results obtained by the use of preventing readability and distinctness.
photogrammetric techniques, in terms of accuracy, quality and
data management. Next, the methodology followed is presented A special camera (FUZIFILM GA645W1, FUJINON, f: 45mm,
step-by-step along with the technical problems faced and the format 5.5cm x 4.5cm) was used, calibrated for geometric and
corresponding results. radial distortions. The image scale was about 1:300, while the
images were acquired in 8 parallel flight strips, with 12 to 14
images obtained per flight strip vertical to the delineated level
* Corresponding author.
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