User Manual - pancroma

accordance with the accompanying Landsat metadata) without loss of precision.DNs have only 8 bits of dynamic range and this is of course limits the precision ofthe TOA reflectance values derived from them.Using the LSA with surface reflectance data proceeds almost exactly as with thecorresponding DN bands. Select ‘File’ | ‘Open and open either six Landsatsurface reflectance band files, band1 (Blue), band2 (Green), band3 (Red), band4(NIR) band 5 (SWIR) and band 7 (LWIR) or alternatively include the thermal IR(TIR) band by opening band1 (Blue), band2 (Green), band3 (Red), band4 (NIR)band 5 (SWIR) band6 (TIR) and band 7 (LWIR). Now select ‘Spectral Analysis’ |‘Landsat Spectral Analyzer’ | ‘Six/Seven Reflectance Bands’ | ‘Manual Method’.The Spectral Criteria Form will be displayed as described above. The settingsare made the same as described previously. After accepting (clicking ‘OK’) theLSA will compute the image as before.A couple of notes about the TIR band. Thermal data is archived in I16 format asscaled degrees Celsius. The integer values should normally be multiplied by ascaling factor of 0.01 to convert the I16 data to degrees Celsius. PANCROMA TMinstead multiplies the data by a factor of 0.0001, the same scale factor as is usedto convert the I16 band data to surface reflectance. The advantage of doing thisis that the data stored in the thermal band is of the same order of magnitude asthe reflectance data, which simplifies data display. Since the band data can beconsidered as orthogonal vectors, it is not possible to combine them as scalarvalues anyway so it does not really matter how they are scaled from a processingstandpoint. However, if thermal ground truthing data is used to calibrate or verifythe results, the measured temperatures should be divided by 100.0 in order tomatch the values that PANCROMA TM computes.Note that processing times for surface reflectance data will take somewhat longerthan using DN band data. This is because the integer reflectance files are twiceas large as the corresponding DN band files, and decoding the 16 bit data andconverting it to float type takes longer for each file.Another application for Landsat reflectance data is combining channels to maketrue color or false color RGB composite images and even pan sharpenedimages. Because atmospheric effects are removed, this data can make imagesof exceptional quality. Example RGB color composite and pan sharpenedimages of the massive Chuquicamata mine in northern Chile made with Landsatsurface reflectance data are shown below.243