RRS DE 
  
  
SATELLITE-SENSOR SATELLITE-SENSOR 
TECHNOLOGICAL DATA ANCILLARY DATA 
i : 
- SATELLITE POSITION, VELOCITY 
RAW AND ATTITUDE 
DATA DTM GCPs 
- SENSOR POINTING GEOMETRY 
: 
> GEOMETRIC ASPZCTS OF A 
THE REMOTELY SENSED IMAGE 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
GEOMETRIC CORRECTION GCPs 
i 
CARTOGRAPHIC PROJECTION 
AND ACCURACY a 
  
  
  
  
  
  
  
  
  
  
  
  
  
fig. 3 Geometric preprocessing 
and the near edge with regard to the ground track. 
Considering the SPOT geometric resolution, the horizon- 
tal and vertical cartographic accuracy of the Italian Istituto fig. 
Geografico Militare and the errors due to digitization, analytic 
model and quantization, the existing maps at a scale 1:100,000 
are satisfactory for the SPOT satellite. In fact in the worst 
case the error in geographic location is less than one pixel. 
While the cost/benefit of the digitálization at a scale larger 
ade: 
than 1:50,000 is not really satisfactory for geometric correction e 
of the HRV images, maps at a scale less than 1:250,000 can be prog: 
used to improve the limited cartography of new areas. king 
The radiometric analysis needs a better knowledge of facts 
the HRV calibration techniques, Nevertheless our simulation pro- with 
gram gives useful informations for correcting the errors due to of ti 
exposure and illumination angles. In fact the height, the slope, tion 
the exposure and the atmosphere are considered. This 
Two different methods of atmospheric correction are Star 
used: one in the spectral range from the visible to the thermal 
IR (LOWTRAN) amd the other only in the thermal IR (RADTRA modi- 
fied) (Ref. 9, 10). This allows the simulation of the HRV as well 
as the Landsat Thematic Mapper, using multispectral scanners and 
spectroradiometers. 
28 
Pr = LZ Prec,