Application of HyMap Image in the Environmental Survey in Shenzhen, China

摘要

Hyperspectral HyMap image with synchronous in-situ spectral data were used to survey the environmental condition in Shenzhen of South China. HyMap image was measured with 3.5m spatial resolution and 15nm spectral resolution from 0.44μm-2.5μm and corrected with Modtran5 model and synchronous solar illuminance and atmospheric visibility to the ground. The spectra of rocks, soils, water and vegetation were obtained by ASD spectrometer in reflectance. Both the fresh granite and eroded sandy soil was found with absorption at 2200nm± in-situ spectra, but the weathered granite and sandy soil have another absorption at 880nm～940 nm. Polluted water with high ammonia nitrogen and phosphorous and BOD_5 get the strongest reflectance at 550 ~570nm, while polluted water of high COD_(cr) and heavy metal ions content get the peak reflectance at 450～490nm. The in-situ spectra was resampled in wavelength range and spectral resolution to that of Hymap sensor for image classification with SAM algorithm, the unpaved granite among cement the paved mine pits , the newly excavated land surface and the eroded soil was mapped out with the accuracy over 95%. We also discriminate the artificial forest from the natural with the spectral endmember extracted from the image.