preliminary investigation of the airborne SAR 
has shown that cutblocks and new roads are 
distinguishable by their texture from the 
forest stands. 
Investigations of the effect of radar incidence 
angle over forested sites have suggested that 
higher angles in orbital SAR imagery are 
preferred over steep angles to accentuate 
land cover information (Ahern and Raney, 
1993; Rossignol and Ahern, 1992). The 
SAR data used in the present study will serve 
to further examine the influence of incidence 
angle for SAR forestry applications. 
During the initial stages of this project, it was 
planned that RADARSAT mapping 
capabilities and accuracies would be tested 
with simulated RADARSAT Fine Resolution 
Mode data. After some reflection, the 
authors determined that absolute mapping 
accuracies of RADARSAT data could not be 
reliably estimated with simulated data. 
The imaging geometry of the input data for 
the simulations (airborne SAR data) is 
significantly different than what will be 
available with RADARSAT. Therefore, the 
airborne SAR data cannot effectively depict 
RADARSAT's geometric characteristics. 
Hence, the simulated RADARSAT data 
analysis was limited to a qualitative 
assessment of the sensor's ability to detect 
forest harvesting features. 
Figure 1 and Figure 2 show the imaging 
geometries of the RADARSAT Fine 
Resolution Mode and the CCRS C/X SAR 
Narrow Mode data. The lower altitude of the 
airborne C/X SAR sensor produces a 
significant variation of incidence angle from 
the near to the far range within a single 
image (35? to 76? in our case). Near to far 
range incidence angle variation in orbiting 
SAR's are more subtle. 
450 
  
RADARSAT Fine Resolution Mode 
Incidence Angles of the five 
Fine Resolution Mode 
Positions 
  
eX T N ie 
Ag 
> 
45 km 
km 
  
  
  
Figure 1 RADARSAT Fine Resolution Mode Imaging 
Geometry and Incidence Angle Positions 
  
a 0 
Near Edge Far Edge 
F1 36.9? 40.19 
F2 39.39 42.39 
F3 41.6? 44.29 
F4 43.5° 46.0° 
F5 45.39 42.92. 
CCRS C/X SAR 
NARROW SWATH MODE 
| 
SN. ^ 
i— - 18 km — 
  
  
  
Figure 2 CCRS C/X SAR Imaging Geometry and 
Incidence Angles 
The ortho-rectification process is being 
attempted with the ERS-1 Roll Tilt Mode 
image to develop an operational method for 
orbital SAR DEM correction. However, the 
accuracies of the ortho-rectified ERS-1 data 
are not considered to be fully representative 
of RADARSAT's attainable accuracies due to 
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