I contrast | ground resolution | 
3.8 
1 
21.6 
m 
3.3 
1 
22.4 
m 
2.3 
1 
24.5 
m 
1.9 
1 
27.7 
m 
1.4 
1 
52.0 
m 
8: ground resolution of panchromatic 
SPOT images depending upon 
image contrast 
The visibility of objects is not limited by the ground resolution, it is also depending 
upon contrast, size, shape and systematic. Especially linear features like roads can 
be seen if they are smaller than the pixel size on the ground. 
The completeness of maps based on space images has been investigated in the 
University of Hannover. It was not possible to have usable images of all sensors in 
the same area, so there are some limits of the comparability of the achieved 
results. 
sensor 
area 
MC 
Sittensen 
LFC 
Helmstedt 
SPOT ms 
Stadthagen 
KFA 1000 
Stadthagen 
highways 
100 
100 
roads 
57 
93 
98 
98 
railroads 
96 
88 
field pathes 
13 
90 
30 
35 
drainage 
28 
50 
51 
streets 
37 
55 
table 9: 
completeness of 
mapping in scale 
1 : 50 000 
( % ) 
The results listed in table 9 have to be analysed carefully. In general, caused by the 
resolution, the results obtained with LFC have been better than with MC. The more 
poor results for the railroads have been influenced by a disused line in a forest. In 
SPOT and KFA images more detailes have been identified. Only in the case of 
streets in the build up areas there is an advantage of the KFA against SPOT. 
Close to Hannover in the area of Wunstorf maps 1 : 25 000 have been made based 
on a high altitude photos (RMK) (photo scale 1 : 123 000), KFA 1000, panchromatic 
and multispectral SPOT images (see fig. 2 - 6). 
sensor 
SPOT pan 
SPOT ms 
KFA 1000 
table 10: 
completeness of mapping 
streets 
97 
98 
77 
railroads 
100 
100 
100 
in scale 1 : 25 000 
creek 
91 
100 
91 
test area Wunstorf 
build up area 
94 
89 
100 
l % l 
In spite of 20m pixel size for multispectral SPOT images in relation to 10 m for 
panchromatic SPOT images, the object identification is not so much different for 
both. In the multispectral images the detailes in build up areas cannot be seen so 
clearly. Opposite to this, water courses can be identified better which is caused by 
the very good contrast of water in the near infrared. The advantages of the better 
resolution of panchromatic images can be combined with the better spectral 
132