User Manual - pancroma

The Tasseled Cap transformation can be computed from band file digitalnumbers (DNs) or more correctly using Top of Atmosphere reflectance, which isthe default condition. If you compute using reflectance values, you must obtainthe Solar Elevation Angle and the Acquisition Date from the Landsat metadatafiles as described in the section above entitled ‘Landsat Top of AtmosphereReflectance’. If you wish to use DNs, check the ‘Compute using DNs’ radiobutton.The ‘Render Color Image’ check box is also true by default. If you wish you canindividually select the ‘Write Float’ check boxes. Checking these will causePANCROMA TM to write the raw Tasseled Cap values to disk file. You can outputone, two, all three, or none of these files. Be advised that each one contains fourtimes the bytes of the input band files as the values are 32 bits each rather than8 like the input band files.After processing, a composite color image will be displayed rendering theTasseled Cap transformation. You can save this file to disk as usual byselecting ‘File’ | ‘Save RGB Image’. An example of such an image is shownbelow.201