A Functional Model for Determining Maximum Detectable Deformation Gradients of InSAR Considering the Topography in Mountainous Areas

The maximum detectable deformation gradients (MDDG) for interferometric synthetic aperture radar (InSAR) technology is important for the selection of SAR images and processing algorithms to perform accurate slope displacement monitoring, which is strongly influenced by terrain factors in mountainous areas. In this article, a functional model is proposed to determine the MDDG of InSAR with respect to arbitrary slope gradients/aspects and wavelengths. Based on this model, regional MDDG characteristics are explored and compared in Mao County, Sichuan Province, China. The MDDG distribution regarding Sentinel-1, ALOS-2/PALSAR-2, and TerraSAR-X SAR satellite data using arbitrary slope gradient/aspect are derived. Furthermore, the MDDG from variable satellites for three different bands (X/C/L-band) are compared and the influence factors with respect to the wavelength and resolution on MDDG are discussed. The proposed model is helpful in selecting SAR data or processing algorithms based on calculated MDDG, in the meanwhile, it has significant implications for understanding and analyzing real slope displacement monitored by InSAR regarding different SAR images in mountainous areas.