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1/9 flt files over 4 gigs

redbeardredbeard Global Mapper UserPosts: 279Trusted User
edited September 2010 in Bug Report
I'm having trouble opening some of the 1/9 NED files I have - namely the ones over 4 Gigs. They are in gridfloat format (.flt). There are hdr and prj files in the directory.

They....turn out looking like a barcode. Using either the latest version 11 or beta 12. These are files directly from the USGS bulk data service.

If I try to add those files to a new catalog - (via add directory) it skips those files. The drive is formatted as ntfs - though the USGS returned the external HD formatted as fat32(?). But the files were there - 30 of them 4 gigs and up.

Arcmap seems to be able to read them (using the arctoolbox float to raster in order to get them in arcmap as it doesnt directly support flt files).

(my testing is done on the smallest >4gig file)

Any ideas?


  • redbeardredbeard Global Mapper User Posts: 279Trusted User
    edited September 2010
    Well, I exported the file from Arcmap as a erdas .img file with no compression, (~4.5 gigs) and Global Mapper opens that.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited September 2010
    I created a 9GB Float/Grid to test and was able to find the issue and fix it. I have placed a new build at with the change for you to try. Simply download that file and extract the contents into your existing v12.xx installation folder to give it a try. If you are using the 64-bit v12 version there is a new build at .

    Let me know if I can be of further assistance.


    Global Mapper Support
  • redbeardredbeard Global Mapper User Posts: 279Trusted User
    edited September 2010
    Seems to have loaded the smaller (test) of the files - Thanks!
  • tjhbtjhb Global Mapper User Posts: 454Trusted User
    edited September 2010
    I have had a similar problem in the past, where after writing a a large .flt grid GM could not read it back in (though Manifold could read it fine). Thanks to redbeard for reporting it and to Mike for fixing it.
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