User Manual - pancroma

When this option is enabled, a GeoTiff reflectance file is written immediately afterthe TOA Reflectance array is computed. The file is in the same format thatUSGS Landsat Reflectance data is archived in, namely sixteen bit integer (I16)format. A scaling factor of 100000 is applied to the data. This is ten timesgreater than the USGS convention but I found it was necessary in order for theoutput files to display adequately in other applications. You will have to take thisinto consideration if you import this format into another application.You can also elect to display the TOA reflectances as an image file. Since theTOA reflectances are small numbers compared to the DNs, they will need to bescaled in order to display properly. The default scale factor is 500. If the imagesare too dark, try increasing the scale factor. Black splotches on the image meanthat the scaled values exceed 255, the maximum grayscale image quantizationvalue so you may want to decrease the scale factor a bit. As long as you use thesame scale factor between images, the TOA reflectance values can still be validsince they are scaled absolute numbers. If you decide to create such images,you can output them in any of the standard PANCROMA TM output formats. ATOA reflectance image, with scaleFactor=500 is shown below.Landsat 7 Top of Atmosphere RadiancePANCROMA TM can compute TOA radiance in a fashion similar to TOAreflectance. TOA radiance is given by:Lλ = Grescale * QCAL + Brescale183