UTILISATION OPERATIONNELLE DE LA TECHNIQUE D'AJUSTEMENT PAR BLOC 
DANS LA REALISATION D'UNE MOSAIQUE RADAR DE PRECISION 
RADAR BLOCK ADJUSTEMENT TECHNIQUE 
APPLIED TO PRECISION CARTOGRAPHIC MOSAIC IMAGERY 
par 
J.M. MONGET 
Ecole Nationale Supérieure des Mines de Paris 
Rue Claude Daunesse 
Sophia-Antipolis, 06565 Valbonne Cédex (France) 
J. NOEL - Y. PATOUREAUX 
Sodeteg - Division Espace 
9, Avenue Réaumur 
92350 Le Plessis-Robinson (France) 
R.D. REAGAN 
Aero Service 
8100 West Park . 
Houston TE 77063 (USA) 
ABSTRACT 
The Ministére des Mines et du Pétrole du Gabon has decided to undertake 
a global mineral assessment using radar and aerogeophysics survey in conjunction 
with geochemistry and ground geology mapping. 
Apart from the structural information acquired from radar, it was decided 
to rely on this instrument, in order to update the cartographic base of Gabon. The 
precision controlled mosaïcs of radar imagery have been produced using a block 
ajustment method. 
In December 1981, Aero Service Corporation conducted an airborne Synthetic 
Aperture Radar survey of Gabon for the purpose of producing a national radar mosaïc 
at a scale of 1:1,000,000 in addition to mosaïc sheets at a scale of 1:200,000, 
strip enlargements at 1:200,000, portions of strip enlargements at 1:50,000 and 
contact prints at 1:400,000. 
The survey covered the entire area of Gabon (approx. 267,700 square km) 
and all map products were to be accurate within 300 meters. The lack of suitable 
base maps made conventional map controlled compilation impractical and prompted 
Aero Service to employ block adjustment. This technique was particularly well suited 
in this case as there exist a suitable number of monumented control points forming a 
well distributed network throughout Gabon. 
  
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