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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004 
  
higher than other cases in the field of conventional cartography. 
Following these considerations we have justified a product 
which could present some metric characteristics out of 
standards: actually in difficult situations, as often it could 
happen in archaeological areas (e.g. Ancient territories of 
Mesopotamia, Medium East), the topographic operations for the 
survey of control points and the cartographic framework of 
reference have to be reduced as much as possible. 
The available updated cartography with a large scale is really 
rare: therefore we have the need to carry out the DEM, 
necessary for the ortho-projection, directly from topographic 
measurements (logistical problems) or through the stereo- 
restitution. In the latter case the inconvenient is due to the need 
to acquire the couples of satellite images. 
Considered that many settlements which are subject of our 
studies are luckily located in flat lands or in territories with 
slight levels’ variations, we often have used the most simple 
georeferencing models without using the differential 
rectification / DEM. In fact we have noted that the accuracy of 
the localisation of information on the images, related to the 
dimension of pixel, is compatible with the precision of these 
studies. (Fig. 3) 
  
Figure 3. Cartagine’s archaeological site (Tunisia): 
altimetric survey 
Information carried out from the satellite image’s study is 
verified, in cases considered relevant, by the archacologists 
directly on site. This check is made through GPS hand type 
(navigators’’) in which the option of differential correction is 
often absent. 
The precision of these instruments is well known and in the best 
cases the error of location on the ground overcomes the error of 
information location on the image simply geo-referred and not 
ortho-projected. 
It is understood that this consideration could be valid if the 
parameters of the applied transformation have been carried out 
on a solid basis, without errors and using a relevant number of 
control points. 
In a recent application we have tried what we have described 
before. We used a GPS receiver (Garmin) for localising the 
archacological data to be compared with information of a 
panchromatic/multi-spectral Ikonos image georeferred through 
15 control points (established through GPS observations with a 
Leica SR530 system-double frequency). 
The differences of levels noted in the working area doesn't 
overcome 30 meters and, considered the altitude of flight of the 
Ikonos satellite, a similar transformation applied to the 
panchromatic image has shown an average error of 0,68 meter 
(on the control points): the error is inferior to the pixel 
dimension. 
We have verified the error of localisation of information on the 
image by comparing the co-ordinates of some archaeological 
subjects with the topographic data acquired on site through the 
SR530 receiver in stop&go modality: the differences have 
normally been of 1-2 pixel, therefore maximum 1,60 meters. 
(table 1) 
  
  
  
  
  
Number of points mean 
Control points 12 0.68m+0.18m 
(GCP) 
Test points 9 0.82 m + 0.20 m 
  
  
Table 1. Control points, s.e.m. planimetric 
(survey Cartagine, November 2003) 
The data of the archaeological survey, with the GPS hand 
receiver, are obviously less precise and accurate: the 
localisation error has been generally bigger than 6-7 pixel. 
In the information system some maps have been integrated by 
digital treatment.. These maps, carried out with a 1:10.000 scale 
in some surveys in the ‘80s, are characterised by generic 
cartographic frameworks. The comparison with current 
topographic data has highlighted differences of 2-3 meters, in 
line with the attended planimetric error. 
Therefore, the basic data of the georeferred satellite data present 
acceptable metric characteristics if compared with the 
remaining available data. 
3. CONCLUSIONS 
In the survey's applications the metric contents have a relevant 
role, and this is well known to professionals, as we are, who 
have been working since many years on the development of the 
use of topographic and photogrammetric methods. 
However, we have also to take into consideration that the use of 
resources and tools have to be dimensioned according to the 
results we would like to achieve. 
In the specific area of archaeological research, aimed at 
studying the territory, we have analysed, for the 
georeferentation of the satellite image, the advantages of the 
approach that we have defined — maybe improperly - 
‘simplified’, if compared to the redefined techniques which 
foresee more complex mathematical models. 
This proposal has been made because it is not possible to think 
that we could extend the use of satellite images to neighbouring 
areas, as the one we have considered, which require for a proper 
use some complex procedures. 
If we wish that the satellite images, in particular the ones with a 
high definition, are more useful in the field of archaeological 
research we have to be aware that their use, availability need to 
be improved and simplified from their source. 
Actually we can not think that for using these images we have 
to utilise redefined operations of them, operations which 
actually require the use of complex programmes allowing 
different corrections. 
Furthermore the use of these programmes is only for qualified 
personnel and equipped centres. This process could be done 
only when it is required an appreciable use of the images’ data