User Manual - pancroma

ALI data is similar to Landsat with a few differences. The first major difference isthe dynamic range of the ALI data: 16 bits versus 8 bits for Landsat. In order tobe displayed as an image by standard desktop computing equipment, the 16 bitdata must be scaled to accommodate an 8-bit grayscale or RGB color model.PANCROMA TM handles this the same way it handles 11 bit Digital Globe data,by scaling by a ratio of 255/MAX_VALUE where MAX_VALUE is the largest DNvalue in the image.Alternatively every DN can be divided by successive multiples of two (bit shift).The former is the PANCROMA TM default while the latter can be accomplished bychecking the ‘Bit Shift Enable’ check box on the PANCROMA TM ImageProcessing Data Input screen. In either case, after extracting all of the band filesfrom the .tar.gz file, each band must be loaded (‘File’ | ‘Open’ | ‘Display Files’ |‘Display Single Grayscale Image’), scaled (‘Activate Image Processing Routines’check box or alternatively accept default method), and then saved to disk afterscaling.The second difference is the number and arrangement of the band files. Landsathas 8 30m multispectral bands plus a 15m panchromatic band. ALI has 9 30mmultispectral bands plus a 10m panchromatic band. As a result, bands 3, 4 and5 correspond to Landsat bands 1, 2 and 3 while ALI band 1 (panchromatic)corresponds to Landsat band 8.The ALI multispectral bands are not even multiples of the panchromatic band.As a result, all of the band files (both multispectral and panchromatic) must bedecreased by exactly one row and one column. You can accomplish this usingthe PANCROMA TM ‘Pre Process’ | ‘Rescale‘ | ‘Rescale Three Images’ and ‘PreProcess’ | ‘Rescale‘ | ‘Rescale Single Image’ selections.After resizing, you can pan sharpen the multispectal band files as usual. Sincethe panchromatic band is three times the resolution of the multispectral bands,the Laplacian interpolation will be the default and it will be necessary to use theappropriate number of iterations (at least 40) to process the hue and saturationimages. Note that since the panchromatic band spectral range exactly matchesthe combined range of the RGB bands, NIR processing techniques such asXIONG and ENHG are not generally helpful.IMPORTANT NOTE: EO-1 files must be individually converted from 16-bit to 8-bit format before subsequent processing. It is not possible to open multiple EO-1files and directly create a RGB color composite, for example.IMPORTANT NOTE: The simple nearest neighbor interpolation that is thedefault for Landsat processing will not work for the 3:1 size ration of EO-1 ALI.Laplacian interpolation is the default with 40 iterations. If you wish to increase ordecrease the iterations you should check the ‘Activate Image ProcessingRoutines’ and modify the ‘Interpolation Method’ data entry panel.102