1. 
Concluding remarks 
The most promising Landsat MSS data for multitemporal studies of 
earth resources can only be obtained if careful consideration is given to 
following factors: cloud cover, image quality, snow cover, bio- 
climate and sidelap when analysis is done both visually as well as 
digitally. 
Co-ordination, standardization and exchange of data of the various 
distribution centres of space imagery and documentation is highly 
recommended. The Eros Data Center's initative for a worldwide 
reference system (WRS) is appreciated. Further consultation of the 
parties concerned ( recieving stations, distribution centres, 
major users and co-ordinating agencies such as FAO ) will be needed. 
The above efforts may lead to an international data base” for space 
imagery and documentation to which all receiving stations and 
distributions centres ought to be connected. The contribution of Fàrthnet 
(ESA) is a good step in this direction, but it should iot be limited to 
Europe and Northern Africa only. 
Major users should have à terminal connected to the above 
common base of space imagery and documentation in order to 
speed up the time consuming iterative process of selection of 
imagery as outlined in this paper. 
* Reference is made to the first FAO Consultation Meeting, Rome, Nov. 1977 
for the set up of a World Information System of Space Information (WISI).