A Soil and Impervious Surface Adjusted Index for Urban Impervious Surface Area Mapping

Abstract

Index-based methods are widely applied to urban impervious surface area (ISA) mapping, but the confusion between ISA and soil remains unsolved. In this article, the near-infrared (NIR)-blue bands were selected as feature space by analyzing the spectra from the US Geological Survey spectral library, and a simple impervious surface ratio index (ISRI) was developed by shifting the NIR-blue coordinate origin toward the convergence point of the fitting lines of ISA and soil. The ISRI was then validated for threshold simulation, separability, and correlation analysis. Results demonstrated that ISRI had a good performance for ISA mapping in four cities in China with different geographic environments, with all extraction accuracies all above 90%. ISRI had a high separability between ISA and soil and was better than other indices (normalized difference built-up index and biophysical composition index). Further, ISRI has a close relationship with the ISA proportion. Therefore, ISRI would be a simple and reliable index for urban ISA mapping.

Analysis of the Coupled Assessment of Ecosystem Health and Its Spatial and Temporal Evolution in Fujian China

“…Due to the complexity of ecosystems, a single index often does not provide a comprehensive and effective assessment and description of ecosystems [13]. Remote sensing technology has the advantages of wide-scale monitoring, periodicity and real-time assessment, and is widely used for ecosystem health degree evaluation, while remote sensing-based ecological index methods use principal component analysis coupled with NDVI [14,15], Wetness Index (WET) [16], dryness (the Normalized Difference Based built and Impervious Surface Index, NDBSI) [17,18] and heat (Land Surface Temperature, LST) four ecological indicators, which can systematically evaluate the health of regional ecosystems [19,20]. The biggest problem in the Anthropocene is how to deal with the coupling of "society-economy-environment", and society, economy and environment have become an inseparable research whole.…”

“…The RSEI [28,29]index is an index based on remote sensing information and natural factors established based on greenness, humidity, heat and dryness indicators. The vegetation normalized index [14] was used for the greenness index, the land surface temperature for the heat index, the humidity index [16] for the humidity index, and the dryness index [17,18] for the dryness index with the following equations ( 1)-( 3).…”