User Manual - pancroma

Another difference is file format. The most recent SPOT data is archived inDIMAP format, which is SPOT Imaging Corporation’s designation for GeoTiff 1.0.Orthorectified SPOT images obtained from Canada’s GeoBase repository arealso formatted in GeoTiff, although the source or raw imagery is archived in theolder CAP format. At this time PANCROMA TM is not capable of reading CAPalthough it can read all of the SPOT GeoTiff data just like Landsat. SPOTimages are also available from the USGS Earth Explorer website. These imagesare archived in false color RGB format. However SPOT bands 1, 2 and 3 can beextracted by decomposing these files using a PANCROMA TM utility. Onceextracted and saved, the band file can be used exactly as those downloadeddirectly from the GeoBase website. To extract the band files from SPOT data seethe section on decomposing SPOT data below.Creating SPOT Band File ImagesIn order to combine SPOT band images directly, process the data exactly asdescribed in the ‘Processing Data - RGB True Color Image’ section in thismanual. That is, Select ‘File’ | ‘Open’. Select your desired file type (SPOT is notarchived in .jpeg or .L1G format). Successively select and open the desiredbands. GeoBase SPOT files will have the suffix have … m20_1_utm10.tif’, …m20_2_utm10.tif’, … m20_3_utm10.tif’, … m20_4_utm10.tif’. A full file name inthe UTM coordinate system will look like‘S4_11930_5531_20060629_m20_4_utm10.tif’. As you add the files, theirnames will be echoed on the diagnostics/dialog box.Once all three files are opened, the appropriate menu selections and checkboxes will be activated on the main screen as before. Select ‘Display Files’ |Generate RGB Composite’IMPORTANT NOTE: The ‘Generate RGB Composite’ will produce true colorimages when Landsat data is input and false color images when SPOT band filesare input. This menu selection would be better named ‘Direct BandCombination’.After the file is processed, the image will be displayed and you can save it to diskas described previously.Creating SPOT Natural Color ImagesAlthough SPOT band files are very useful, you may need SPOT images thathave more natural color, for example for overlaying to create terrain models. Toobtain such images, open SPOT bands 1, 2 and 3 in order as usual. Then select‘Display Files | Generate RGB True Color Composite from SPOT’. This menuselection invokes an algorithm that processes the band data to produce morenatural looking images. See Section 47 in this manual for instructions for using93