How do you duplicate a layer?

Can someone please explain how to duplicate a layer? Say for example an elevation grid or vector layer.

Thank you.
Steve

Comments

  • MykleMykle Global Mapper User Posts: 358Trusted User
    Using my usual workflow, layers are saved to local files.  A duplicate layer can be created by loading appropriate files.  This is especially useful for data downloaded from the internet, since loading local files is much faster than downloading (again) internet data. 

    This works for raster and elevation data.  However if you are saving internet raster data, pay attention to the resolution that is specified during export.  The default is likely to be the maximum resolution of the internet data, and that may be much too detailed for your purposes.  Also, different data may be displayed at different resolutions, so your choice of export resolution will determine what your file includes. 

    USA Topo Maps, for example, includes data at scales of 1:250K, 1:100K, and 1:24K that change with the zoom level you select.  Export resolution is separate: if you specify a resolution of 18m, you will get 100K.  Higher resolutions will give you 24K.  I'd like to be able to specify a zoom level to be saved at a higher resolution, but you will need to find and load separate map files for more flexibility. 

    In general, you cannot select a raster layer, then paste it.  In many cases you CAN select vector features and copy them elsewhere.  Remember to check any attributes that may be associated with your data to ensure that they were also copied. 

    I would like to be able to save vector data to a file that would import with all attributes, and Mike has recommended using the Shapefile format.  However, I have not had the best results from this method and don't know of another suitable format. 
  • Thanks for your response. I take it that it is not possible to copy and paste layers or simple elevation grids created in GM. Maybe this would make for a useful suggestion for future releases. Seems to be a basic feature in many CAD/GIS applications that would be great in GM.
  • MykleMykle Global Mapper User Posts: 358Trusted User
    Global Mapper gives you more than enough flexibility to make layers very complicated, with data loaded from a variety of sources, local and remote, and perhaps heavily edited.  Data formats may use different datums (data) and projections.  Copy-and-paste could become very difficult. 

    I find it easier and more productive to load data, change the display, modify data, then export to local files.  The data are more easily documented and used for other purposes.  As a result, the program is faster and tracking down problems is easier.  One of my jobs is to make others (co-workers and clients) more productive.  The old saying is very true: "Keep it simple". 

  • In ArcGIS it is very easy to copy and paste layers that face the same problems you mention e.g. datums/projections, so at least in theory it could be a feature that could be added.
  • bmg_bobbmg_bob Global Mapper Programmer Posts: 1,646
    sphillips said:
    In ArcGIS it is very easy to copy and paste layers that face the same problems you mention e.g. datums/projections, so at least in theory it could be a feature that could be added.
    For vector, data, you can use the Digitizer to select all (or a subset) of features in a layer, then copy and paste them.  During the paste operation, you will be prompted to choose a destination layer or create a new one.

    There is currently no way to duplicate a raster or elevation grid layer, other than using the suggestion from @Mykle
    above to export a new file and then import it.

    Cheers,
    Bob


  • sphillipssphillips Posts: 38
    Thank you Bob - much appreciated.
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