A METHOD FOR BUILT-UP AREA EXTRACTION USING DUAL POLARIMETRIC ALOS PALSAR

Abstract. Mapping of the built-up area is a task of exigency as the area supports varieties of anthropogenic activities and is important for several ecosystem services. The task becomes more complicated owing to similarities in spectral characteristics with the bare soil. A new radar-based approach is proposed using Synthetic Aperture Radar (SAR) HH/HV dual polarized L-band ALOS PALSAR data. Sigma nought (σ⁰) values are extracted from the HH and HV polarized data. HH and HV sigma nought images are ratioed and normalized and then equated together in a unique combination to generate an index that is developed, cross-checked and validated over multiple regions, with simultaneous inputs from Ground truth (GT) data. Maps developed using the index is classified into built-up and non built-up areas, where the results show that the proposed method is very effective for built-up area detection. The approach adopted in this study is acceptable due to its high accuracy, simplicity and reliability; and hence easy to replicate.