511 
better long term stability. 
Landsat 4 was also designed to interface with the Global 
Positioning System (GPS), when it becomes operational, 
which has the potential of providing extremely accurate 
ephemeris data, which in turn allows even better systematic 
error correction. 
Resampled Landsat 2/3 control points will be used to pro 
vide geodetic accuracy until the Landsat-4 control point 
library is established. 
On the ground, the improved low frequency (0 to 0.4 Hz) 
attitude correction information is used in the MSS image 
processing. In addition, improved automatic control point 
correlation techniques have been incorporated to help pro 
vide the geodetic accuracies specified. The ground pro 
cessing has explicitly taken advantage of the design 
features of the Flight Segment. 
Table 4 provides a summary of key geometric correction 
accuracy expectations. 
TABLE 4; SUMMARY OF GEOMETRIC CORRECTION ACCURACY 
GEODETIC RECTIFICATION 
• 03 PIXEL (90% OF THE TIME) 
• REFERENCED TO STANDARD MAP 
• ASSUMES ACCURATE KNOWLEDGE OF GROUND CONTROL POINT 
LOCATIONS 
• VERIFIED OVER AREAS WITH LITTLE TOPOGRAPHICAL VARIATIONS 
TEMPORAL REGISTRATION 
• 03 PIXEL (90% OF THE TIME) 
• ESTIMATED ON BASIS OF INSTRUMENT PERFORMANCE THAT 
IS EQUIVALENT TO ACTUAL PERFORMANCE OF MSS'S ON 
LANDSATS 1, 2 AND 3 
RADIOMETRIC CORRECTION 
The Landsat-4 radiometric calibration accuracy provides a 
factor of 2 improvement over the techniques used for 
Landsat 1, 2 or 3 processing. The Landsat-4 calibration 
algorithm uses both the MSS's internal calibration lamp 
data and scene content information to achieve ±1quantum 
level (out of 128) accuracy and to eliminate band-to-band 
striping effects. The algorithms have been fully evaluated 
using Landsat 1, 2 and 3 data.