CIP A 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
2. PHOTOGRAMMETRY 
2.1 Data collection 
Digital Photogrammetry is a measurement technology that can 
be used for the extraction of 3D points from digital images. 
Thus, Photogrammetry derives all the appropriate 
measurements from the images, rather than measuring the 
object directly. That is why this technology provides significant 
advantages over the conventional surveying methods. Very 
often Photogrammetry is used in order to map and document 
cultural heritage objects like monuments, sites and artefacts. 
Starting from the requisite image orientations (interior, relative 
and exterior), Photogrammetry can provide automatic process 
through image matching techniques for the collection of 3D 
object points. Initially, a cloud of interest points is extracted 
from the images. For the acquisition of interest points, the key 
point detector Plessey-Grid (Stylianidis, 2003) was used. One 
step forward, using cross-correlation or least-squares matching 
techniques the extraction of the cloud of 3D points can be 
achieved. 
data so that they can be input into CAD software packages and 
of generating NC-programs for re-production in archaeology. 
Solutions for merging effectively independent laser scanner 
images into one common coordinate system will be presented. 
3.2 Procedures for Merging Images 
Several independent images must be merged when the object is 
larger than the field of view of the digitizer (camera) or the 
object exhibits undercuts. A very straightforward solution is 
using identical points in the overlapping area of neighboring 
images. This requires that these points appear with high 
contrast. In cases where identical points cannot be identified on 
the object itself, so called reference spheres can be applied 
(Wehr, 2001). Using these aids very precise results can be 
yielded. 
The Cartesian coordinates that are the result of the digitizing of 
freeform objects by the camera are transformed into object 
coordinates by special software postprocessor. The coordinates 
may now be processed as either NC-commands for copymilling 
(duplicating milling) or rapid prototyping machines or in the 
data format for the sculptured surface modeller. 
2.2 3D Model 
Single 3D points cannot provide a global illustration about the 
structure of the object. Thereby, the creation of the 3D object 
model is a requirement in order to depict the formation and the 
real conditions of the object. 
Furthermore, the 3D reconstruction is a requirement for further 
processes such as the application of visualization and graphics 
techniques which are explained in the following sections. In any 
case the 3D object model can be developed under standard or 
special CAD software. 
The case study that is presented concerns an ancient tomb, 
while in Fig. 1 the extracted 3D model of the tomb is illustrated. 
Figure 1. The 3D model of the tomb 
3. 3D RECONSTRUCTION 
3.1 Object Reconstruction in Three-Dimensions 
The presented example makes clear that one of the results of 
Photogrammetry is the generation of point clouds with a large 
amount of data which cannot be processed by standard CAD 
programs. This section addresses the problems of processing the 
3.3 Post processing of Object Coordinates for 
Reproduction 
A special software functionality is developed for the calculation 
and determination of loop contours out of one digitised dataset 
or out of the whole digitized object. In absence of a digitized 
statue this process is clearly seen in the example of the shop 
display mannequin (Figure 1 to Figure 5) and can be achieved 
in a two-fold process: 
First set the boundaries for the starting and the ending levels of 
the calculation. Secondly, the user has the choice to calculate 
the contours in iso-distance or according to the curvature (the 
first and second deviation) of the object. 
Figure 2. The calculated contours and freeform surfaces of a 
mannequin