User Manual - pancroma

Note that the TOA Reflectance Data Form contains a check box marked ‘Write 8-Bit GeoTiff File. If this box is checked, PANCROMA TM will write the EuclideanDistance or Spectral Angle values to a GeoTiff file. The values will be scaledbetween 0-255 so that they can be viewed in other applications. Note that thedarker the grayscale pixel value, the smaller the Euclidean Distance, so targetareas will appear black.After a bit of computation, two images will become visible, a grayscale image andan RGB contour image. The grayscale image displays the Euclidean Distances,scaled to fall between 0 and 255. The RGB contour plot plots the actualEuclidean Distances with red being the shortest distance and violet being thegreatest. Note that in the grayscale plot, black represents the closest match andpure white (DN=255) is the farthest distance. If you are running two spectra, theSpectral Criteria Form will appear a second time. This time enter the secondspectrum.The analysis shown below uses the Euclidean distance method, running thesnow pack example with two input spectra. I generated target vectors using thePoint Spectrum Generator TM . After clicking on the targets in each image andselecting a dozen or so points, I checked the ‘Enter Spectrum into Analyzer’check box. In addition to generating my spectrum, it automatically entered thefirst set of average reflectance values into the Spectral Criteria Form. (Thesecond set has to be entered manually).The following image shows the first Euclidean Distance plot. The bright redareas correspond to the minimum Euclidean Distance and therefore the bestmatch with the target vector. The purple areas are the worst matches, i.e. thefarthest Euclidean Distances. The red areas correspond to the obvious snowareas in the band images, with the orange and yellow areas being probablematches as well in this case. Note that you can turn off the color scale byunchecking the ‘Display Euclidean Distance Scale’ check box on the SpectralCriteria form.251