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|標題:||ERS-1 SAR與Landsat TM組合影像應用於埔里與南投地區之地覆分類|
Land Cover Classification with Conbination of ERS-1 SAR and Landsat TM Data over Pu-Li and Nan-Tou Areas
山區與南投平地地覆之辨識能力，而最終目的則在瞭解ERS-1 SAR與Landsat TM的組
In remote sensing, each of the radar and the optical sensor has its own advantages over the other. Clearly the synergism of radar data and visible and reflected infrared for land resource applications is becoming of greater practical importance. The objective of this study was to investigate how ERS-1 SAR could effectively discriminate land cover types in Pu-Li mountain area and Nan- Tou flat land area and eventually to determine if the synergism of ERS-1 SAR and TM data could be achieved to improve significantly the classification accuracies of land cover types in these two areas. Statistical analysis and preliminary interpretation of the radar backscatter from different land cover types was conducted to establish a look-up table for surface features and their signatures on the SAR image. Multispectral classifications using the maximum likelihood classifier and accuracy assessment were performed both on the composite images and on the TM images. The results showed that the classification accuracies of the composite images over Pu-Li and Nan-Tou areas were decreased slightly with the addition of SAR C band. In the mountain area, radar backscatter was dominated by topographic slope due to ERS-1 SAR(s high depression angle (small local incidence angle). The within-category variance of each land cover type became greater than among-category variance due to the topographic effects introduced by the high depression angle. This made ERS-1 SAR C band difficult to discriminate land cover types in Pu-Li area. In the flat land area, ERS-1 SAR could not discriminate land cover types effectively, since it operates on a single frequency and on a single polarization mode and this frequency is not optimal for land cover classification. Therefore, ERS-1 SAR has poor discrimination ability for land cover types in these two areas. Nevertheless, there may have a high possibility to improve land cover mapping with the synergistic use of SAR and visible/infrared data if multi-frequency, multi-polarization SAR data with an appropriate depression angle that can minimize topographic effects are used. The follow-up studies will be to investigate how to determine an optimal SAR band combination.
|Appears in Collections:||森林學系|
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