3. RESULTS AND ANALYSIS
Figure 5 illustrates the output from the multi-layer
classification process. While figure 6 and 7 represents the edge
detection map for the study area and the candidate parcels as
buildings respectively.
d000
| Shadow
Building
cis 2e
2 Asphalt
Figure 5. Classification results for the proposed band ratios
edge map after spur
E
A.
Figure 7. Candidate parcels as buildings
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B7, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
It is quite clear from figure 7 that the algorithm mixed between
shadow and vegetation areas with buildings. The integration
part will account for this confusion as vegetation and shadow
areas are well defined in the multi-layer classification part. A
quantitative analysis for the building class (extracted) were
done by comparing the number of buildings in the original
image by the complete detected number of buildings being
detected in the classified images either from pixel-based output
or from the final integrated output. Table 2 summarizes the
comparison results.
Pixel-based 12 9 1 22
result
Accuracy 85.7 83.9 8.8 45,8
%
Proposed 14 16 11 41
method
Accuracy 189 94.1 64.7 85.4
%
Table 2. Comparison of results
The final result after integrating the two approaches is in figure
Figure 8 final classification results
4. CONCLUSION
A method using both pixel and object-based classification
process was introduced to extract six land covers; vegetation,
water, buildings, shadows, asphalt roads and bare soil.
WorldView-2 imagery over Ismailia city, Egypt was used. The
classification accuracy for five classes out of six was
acceptable, and it was enhanced for buildings’ class.
Specifically, buildings’ class accuracy was enhanced from
45.8% to 85.4% using this technique. This technique was
applied for many other parts of the large scene, Ismailia city,
and the results showed great potentials of using this method in
enhancing the percentage of the detected buildings.
5. ACKNOWLEDGMENTS
This work was supported in part by research funds from
TECTERRA Commercialization and Research Centre, the