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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B6. Istanbul 2004 
4. PHOTOGRAMMETRIC RESTITUTION THEME 
The semester theme of Photogrammetric Restitution will be 
exposed in more detail here for the simple reason that it was 
designed and is being given by the first author. The theme's 
main aim is to provide basic knowledge and training in the field 
of Photogrammetry. To this end, the theme contemplates a wide 
variety of techniques involved in the process of extracting 
geographic information from aerial photography, such that the 
student understands their relation within the process. 
The general learning objectives are twofold. The students are 
expected to learn how to extract geographic information from 
aerial photographs at a specific scale and for a specific purpose. 
The students are furthermore expected to acquire a good overall 
understanding of the various methods involved and of their 
relationships. 
The specific learning objectives can be grouped according to 
the 2 principal phases of the project. The first, Preparation 
Phase aims at "covering" the area to be surveyed with aerial 
photograph such as to permit the extraction of the required 
information with the required precision. This first phase thus 
involves, besides basic photogrammetric concepts, also 
concepts from Topography and Mathematics. The competencies 
that the students are expected to develop include to know how 
to do a flight planning, to plan the acquisition of additional 
information and the selection/signalisation of control points and 
carry out their measurement, to select the techniques and 
instruments needed to obtain the required end product(s), and to 
estimate costs and delivery time. 
The second phase of the project aims at the actual acquisition er 
the geographic information, using aerial photographs and i 
accordance with existing norms as well as user as 
This phase involves as key concepts the conversion of the 
topographic data to a specific coordinate system, and various 
advanced photogrammetric concept, such as aerial 
triangulation. The competencies expected from the students 
concern quality assessment of the basic input (i.e. the 
photography/images), preparation of the aerial photographs 
prior to information extraction (i.e. aerial triangulation), 
assessment of triangulation results, and actual extraction and 
representation of geographic information. 
The Photogrammetric Restitution theme is perhaps described 
best by means of a concrete case. In the current academic year 
2003/04, the task at hand was to create a data base for the 
production of topographic maps, at scale of 1:2.000, for an area 
of about 30 x 25 km? (Figure 2), together with precision 
estimates with respect to the extracted information. This area is 
characterised by hilly terrain (Figure 3), and consists largely of 
forest, urban and industrial areas. 
One of the main outputs of the first phase of this concrete 
project is the flight map. As one can easily imagine why, the 
flight planned by the students could not actually be executed, 
and instead, 20 aerial photographs of an existing flight were 
used in the subsequent phase of the project, arranged in sets of 5 
er flight line in a total of 4 lines. These photographs, with 
medium scale 1:8.000, covered just a small part of the above- 
mentioned survey area for reasons of time and logistic 
constraints (Figure 4). 
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Figure 2. Area to be mapped (approximate scale 1:356000) 
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Figure 3. Terrain morphology of the area to be mapped 
  
Figure 4. Aerial photographs used for restitution. The points 
used in the aerial triangulation process, including check points, 
are also seen in red.