A. BAUDOIN, R. BROSSIER 
INSTITUT GEOGRAPHIQUE NATIONAL 
Aérodrome de Creil 
60107 CREIL CEDEX 
FRANCE 
  
2 that | SUMMARY 
contri- ES 
As early as 1979 the IGN-F has closely participated to the elaboration of 
the SPOT programme and more precisely to the possible cartographic applications 
the | of its space data. 
(unknown | 
. Besides | The main performances of the SPOT system will briefly be recalled to your 
uickly | memory, more especially those directly concerning cartography i.e. accessibility 
and stereoscopy. 
DENT 
  
= | The second part treats first with SPOT data and the various degrees of the 
ecision obtainable precision, secondly with their applications to the making of new maps 
that or the way of up-dating them. : 
INTRODUCTION 
NT ILU 
as ; The IGN-F has been using space data for over ten years as well in geodesy 
pitation than in remote sensing applications, as soon as the first imagery produced by 
till te U.S Earth observation satellites has been available in 1972. Since the LANDSAT 
ntry with images have been used as much as for the French needs (allowing the up-dating 
end of the | survey of vegetation on the maps at 1:100 000 scale for instance) as for foreign 
als, planed ones (spatial maps at 1:250 000 scale for Middle East Countries). 
; ; However the resolution allowed by the LANDSAT MSS scanning sensor (about 
atic exploi- 80 m) limits to little scale maps the field of applications of this imagery. 
photogram- 
ithout | A better instrument making possible the mapping of the Earth from Space 
data is needed by many cartographers who ask for a finer resolution as well as 
a finer quality of the imagery with stereoscopic possibilities. These conside- 
rations incite the CNES to study a new satellite able to register the various | ij 
Earth data needed by the different sorts of users in their specific missions | 
(inspecting, inventorying, crops prevision, geological prospection, mapping, etc) 
As the project did not get the agreement of whole Europe, the French government 
decided in 1978 to realise it alone. 
The programme has been called SPOT (Earth Observation Probative System). I 
The importance of the cartographic possibilities of the SPOT system gave 
the IGN-F the possibility of collaborating very closely with the CNES -actually | 
the leader of the study- and to create in TOULOUSE a centre of Rectification of | 
Space imagery called CRIS (Space Imagery Rectification Centre). These images so 
pretreated at various degrees of precision will give the data necessary to realise 
quicker the planimetric revision at medium scale, to make new plotting at 1:100 000 
scale in foreign countries and to create new products. 
I - CHARACTERISTICS OF THE SPOT SYSTEM 
  
The SPOT system is composed of a satellite and on the Earth several 
organisations which permit to access to Space data and to interpretate them. 
1. THE SATELLITE 
The satellite is composed of a multivalent platform which can be 
adapted to various type of missions and a payload. composed of two 
HRV sensors. 
The orbit parameters given by Figure 1 correspond to the criteria 
| of an observer on the Earth. It is an almost circular polar and 
heliosynchronous orbit : the satellite passes over the same location 
| at the same solar hour. 
The HRV (High Visible Resolution) sensors representing the payload use 
the principleof electronic scanning eliminating so any moving piece. 
In the focal plan of the instrument are placed strips of detectors 
(CC D) so to give two types of imagery 
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