The drawings – diagrams in the Ephorate’s archive, except for those related to the Octagon, were mostly ground plans of the complex at a scale of 1:200 without elevations or references to fixed points. There were no drawings of sections, views/faces, or ancient floors of individual building complexes.
Following these findings, the mapping of the archaeological site was deemed necessary:
1st: to create an accurate and permanent basis for the mapping not only of already-excavated buildings, but also of new evidence which may emerge from future excavations.
2nd: to draw the precise location of the various buildings at the archaeological site, and
3rd: to map the elevations of all the selected points.
HORIZONTAL ALIGHNMENT CONTROL NETWORK
Initially, a dependent relationship εξάρτηση was established with the horizontal and vertical network of the Municipality of Thessaloniki. For this purpose, twenty polygonal points were created at the archaeological site, while simultaneously four fixed polygonal points in the network of the Municipality were employed.
The points were resolved like a single mixed trigonometric network, and for greater precision έγιναν όλες οι μεταξύ τους παρατηρήσεις. Since many of the original points were abolished as work progressed, another 80 points were created.
ELEVATION CONTROL NETWORK
For determination of elevation, a dependent relationship εξάρτηση was created with two starting-points in the elevation network of the Municipality of Thessaloniki and with geometric levelling, an elevation was assigned to all the polygonal points.
MAPPING TECHNIQUE, FIELDWORK
In the final architectural drawings, both changes in linear elements in the various buildings as well as in the materials which formed their masonry and ancient floors (mosaic, marble, and others) are depicted. Towards this goal, the most appropriate method would have been photogrammetry. However, due to its significant cost, a different technique was followed which combined topographic, architectural, and photographic methods with good results.
This technique employed the following steps:
a. Determination of a horizontal plane and selection of the position of characteristic points
To draw the ground plan, a horizontal plane was selected for all the monuments in the complex. In this way, it was also possible to draw all the elements which appear below the level of this plane of intersection, including: upper surface of wall masonry, floors, conduits/pipes, etc.
The same plane was also employed for mapping the elevation of the points used for drawing sections and views of the monuments.
The points chosen in the field were points of change in direction of linear sections, openings, intersections, etc.
b. Marking the points
This was done with a distinctive color of enamel and numbered, self-adhesive marks στόχους which helped in the mapping and photographing of points.
c. Compilation of the rough sketches (Croquis)
Sketches are the most important and sensitive work done in the field, because they are the crucial element that not only allows the drawing, but also the discovery of mistakes that inevitably occur in the field. Sketches were made for each site separately and for each point mapped, noted with the code number which characterized each specific point until the conclusion of the work.
MAPPING THE POINTS
The instrument employed was a total station TOPCON GTS - 4 with an accuracy of angle measurements of 6 cc and a distance accuracy of 3+2 ppm. For the resolution of measurements, the topographic package GEOCALC was used. A total of 26,000 points were measured.
In parallel with the above work, the plotted points were photographed frontally with a camera and a 35mm architectural lens. In each photograph, the self-adhesive marks στόχοι with which the points were noted and the scale (which assisted their printing to scale) may be made out. At the same time, notes were kept on their classification.
The detailed photographic documentation of existing structures included:
- the photographing of constructions frontally, with successive overlapping zones.
- the printing of photographs at a scale of 1:25.
- the creation of a photographic archive with the classification and composition of the photographs to scale on A4 semi-hard cardboard.
Each shot included at least three of the plotted points, which are distinguished by the self-adhesive marks στόχοι with which they were noted. The numbers of the points included in each photograph were marked in accordance with the exposure and film number.
PROCESSING THE INFORMATION FROM THE FIELD - PREPARING THE DRAWINGS
The processing of the measurements included the automatic resolution of the plotting points on computer and drawing by a plotter.
Particular emphasis was given to the creation of a separate data archive for each building complex.
It was decided to use the following scales for the drawings:
a. 1:25 for each building complex (plan, view, section)
b. 1:100 and 1:200 for the entire complex
The final drawings were done using a combination of topographic points and scale photographs.