User Manual - pancroma

http://www.science.aster.ersdac.or.jp/en/documnts/users_guide/index.html. Atthe bottom of the screen is a check box that lets you lock all the sliders andanother check box that allows you to save your settings between runs. Note thatI have input the selection criteria from my channel plot.When you click ‘OK’, the TOA Reflectance Data Form will appear. This containsthe usual reflectance computation criteria. Since the spectra are given asreflectances, the band digital numbers (DNs) must be converted. This will bedone in the same way as described in Section 49 Landsat Top of AtmosphereReflectance. Make sure that the ‘Render Color Image’ check box is checked(this is the default). When you click “OK’, the LSA will convert the DNs to TOAreflectances. It will report the maximum and minimum reflectance values to theMain Window data screen. Note that some reflectance values may be less thanzero. This of course does not make sense. PANCROMA TM uses the methodproscribed in the Landsat Data Users Handbook directly without biasing thecomputed values to make them all positive or zero. Since the magnitude of anynegative reflectances is usually very small, this is not a problem.PANCROMA TM will mark each pixel that matches the comparison criteria bycoloring it red, and displaying it on the band1 grayscale image. The results of myfirst run were exactly... nothing. No hits at all. I inspected the maximumreflectance value for the band4 channel and noticed that it was around 0.8. Iconcluded that there might be a standard error between the measuredreflectances and the spectrum. I made a second run decreasing all channelvalues by 0.2 units and again got no hits. I then decreased all channels byanother 0.1 unit. This yielded the image shown below. (The image is shown athalf scale so that it fits on the page conveniently.)Comparison of the marked plots with the RGB image shown that the scan hasapparently marked the plowed fields, not the lawn grass. I “ground truthed” theimage using a high resolution aerial photograph and this seemed to confirm mysuspicion. I also included a band 145 false color composite, commonly used todiscriminate vegetation for comparison. (Note that PANCROMA TM will computethe percentage of red pixels on the active part of the image and display them inthe Main Window dialog box.)240