International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B-YF. Istanbul 2004
2004
Periodic and random noise can be reduced by increasing the Since atmospheric haze directly affects the histogram of the
ratio of signal to noise (figure 9) (Abreu ef al 1996, Hu et al image (shift and compression), histogram transformation
1997, Ishihara ef al 1999). techniques are employed to eliminate it(figure 11) (Mekler &
could Kaufman 1990).
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Figure 9. Image No.3 (PAN) after noise removal
Fundamentally band missing problem could not be eliminated :
st be ange ay Ssing D d $C maniac Figure 11. Image No.5 (LISSIII) after haze removal
jacent or improved because of significant loss of data but sometimes
replacement of values obtained from the correlaton equation to ; :
à Y 3 4.3 Geometric Quality Improvement
other bands can be useful however not appropriate for all of the
features. Geometric Quality improvement methods are listed irtable 6.
4.2 Atmospheric Quality Improvement = ; :
p Q y mp Geometric Manual Automatic
In table 5, removal methods of atmospheric effects are QE Improvement Improvement
mentioned. Ha Band to band Conformal Sub pixel Edge matching
misregistration | Transf. & (Canny 1986,Tao &
Atmospheric Manual Statistical Resampling Huan 1997)
Problem Elimination Elimination Image to map Rectification Rectification using
Cloud Cover Cloud masking by | Cloud masking by misregistration | using Manually | template matching
region growing clustering and selected GCP's technique
thresholding Table 6. Geometric Quality defects andimprovement methods
Haze Conventional HMM correction :
enhancements and stretching Using sufficient and well distributed GCPs, the image can be
(Andrews 1976) rectified properly and be matched to the overlaid vector map
Kats Table 5. Atmospheric problems andremoval methods (figure 12) (Buiten 1993).
ld be
them Once cloud is recognized, a nullor zero value is assigned to the
|
corresponding pixels(figure 10).
Figure 10. Image No.4 (AVHRR) Cloud masked
Figure 12. Image No.6 (MODIS) Image to map registration
