@ARTICLE\{IMM2020-07128,
    author       = "A. A. Nielsen and H. Skriver and K. Conradsen",
    title        = "The Loewner Order and Direction of Detected Change in Sentinel-1 and Radarsat-2 Data",
    year         = "2020",
    month        = "feb",
    keywords     = "Hermitian matrices, Complex covariance matrices, the Complex Wishart Distribution, polarimetric {SAR}",
    pages        = "242-246",
    journal      = "{IEEE} Geoscience and Remote Sensing Letters (Early Access June 2019)",
    volume       = "17",
    editor       = "",
    number       = "2",
    publisher    = "",
    note         = "Early Access June 2019. Matlab code in zip file.",
    url          = "http://doi.org/10.1109/LGRS.2019.2918636",
    abstract     = "When the covariance matrix formulation is used for multi-look polarimetric synthetic aperture radar (SAR) data, the complex Wishart distribution can be used for change detection between acquisitions at two or more time points. Here we are concerned with the analysis of change between two time points and the {''}direction{''} of change: does the radar response increase, decrease or does it change structure/nature between the two time points? This is done by  post-/co-processing the detected change with the Loewner order which calculates the definiteness of the difference of the covariance matrices at the two time points. We briefly describe the theory. Two case studies illustrate the technique on Sentinel-1 data covering the international Frankfurt Airport, Germany, and on Radarsat-2 data covering Bonn, Germany, and surroundings. We successfully demonstrate our {''}direction{''} of change approach to detected change areas."
}