Global Mapper Pro

Exporting GeoTiff - File Size and Export Time

KADguy Global Mapper User
edited November 2010 in Raster Data
Hi - I'm working on an energy related project that crosses three counties. I've downloaded the 2006 NAIP aerial imagery for each county and opened each of them in GM in order to change the coordinate system, remove collars and merge them into one file. The size of the files when downloaded is 733mb, 550mb and 115mb. What I'm having problems with is the time (GM is projecting 18 hours) it is taking to export the GeoTiff and the file size (2.3gb - I did a test run yesterday evening before removing the collars) associated with the export. The project does not encompass every square inch of all three counties so I have "drawn a box" in the export bounds tab in hopes to minimize the time and size... but that doesn't help.

On the GeoTiff Export Options tab I've selected 8-bit palette image as file type, Image Optimized Palette as Palette type, selected to Always generate square pixels, and checked all three boxes to Interpolate to fill small gaps in data, generate TFW (World) File, and generate PRJ File. On the Gridding Tab, I've selected No Grid - Just one export file. And as mentioned earlier, I've drawn a box to select the area in the imagery that I'm interested in exporting.

Do you have any suggestions on how to minimize the export time and file size associated with the GeoTiff?

Thanks a bunch.


  • global_mapper
    global_mapper Administrator
    edited November 2010
    I would uncheck the box to 'Interpolate to Fill Small Gaps' as you really shouldn't need it in this case and it could slow things down a bit. Other than that using an image-optimized palette will also nearly double the export time for input imagery like this and also isn't a good choice for imagery. I would suggest instead using the 24-bit RGB GeoTIFF export with JPEG-in-TIFF compression.

    Let me know if I can be of further assistance.


    Global Mapper Support
  • KADguy
    KADguy Global Mapper User
    edited November 2010
    Mike - Many thanks. That worked.
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