[ncl-talk] How to convert a contour map to a raster file from a nc file?

[Dennis Shea]

re: "my nc file is just known by the remote server I work at. After copying
the file to my desktop, and opening it by Panoply , it is no longer valid
as a nc file"

This is  "no longer valid as a nc file" does not make sense to me. Are you
sure it was netCDF [eg: .nc, .nc4, ... extension]









On Wed, Jun 10, 2020 at 10:45 AM zoe jacobs via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:

> Dear Dave,
> Many thanks for your explanations. My problem is that my nc file is just
> known by the remote server I work at. After copying the file to my desktop,
> and opening it by Panoply , it is no longer valid as a nc file ! . So I
> look for a way to sort it out. What can I do please?
> Many thanks in advance,
> Best wishes,
>
> On Tue, Jun 9, 2020 at 10:19 PM Dave Allured - NOAA Affiliate <
> dave.allured at noaa.gov> wrote:
>
>> According to this article, your original Netcdf file is already in a GIS
>> raster format.
>>
>>     https://en.wikipedia.org/wiki/GIS_file_formats
>>
>> You should be able to skip the plotting step, and use the Netcdf file
>> directly in ArcGIS.  Minor adjustments may be needed for coordinates and
>> area subsetting.  My guess is that this is really what you want to do.
>>
>> The expression "raster format" is problematical because it is used for at
>> least three fundamentally different things in computer graphics.
>> Generically, this refers to common "bit-mapped" image file formats such as
>> png, gif, and jpeg.  In GIS and satellite imagery, it refers to a variety
>> of gridded data formats, including Netcdf.  And NCL has a specialized
>> usage, referring to the rendering of gridded data as visibly rectangular
>> blocks when making plots, rather than smooth or segmented outlines.  It
>> would be nice if these nuances of terminology were discussed in NCL
>> documentation, but, um, they are not.
>>
>> To make things more confusing, some of these formats can be "rendered" in
>> one of the other formats, often losing software compatibility in the
>> process.  The picture on your example raster_4.ncl is a perfect example of
>> this.  That is an NCL "raster plot" projected onto a PNG "raster format"
>> image file for website display.  The "pixels" before and after are
>> completely different.  So be careful about which usage you are discussing.
>>
>>
>> On Tue, Jun 9, 2020 at 10:06 AM zoe jacobs via ncl-talk <
>> ncl-talk at mailman.ucar.edu> wrote:
>>
>>> Dear all NCL users,
>>>
>>> I would like to create a map plot in raster format from a nc file . So I
>>> can then use it on ArcGIS. Please have a look at the following link
>>> https://www.ncl.ucar.edu/Applications/raster.shtml , example
>>> easter_4.ncl . I already could plot a contour map from my nc file, and
>>> I just wonder which command should I add to my script to convert my plot to
>>> be in a raster format?
>>> Would you please kindly advise me in this regard?
>>> Best wishes,
>>>
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