Freiburg. The author also stated his familiarity with the area helped minimize confusion 
errors in this instance. This area of southwest Germany was also analyzed by Schmidt 
(1986) using VV-polarized X-band and L-band airborne SAR imagery. Depending upon the 
kind and groups of buildings present, the author found a more-or-less regular pattern that 
was easily visible on the X-band imagery. He also stated that isolated buildings were 
visible on the L-band scene. Unfortunately, no elaboration of these points were given. 
Sieber and Hartl (1986) classified land cover as one part of a SIR-B data observation 
experiment of the Freiburg, Germany, area. Using three paths or data takes they 
concluded that the steep incidence angle path (18 degrees) most significantly 
discriminated among classes that included settlements as a category. Incidence angle was 
considered to influence discrimination of land use classes more than the aspect angle. 
Aside from their mention of three cities no measure of accuracy or pixel/sample size was 
provided. 
Trevett (1986) reported on a project to survey land use and vegetation in Nigeria 
using a real aperture X-band airborne system and two look directions. In the northern arid 
regions of the country, villages could not be distinguished as the mud huts and grass roofs 
gave a signal response similar to the surrounding grassland. In the southern, more humid 
forested areas of the country villages were detected as the corrugated iron roofs of village 
dwelling gave a bright response that contrasted with the surrounding cover. 
Imhoff, et.al. (1987) used SIR-B imagery as part of a project to survey flood 
boundaries in Bangladesh. Using imagery with a 46 degree incidence angle a classification 
accuracy of 83 per cent for a combined settlement-dike category was attained. Data on 
omission errors (12 of 75 villages) and commission errors (13 agricultural areas were 
mis-identified as villages) were also included in the report. The authors stated that the 
raised elevation of the dikes and corner reflection from buildings against a background of 
nonturbulent water in the surrounding rice fields abetted visibility. Of note is the fact 
that these dwellings were also made of thatch. This contrast to the above mentioned 
results of Trevett in Nigeria indicates that the change in the terrain background may be a 
significant factor in settlement detection of the same building type. 
It is apparent that few investigations have given attention specifically to settlement 
detection and reasons for variation in the results. Fewer still provide quantitative data. 
Many include only a passing, general reference to settlement detection as a side light to 
broader or other-topic focussed research. In an attempt to broaden the understanding of 
these radar/terrain relationships, this study examines effects of environment 
(target/background contrast), radar incidence angle, and to some degree, look direction on 
settlement detection. 
STUDY AREA AND IMAGERY 
L-band, like-polarized (HH) SIR-B imagery of southern and southwestern Germany 
and northeastern France was recorded on three data takes in October, 1984. Relevant 
parameters of these data are listed in Table I. As can be 
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