tic of real) antenna length in the direction of the platform movement. 
The returned radar signals may be digitized (or digitized and reconstruc 
ted for coherent radars) at arbitrary ground pixel sizes. For Seasat sa 
tellite images a pixel size of 25 m is usually chosen. But a detailed 
comparison of detectability of different objects with relation to reflec 
tance and topography has not yet been completed. But a preliminary analy 
sis suggests, that certain objects may have a resolution in excess of 
5 pixels. 
Airborne radar images (GEMS 1000) with a 10 m pulse flown over the test 
area Phoenix have demonstrated this. Geometric analyses using a dense 
control point distribution have reached a positional accuracy of ± 20 m 
standard deviation. For practical image mapping purposes, for example in 
Columbia, the achieved accuracies have been ± 300 m. 
In conclusion it can be said that sofar only the photogrammetric frame 
camera fulfills the requirement of topographic cartography. As far as 
the capacity of sensor data is concerned, frame camera imagery in color 
at a resolution of 30 Ip/mm has an information content of about 5.7 x 10^ 
pixels. It is superior to a Landsat scene with 7.4 x 10^ pixels by a fac 
tor of 77. Furthermore it can be seen from table 1, that the existing 
mission data do not deliver acceptable products for the systematic world 
wide Droduction of maps at scales between 1:50 000 and 1:100 000. 
Mission 
year 
fl ight 
alti 
tude 
image 
scale 
pixel 
size or 
photogr. 
resolu 
tion 
base to m = (iMm*) 1 / 2 
he j? ht Mm) y 
ratio 
m z 
t (m) 
authors 
LANDSAT-1, MSS 
LANDSAT-1, MSS 
" , RBV 
1972 
919 km 
3 369 000 
79 m 
80 m 
0.14 
53-115 
90-110 
413-536 
Welch.Lo /8/ 
Wong /9/ 
LANDSAT-2, MSS 
1972 
1 000 000 
79 m 
0.11 47- 95 
57-162 
Dowman, 
Mohartmad /2/ 
Sky1ab/S-190 A, 
c = 152.451 mm 
image format 
5.7 x 5.7 cm 
1973 
435 km 
2 850 000 
38-79 m 
0.26 
0.13 
54-102 
148 
398 
Welch.Lo /8/ 
Derenyi /1/ 
Skylab/S-190 B 
c = 457.411 mm 
image format 
11.5 x 11.5 cm 
1973 
435 km 
946 000 
17-30 m 
0.10 
0.10 15 
24-32 
500-675 
118 
Welch.Lo /8/ 
Keller /5/ 
Derenyi /1/ 
S0YUZ 22-30, 
MKF-6-camera, 
c = 125 mm 
since 
1976 
250 km 
2 000 000 
80 lp/m 
s 25 m 
- 
- 
SEASAT/RADAR 
1°78 
790 km 
theor. 
25 m 
- 
- 
GEMS 100 air 
craft radar 
12.5 km 
400 000 
theor. 
10m 
20-300 
- 
Konecny /6/ 
Table 1: Comparison of existing remote sensing missions 
Therefore a special mission aimed at cartographic interests is required 
to meet worldwide map demands. Another question has to be answered with 
regard to the type of map products for the future (e.g. orthophotos at 
regular intervals instead of conventional line map and their revision). 
376