International Archives of Photogrammetry and Remote Sensing. Voi. XXXII Part 7C2. UNISPACE III, Vienna, 1999 
17 
I5PR5 
UNISPACE III - ISPRS Workshop on 
“Resource Mapping from Space” 
9:00 am -12:00 pm, 22 July 1999, VIC Room B 
Vienna, Austria 
Figure 5: Annual Update Rate 
ISPRS 
Again, the developing continents have much smaller update 
rates than Europe or North America. 
It becomes clear that the existing map technology based on 
aerial photography and ground methods is too slow to provide 
the required data sets. Thus satellite systems must be utilized. 
6. Present Capabilities of Optical Satellite Systems 
Geostationary low resolution satellites such as G.MS, Insat, 
Goes and Meteosat offer images of the earth’s surface every 30 
min at 5 km ground pixels. NOAA satellites offer 1 km 
resolution at least twice per day. Such data are ideal for global 
monitoring. 
Resource satellites such as Landsat, Spot, JERS and IRS 1A and 
B offer medium resolution data between 10 and 30 m ground 
pixels several times per year. 
The latest development are high resolution satellites such as 
IRS-1C and MOMS with about 5 m ground pixels without the 
present capability to obtain a global coverage as yet (see figure 
6). 
Experiences with these systems have shown that the use of 
satellite images for mapping is 
■ at least four times cheaper than using conventional 
methods 
■ but that at present resolutions quality standards must be 
relaxed 
■ visual interpretation of these images is still more effective 
■ but GIS integration is of advantage 
■ cloud cover is still a handicap opening ways for radar 
satellites such as JERS-1, ERS 1,2 and Radarsat. 
Even 5 m resolution systems cannot compete in quality to aerial 
photography with 1 m resolution in 1:25 000 mapping (see 
figure 7).