Changes between Version 5 and Version 6 of FAQ

Jun 29, 2009 5:01:41 PM (10 years ago)

Added processing speed/file size answer


  • FAQ

    v5 v6  
    2323This would produce two geocorrected images, each with one part of the line.
     26'''Q:''' Is there any way to speed up geocorrecting my data or to reduce the file size of the geocorrected files?
     29There are three main ways to do this:
     311. Only geocorrect bands you want to look at. Azgcorr can be passed a -bl parameter that tells it only to geocorrect bands in the given list. For example, to correct bands 4, 5 and 6 you'd use:
     33azgcorr ... -bl 4 5 6 -1 ...
     35...the -1 at the end is necessary to tell azgcorr that you've finished giving it band numbers.
     372. If you're only interested in part of the flightline, don't process the parts you're not interested in. This may require some trial-and-error to establish the line numbers. Use the -l option to azgcorr to process only a certain range of scan lines. You'll need to run the whole thing through once, optionally with only one band as above, to check the total number of scan lines. For example, for a flightline with 10000 scan lines, if you only want lines 2000-6000 you'd use:
     39azgcorr ... -l 2000 6000 ...
     413. Make the pixel size you're using larger - larger pixels give less detail, but the file size is inversely proportional to the square of the pixel size, so if you double the pixel size (if you don't need the extra detail) you will reduce file sizes by roughly 75%.