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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B6. Istanbul 2004 
plotting, because would allow to locate with more ease objects 
featuring a contrasting colour, such as roofs, trees, green area, 
water surfaces. A realistic possibility would be to use HRSI 
pan-sharpened images. Pan-sharpened images are generated by 
merging the colour information contained in the lower 
resolution visible (or visible/infrared) multispectral bands with 
the geometrical information contained in the higher resolution 
panchromatic band. The result of the processing is a natural (or 
false color) pan-sharpened image, with the resolution of the 
panchromatic spectral band. 
It should be noticed that reported vector data directly come 
from interpretation of the image and have not been edited. In an 
operational production process, also this stage would be carried 
out, involving recovering of orthogonality, parallelism an the 
like. 
In the test area, other two cartographic product were available, 
i.e. a colour orthophotomap at 10,000 scale and a portion of the 
regional raster map (CTR) at the same scale. Because these 
maps are geocoded into the Italian official cartographic system 
(Datum “Roma40” based on the Hayford ellipsoid) using a 
modified Gauss projection (termed as “Gauss-Boaga”), a 
transformation to UTM-WGS84 system used for the IKONOS 
orthoimage has been computed. Due to the limitation of the 
area, a 2D conformal transformation would result enough 
accurate. 
Vector layers extracted from IKONOS orthoimage have been 
overlayed to both orthophotomap (Figure 6) and raster map 
(Figure 7). As can be easily understood, roads have been 
extracted with a high accuracy, completely conformal to 
tollerances adopted for 1:10,000 maps. In Italy, we usually 
adopt a cartographic planimetric tolerance which is twofold the 
size of the map resolution; in case of 1:10,000 maps, this 
tolerance adds up to 4 m. 
Of high accuracy and completness is the drawing of building as 
well, in particular when compared to the orthophoto. 
Comparison with respect to raster map shows several 
differences in geometric positions of buildings, but this fact is 
probably not due to the quality of the IKONOS orthoimage. 
Figure 4 — Patch of the orthoimage derived from an IKONOS 
over tha area of Lecco used in the test for evaluting the 
possibility for information capture from HRSI. 
  
Figure 5 — Overlapping of the extracted vector layers to the 
IKONOS orthoimage patch. 
  
Figure 6 — Orthophotomap (1:10,000 scale) derived from aerial 
photogrammetry with superimposed vector layers extracted 
from IKONOS orthoimage. 
  
Figure 7 — Raster regional map (CTR at 1:10,000 scale) with 
superimposed vector layers extracted from IKONOS 
orthoimage.