The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008 
The percentage of entities belonging to each group is reported, 
as example, in table 2. According to this percentage, it was 
possible to classify this level in: 
• Metrically plotted, if at least 95% of the cases belong 
to Group A (P); 
• Visible, if only 60% of the case belong to Group A 
and 35% to Group B (V); 
• Not visible (NV). 
A map scale was chosen if all the levels were in the P category. 
This final subdivision is shown in the last column in table 2. 
These procedure were repeated, for each available flight, and, in 
each case a map scale was chosen. 
2.1 ADS40 1 st Generation 
The available images were taken by this sensor at an altitude of 
6000 m, with a GSD of about 62 cm. In spite of this, the quality 
of images is good, especially coloured ones. Two different 
areas were acquired with the same GSD: one over the city of 
Turin (Italy) and the other over the Susa Valley, the location of 
the 2006 Winter Olympic Games. 
Figure 2. An Example of the map entities stereoplotted from 
the ADS40 1 st generation of the Susa Valley 
According to our methodology, it was expected that a 1:10000 
map scale (figure 2) would be extracted from these images. 
Map entities 
Group 
A 
Group 
B 
Group 
C 
Road and railway 
96% 
4% 
0/9 
P 
Buildings, urban 
furniture, technical 
buildings 
100% 
0% 
0% 
P 
Water, rivers, 
channels, water 
works, etc. 
100% 
0% 
0% 
P 
Energy, material, 
fluid pipelines 
95% 
5% 
0% 
P 
Man-made Territorial 
divisions 
100% 
0% 
0% 
P 
Break lines 
100% 
0% 
0% 
P 
Vegetation 
100% 
0% 
0% 
P 
TOTAL % 
98% 
2% 
0% 
P 
Table 2. Map entity levels and sub-levels 
The analysis of the results is summarized in table 2. The 
performed analysis has confirmed the expectations. The colour 
images helped to detect different objects and to distinguish, 
according to their colour, different entities, such as stone walls 
from brick walls. 
However some map details were not metrically plotted as 
requested in technical specifications because of their reduced 
dimensions in the images. For example the sky-lift pylons in 
figure 3 are shown as they appeared at zoom 1:1: this kind of 
entity is obviously difficult to detect and even more difficult to 
plot. 
The GSD 0.62 m can, to a certain extent, be considered the 
maximum suitable dimension in 1:10000 map production. In 
general, a maximum GSD of 0.60 m is suggested for this map 
scale. 
Figure 3. Sky-lift pylons in a ADS40 image (zoom 1:1) 
2.2 ADS40 2 nd Generation 
This sensor acquired images during two flight performed at 
different altitude over the city of Romanshom (Switzerland). 
One flight was performed at about a height of 1000 m and with 
a GSD of 0.10 m. The second flight, which was flight at an 
altitude of 2000 m, instead had a GSD of 0.20 m. 
Both flights acquired good quality images. An example of the 
images from the first flight images is shown in figure 4 while an 
example of the 0.20 m GSD images is given in figure 5. 
Figure 4. Urban area acquired by ADS40 2 nd generation, 
GSD=0.10 m (zoom 1:1,4:1)