(1)Scientific significance of urban impervious surfacesAmong urban land covers, urban impervious surfaces mainly refer to the built-up areas, including pavements and rooftops, that can be made up of diverse materials, such as asphalt, concrete, plastic and metal materials. Conventionally, urban impervious surfaces have been identified as a critical indicator for the process of urbanization and for the environmental impacts of urbanization (Arnold and Gibbons, 1996; Weng, 2001; Wu and Murray, 2003; Zhang et al., 2015). They were commonly used in lots of studies on environmental consequences of urbanization (Arnold and Gibbons, 1996; Bannerman et al., 1993; Schueler, 1994; Sleavinet al., 2000), hydrological, atmospheric and environmental models to simulate and study the urban hydrological process (Arnold et al., 1982; Espey et al., 1966; Jacobson, 2011; Seabum, 1969; Yang et al., 2010), urban atmospheric process and urban climate change (Hu et al., 2014; Ooi et al., 2017), urban solar energy balance, urban land surface temperature and the urban heat island (Lu and Weng, 2006; Schueler, 1994; Slonecker et al., 2001; Weng et al., 2006; Yuan and Bauer, 2007), as well as socio-economic studies such as measurement of urban growth, estimation of population distribution, and variation of housing prices (Wu and Murray, 2003).(2)Urban land cover classification from synthetic aperture radar(SAR) dataNumerous studies have focused on the urban land use and land cover (LULC) mapping using various polarimetric SAR data. Since the active and side-looking SAR is sensitive to the dielectric and geometric properties of urban land surface such as structure and surface roughness, SAR data provided complementary information for LULC (Calabresi, 1996; Henderson and Xia, 1997; Stasolla and Gamba, 2008; Zhang et al., 2012; Zhang et al., 2014). With a number of studies exploring SAR data using their backscattering and polarimetric information, the diversity and complexity of LULC were identified and reported (Dekker, 2003; Gamba and Aldrighi, 2012; Guo et al., 2014; Hu and Ban, 2012; Majd et al., 2012; Niu and Ban, 2013; Tison et al., 2004; Voisin et al., 2013; Zhang et al., 2012; Zhang et al., 2016; Zhang et al., 2014).
(1)Scientific significance of urban impervious surfacesAmong urban land covers, urban impervious surfaces mainly refer to the built-up areas, including pavements and rooftops, that can be made up of diverse materials, such as asphalt, concrete, plastic and metal materials. Conventionally, urban impervious surfaces have been identified as a critical indicator for the process of urbanization and for the environmental impacts of urbanization (Arnold and Gibbons, 1996; Weng, 2001; Wu and Murray, 2003; Zhang et al., 2015). They were commonly used in lots of studies on environmental consequences of urbanization (Arnold and Gibbons, 1996; Bannerman et al., 1993; Schueler, 1994; Sleavinet al., 2000), hydrological, atmospheric and environmental models to simulate and study the urban hydrological process (Arnold et al., 1982; Espey et al., 1966; Jacobson, 2011; Seabum, 1969; Yang et al., 2010), urban atmospheric process and urban climate change (Hu et al., 2014; Ooi et al., 2017), urban solar energy balance, urban land surface temperature and the urban heat island (Lu and Weng, 2006; Schueler, 1994; Slonecker et al., 2001; Weng et al., 2006; Yuan and Bauer, 2007), as well as socio-economic studies such as measurement of urban growth, estimation of population distribution, and variation of housing prices (Wu and Murray, 2003).(2)Urban land cover classification from synthetic aperture radar(SAR) dataNumerous studies have focused on the urban land use and land cover (LULC) mapping using various polarimetric SAR data. Since the active and side-looking SAR is sensitive to the dielectric and geometric properties of urban land surface such as structure and surface roughness, SAR data provided complementary information for LULC (Calabresi, 1996; Henderson and Xia, 1997; Stasolla and Gamba, 2008; Zhang et al., 2012; Zhang et al., 2014). With a number of studies exploring SAR data using their backscattering and polarimetric information, the diversity and complexity of LULC were identified and reported (Dekker, 2003; Gamba and Aldrighi, 2012; Guo et al., 2014; Hu and Ban, 2012; Majd et al., 2012; Niu and Ban, 2013; Tison et al., 2004; Voisin et al., 2013; Zhang et al., 2012; Zhang et al., 2016; Zhang et al., 2014).
