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Figure 3: A diagram (not to scale) of Landsat Thematic Mapper satellite coverage (from 800 km at 15° FOV) in one scene compared 
with one frame of DMSV data (from 3 km at 37° FOV). 
To preclude changed surface conditions the Landsat and DMSV 
data acquisition times should be as close as possible. Some TM 
processing must precede correction. Firstly, the Landsat TM 
image is co-registered to the DMSV mosaic. Landsat TM data 
have a smaller dynamic range than DMSV data so needed to be 
scaled to approximately the same dynamic range. This is 
achieved by linearly regressing the Landsat TM data on the 
DMSV data. 
Each DMSV image has slightly different, illumination 
characteristics requiring a different correction. The coincident 
portions of the Landsat TM image and the DMSV image are 
extracted. Each band of this TM subset is subtracted from the 
corresponding band of the DMSV image. Figure 4 is the 
residual surface for, in this example a band 3 image from the 
Andoom area. This surface reveals differences relating to 
shading, and also shows as high frequency noise, the effects of 
the different spatial resolutions (2 m for DMSV versus 30 m for 
TM). 
A 25x25 moving-average filter was applied to each residual 
image to smooth the high-frequency effects. This reveals the 
shading surface that is then removed from that band of that 
particular DMSV image (Figure 5). 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996 
  
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