User Manual - pancroma

'Enter' and the Adjust file will be subsetted to the same latitude and longitudecoordinates as the Reference subset images that you previously created. Inamed my subsetted files 'Reference' and 'Adjust'. (Band identification suffixesare automatically attached. The band1 Reference and Adjust images are shownon the right.The Reference and Adjust subset images should be exactly the same size if youhave matched the resolutions. It is necessary for the images to not only havecorresponding latitude and longitude corner coordinates, but they must have thesame number of pixels as well. PANCROMA TM has a utility for resizing images ifthey do not match. The resize utility uses a simple x and y scaling algorithm toachieve the fit. In general it is more accurate to co-register both images usingcontrol points but since the images will be nearly the same size after subsettingthe scaling approach will yield the same result for matching the images to eachother.PANCROMA TM will decrease the size of the larger image to match the smallerone. As a result it is necessary for you to load the larger set by opening the threeband files. Then select 'Band Combination' | 'Subset Images' | 'Resize Images'.The three images will appear on the screen along with the 'Resize Data InputForm'. Enter the row and column values for the smaller set into the text boxesand select 'OK'. The images will be scaled down. You can save the resizedimages when the process is complete.At the end of this operation, you should have six processed Landsat band files:two blue, green and red band files for the Reference image and two blue, greenand red files for the Adjust image, all the same size and with the same cornercoordinate in the same projection to the same datum. One set will have gapsand the other will be whole. You are now ready to gap fill and process theimages using PANCROMA TM .The process is fairly straightforward. The six band files are loaded in pairs: firstthe two blue bands, then the two green bands, and finally the two red bands, inthe order: Reference band (with gaps) then Adjust band (without gaps). Eachpair is gap filled immediately after loading by selecting ‘Gap Fill’|’ETM+ Gap Fill’from the menu. Each gap-filled grayscale image must be successively saved,and then the next pair is loaded, repeating the process. PANCROMA TM uses thenon-linear histogram matching algorithm to automatically modify the ‘Adjust’image in order to get a close match to the ‘Reference’ image. Without thehistogram match, the radiance differences between the Reference and Adjustimages would result in a severely striped image in most cases.My example gap filled images are shown below. There is some faint stripingvisible but much of this is due to seasonal differences in vegetative covering.Both these image pairs show the benefit of gap filling and the satisfactory resultsthat can be achieved.324