Textbook in PDF format This book systematically and comprehensively introduces concepts, theories, principles, and applications of Thermal Infrared (TIR) imaging spectral techniques and TIR remote sensing. It introduces in detail algorithms, techniques, and methods for processing and analyzing TIR data, including radiometric calibration and atmospheric correction in TIR region, retrieving land surface emissivity and temperature (LST) from various TIR data, and downscaling LST and TIR radiance spatiotemporally. Focusing on TIR-RS application orientation, this book introduces state-of-the-art techniques and methods applied in areas such as hydrology, biomass burning, urban thermal environment, and other areas of interest