Global Mapper Pro

Combine file size guidance

ShermJensen@sisna.com
ShermJensen@sisna.com Global Mapper UserTrusted User
edited December 2009 in Elevation Data
Hi Mike: I am combining GMGs from LiDAR to get vegetation canopy height. My canopy layer is 1ft resolution and my bare earth is 1m. I keep running into "out of memory" errors when I try to combine at 1 ft resolution, even when I grid the 24,000 acres to 5X6, 8X8, and 10X12. I seem to run into the error in the same area, even when I seriously reduce the extent. (I did not see any difference when I combined the gridded 1 ft canopy with the ungridded 1m vs gridded 1 ft and 1m).

I want to make a fresh run at this with whatever size grid I need to avoid exceeding my memory (3.34 GB). Can I determine if combine will work based on the grid file size?

Thanks

Comments

  • global_mapper
    global_mapper Administrator
    edited December 2009
    What version of Global Mapper are you using? Also, to really avoid memory constraints you need to either use the 64-bit version or check the option to create Global Mapper Grid files rather than creating the grids in memory.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • ShermJensen@sisna.com
    ShermJensen@sisna.com Global Mapper User Trusted User
    edited December 2009
    Version 10.02 -- is this a 64 bit version? My inputs are tiled Global Mapper Grids (10-130 MB) of top of canopy (TOC) and a single GMG representing bare earth(169 MB). I subtract (unsigned) the bare earth GMG from a single TOC grid to combined terrain (decifeet) with 1 ft X 1 ft sample spacing. The combined terrain is loaded on the overlay control center. I see from the metadata that these combined terrains have a description, but no file name. So are they only in memory? I don't see the option to create Global Mapper Grid files rather than creating the grids in memory. Do I need version 11?

    Thanks
    Sherm
  • redbeard
    redbeard Global Mapper User Trusted User
    edited December 2009
    64-bits came with version 11.
  • global_mapper
    global_mapper Administrator
    edited December 2009
    The option to directly create Global Mapper Grid files when creating elevation grids was added in v9.03, but it is for when you are creating grids from vector layers, not when combining terrain layers in memory to create new ones. When you use the File->Combine Terrains menu command it does create the combined grid in memory, so if your combined grid is huge it could use all of your memory. The 64-bit v11 would help increase the size that you can combine at once, assuming of course that you have 64-bit Windows and significant memory.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • ShermJensen@sisna.com
    ShermJensen@sisna.com Global Mapper User Trusted User
    edited December 2009
    Thanks Mike. That solved my problem. I did three tiles, dumped to GMG, deleted the combined files, then started on the next three. It's amazing what a little understanding can do. Great council!:)
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