EuroSDR Projects - Host Ireland

• ADS40_1 and 2: Results for both images (Figure 3) have only been produced by Zhang after
down sampling them by a factor of four, thus not making full use of the available information. The
results for both are not practically relevant, but one can observe that the performance for the easier
rural image 1 is better than for the suburban image 2 where less than one third of the roads are
correct and less than half of the roads have been found.
Figure 3: ADS40_1 – Zhang (left), ADS40_2 – Zhang (right); colors cf. Fig. 1
• Ikonos1, 2, and 3: Gerke_W was the only approach for which we received results for all three
Ikonos images. Bacher who, in this case, basically uses the same approach as Gerke_W, but with
different parameter settings, only processed Ikonos3. The results for Ikonos 1 (Figure 4) and 3
have been approximately as expected. Completeness and correctness for the suburban, i.e., more
difficult Ikonos1 are lower than for the rural Ikonos3, with Bacher (Figure 5) achieving a more
complete, but also more incorrect result. Ikonos 2 has proved more difficult than expected as
demonstrated by the results (Figure 4). It is a rural scene with medium complexity, but a
combination of different complications such as trees alongside the roads and small and elongated
fields together with the low quality of the image possibly due to haze in the atmosphere resulted in
a very high number of false hypotheses for roads, bringing down the correctness to a mere 10%.
Reasons for an inability to process the larger Ikonos scenes were apparently twofold. First, because of
missing functionality for processing the whole image in patches which are then combined into one
solution, intermediate results just exceeded the available memory. Second, even if this had not been
the case, the time it takes to process the image together with the need to adapt the parameters to all
variations in the larger scenes, meant these images required too much effort for most people. One gets
a hint for the latter when comparing the results for the whole scenes Ikonos1 and 3 with the much
better results for the relatively representative sub-areas, described below.
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