User Manual - pancroma

Landsat 7 Surface TemperatureThe Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+)sensors acquire temperature data and store this information as a digital number(DN) between 0 and 255 inclusive in the Thermal Infrared (TIR) bands. It is possibleto convert these DNs to degrees Kelvin using PANCROMA TM Surface Temperatureutility. PANCROMA TM uses the method specified in the Landsat 7 Science DataUsers Handbook, first converting the DNs to radiance using the bias and gain valuesspecific to the Landsat band 6, 6a or 6b TM or ETM bands. It then uses the ThermalBand Constants specified in the handbook. The temperatures can be written asFLOAT types to file, displayed as a scaled grayscale image or as a color contourplot.T = K 2 / ln( (K 1 /L λ )+ 1)To use the utility, open a Landsat TIR band by selecting ‘File’ | ‘Open’. Thenselect ‘PreProcess’ | ‘Compute Surface Temperatures’ | ‘Landsat 7’. (Note thatonly TIFF and L1G format is accepted by this utility.) A data entry screen will bedisplayed. You will be prompted to select how the data will be output. You cancheck boxes to direct PANCROMA TM to save a data file, display a grayscaleimage or display a color contour plot. The band number track bar is visible but isnot adjustable as the temperature computation is only valid for band 6 input files.However the Graphics Image Scale Factor can be used to attenuate thegrayscale image output, since the temperature is reported in degrees Kelvin andwill typically exceed the maximum allowable grayscale channel value (255) if not.The default setting is 0.5. Note that you must check either the ‘Landsat ETM+’ or‘Landsat TM’ radio button as the band 6 gains are different for the two Landsattypes. If your input file is a Landsat ETM+ type, PANCROMA TM willautomatically detect whether the input file is a high gain (suffix 61) or low gain(suffix 62) type so that the correct gain and bias coefficients will be used.187