1. ROAD EXTRACTION IN URBAN AND RURAL ENVIRONMENTS EXPLOITING A DUAL-BAND SAR SYSTEM P. Gamba (1) , G. Lisini (2) , D. Luebeck (3) (1) Università degli Studi di Pavia (2) IUSS, Pavia (3) Orbisat, Sao Jose dos Campos
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4. Does radar frequency matter? Green arrows point to roads in P-band data that are not visible in X-band data. P-band X-band
5. Dual-band SAR may help ... Dual-band SAR systems are well suited for vegetation analysis X-band is more prone to be scattered by trees and foliage P-band , due to its longer wavelength, is able to pass through vegetation and to better detect underlying roads and other man-made or natural objects
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7. The general idea … A fusion methodologies able to exploit road extraction from an airborne dual-band SAR acquisition … Multi-frequency SAR data Road network fusion … N th band road extraction 1 st band road extraction 2 nd band road extraction
9. SAR road extraction methodology Road detection Road extraction Road network MRF optimization Network regularization HR SAR Final road network Multi-scale feature fusion Junction-aware MRF model Perceptual grouping M. Negri, P. Gamba, G. Lisini, F. Tupin, “ Junction-Aware Extraction and Regularization of Urban Road Networks in High Resolution SAR Images ” , IEEE Trans. on Geoscience and Remote Sensing, vol. 44, n. 10, pp. 2962-2971, Oct. 2006.
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12. Road candidate area extraction Remote Sensing Group “ min radiance” thresholded “ min radiance” output
16. Road candidate extraction Final segments The approach is efficient, with the only drawback of reducing curvilinear roads to chains of linear segments.
17. Perceptual grouping step The procedure is based on Perceptual Grouping Concepts and allows connecting segments where reasonable, based on their mutual positions 1° 2° 3° 4° 5° 6°
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20. First test site results Remote Sensing Group Original P-band image P-band extraction Original X-band image X-band extraction
21. First test site results Remote Sensing Group final results after the fusion step (option 1b) final results after the fusion step (option 1a) final results after the fusion step (option 1c)
22. Quantitative evaluation Main outcomes: + due to the presence of vegetation, P-band results are better than X-band ones ; + the fusion of both extractions increase in the completeness and correctness index values; + the real improvement in the road extraction results is for the roads outside the human settlement . X-band extraction results P-band extraction results Fusion results (1a) Fusion results (1b) Fusion results (1c) Completeness 0.16 0.67 0.73 0.73 0.64 Correctness 0.78 0.79 0.74 0.78 0.93 Quality 0.15 0.56 0.60 0.61 0.54 Redundancy -0.07 -0.03 0.06 0.06 0.03
24. Best result for Paragominas Final results after the fusion step (option 1b) Quantitative indexes for the road extraction results in the Paragominas urban area test site P-band extraction results Fusion (option 1a) Fusion (option 1b) Fusion (option 1c) Completeness 0.64 0.92 0.92 0.84 Correctness 0.55 0.41 0.45 0.95 Quality 0.42 0.41 0.43 0.63 Redundancy -0.02 0.05 0.05 0.03
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