Global Mapper v25.0

Opening and Cropping huges files

criquet
criquet Global Mapper UserTrusted User
edited January 2010 in Technical Support
Hi,

Is it possible to open files in GM11 cropped into selected area feature in order to open big big files faster (same as the export option) ?
If it is not possible, is there any way to avoid opening entire files (i.e. entire world) only for a specific area ?

Thank you for your answer, and sorry for my average level in english :confused: !

Criquet

Comments

  • global_mapper
    global_mapper Administrator
    edited January 2010
    Criquet,

    There is not currently a way to load just a portion of a file, although you can crop raster files after loading using the Cropping tab of the Options dialog for that layer. In general for raster or elevation files that are read from disk on the fly anyway, cropping the layer won't really speed things up at all anyway.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • STH
    STH Global Mapper User Trusted User
    edited January 2010
    criquet: which format is the original file/files in? (ie are all files *.tif *.jpg *.ecw or other?)
  • criquet
    criquet Global Mapper User Trusted User
    edited January 2010
    Thank you for your prompt answers.

    What I would like to load faster is the continuous terrain model for entire world ocean and land "Gebco Bathymetric grid" (resolution of 30 arc-seconds). This file is a 1,8Go .NC file (NetCDF??).
    What I would like to do, is to load only a regional area, that is to cropp the file within a specific selected area.

    But unfortunatly, Mike says that is not possible, and won't really speed things up.

    STH, would you have a special trick ?
  • global_mapper
    global_mapper Administrator
    edited January 2010
    The slow load in this case is primarily due to the format that the data is in. What I would do is convert the file to a Global Mapper Grid file, then load that in the future. The file will not only be much smaller but will also load and display extremely fast.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • criquet
    criquet Global Mapper User Trusted User
    edited January 2010
    Hi,

    Thank you Mike for your advice ! I 'm going to try it right now
  • STH
    STH Global Mapper User Trusted User
    edited January 2010
    Sorry, no further advice since it is on the NetCDF-format other than GlobalMappers suggestion
  • criquet
    criquet Global Mapper User Trusted User
    edited January 2010
    I've created the Global Mapper grid from the nc grid.
    Result of the test : it's now a 662 Mo file and I can open it in less than 1 second on my computer (instead of more than 15 minutes before) !
    Thank you again for the tip

    Criquet