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Hi Ken,<br>
I see. This way you will have to resample your data into the other
coordinate system tho. That might indeed be a bit tricky with a
Polar projection.<br>
Hit me up if you need any info on the workaround.<br>
Michel<br>
<br>
<div class="moz-cite-prefix">On 17.08.2017 23:11, Ken Mankoff wrote:<br>
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<blockquote type="cite"
cite="mid:CAFdBzEqMbZy98dOH2yVxRYLjZ5UqM_+iQC6i=Whitrz5GmybfQ@mail.gmail.com">
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monospace" color="#484848">
<div><span style="font-size:12px">Hi Michel, list,</span></div>
<div><span style="font-size:12px"><br>
</span></div>
<div><span style="font-size:12px">I've come across a
different method - using the CDO tools to remap the
rotated pole data set.</span></div>
<div><span style="font-size:12px"><br>
</span></div>
<div><span style="font-size:12px">See thread here: <a
href="https://code.mpimet.mpg.de/boards/2/topics/96"
moz-do-not-send="true">https://code.mpimet.mpg.de/boards/2/topics/96</a></span></div>
<div><span style="font-size:12px">The answer there uses a
simple ASCII "mygrid" as the target grid, but the
command can be "cdo remapbil,<a href="http://file.nc"
moz-do-not-send="true">file.nc</a> ifile ofile" where
"<a href="http://file.nc" moz-do-not-send="true">file.nc</a>"
is a netcdf file that represents the target grid. It has
specific format requirements discussed here: <a
href="https://earthscience.stackexchange.com/questions/8086/interpolate-gaussian-grids-to-regular-fixed-grids-using-bilinear-interpolation"
moz-do-not-send="true">https://earthscience.stackexchange.com/questions/8086/interpolate-gaussian-grids-to-regular-fixed-grids-using-bilinear-interpolation</a></span></div>
<div><span style="font-size:12px"><br>
</span></div>
<div><span style="font-size:12px">I'm trying to figure out
this CDO method, and having trouble converting my GRASS
GIS projection information (and the longitude and
latitude coordinates for each grid cell) to the correct
NetCDF file... work is in progress.</span></div>
<div><span style="font-size:12px"><br>
</span></div>
<div><span style="font-size:12px">If I can't do it this way
I'll hand-code it as you suggested in your reply. I'm
not totally clear on your method yet, so I may write and
ask for more details.</span></div>
<div><span style="font-size:12px"><br>
</span></div>
<div><span style="font-size:12px">Thanks,</span></div>
<div><br>
</div>
<div> -k.</div>
<div style="font-size:12px"><br>
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<div class="gmail_extra"><br>
<div class="gmail_quote">On Thu, Aug 17, 2017 at 12:49 PM,
Michel Wortmann <span dir="ltr"><<a
href="mailto:wortmann@pik-potsdam.de" target="_blank"
moz-do-not-send="true">wortmann@pik-potsdam.de</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div bgcolor="#FFFFFF"> Hi Ken,<br>
I have had to compare lonlat data with ncdf rotated pole
data before and also chose to import the centroids of
the rotated grid into a vector. To fill the cells I
actually converted the points to much smaller resolution
(e.g. you could use the 30m of your other dataset)
raster cells with an ID and used r.grow.distance to
create an ID grid. I could then just reclass this ID
grid for each timestep, meaning no excess data in the
grass db. At the time it seemed like a bit of a
workaround, but reading the thread below makes me think
this is the way to go.<br>
<br>
Regards,<br>
Michel
<div>
<div class="gmail-h5"><br>
<br>
<br>
<br>
<div
class="gmail-m_-5692177127320398116moz-cite-prefix">On
15.08.2017 14:38, Ken Mankoff wrote:<br>
</div>
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<blockquote type="cite">
<div>
<div class="gmail-h5">
<div dir="ltr">It seems that my suggested approach
might be the right one based on this thread from
2012: <a
href="https://lists.osgeo.org/pipermail/grass-dev/2012-March/058179.html"
target="_blank" moz-do-not-send="true">https://lists.osgeo.org/<wbr>pipermail/grass-dev/2012-<wbr>March/058179.html</a>
<div><br>
</div>
<div> -k.</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Tue, Aug 15, 2017 at
1:59 PM, Ken Mankoff <span dir="ltr"><<a
href="mailto:mankoff@gmail.com"
target="_blank" moz-do-not-send="true">mankoff@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">Hi GRASS
list,<br>
<br>
I'm trying to compare two data sets and need
to import them into the same location. One
is a GeoTIFF in WGS84 lon,lat coordinates.
When I create a new GRASS location using "-c
file.tif" everything appears to work, and<br>
<br>
$ g.region -p<br>
projection: 99 (unnamed)<br>
zone: 0<br>
datum: wgs84<br>
ellipsoid: wgs84<br>
etc...<br>
<br>
And from gdalinfo:<br>
<br>
Coordinate System is:<br>
PROJCS["unnamed",<br>
GEOGCS["WGS 84",<br>
DATUM["WGS_1984",<br>
SPHEROID["WGS
84",6378137,298.257223563,<br>
AUTHORITY["EPSG","7030"]],<br>
AUTHORITY["EPSG","6326"]],<br>
PRIMEM["Greenwich",0],<br>
UNIT["degree",0.01745329251994<wbr>33],<br>
AUTHORITY["EPSG","4326"]],<br>
PROJECTION["Polar_Stereographi<wbr>c"],<br>
PARAMETER["latitude_of_origin"<wbr>,70],<br>
PARAMETER["central_meridian",-<wbr>45],<br>
PARAMETER["scale_factor",1],<br>
PARAMETER["false_easting",1],<br>
PARAMETER["false_northing",1],<br>
UNIT["metre",1,<br>
AUTHORITY["EPSG","9001"]]]<br>
Origin = (107900.000000000000000,-65555<wbr>0.000000000000000)<br>
Pixel Size = (30.000000000000000,-30.000000<wbr>000000000)<br>
<br>
<br>
I have a second data set that I would like
to co-locate with this one. That data comes
in a NetCDF file but the projection is a
custom rotated-pole projection. I have three
variables in the NetCDF file: lon, lat, and
the data.<br>
<br>
What is the best method to convert on data
set to the other? My first approach might be
to convert the NetCDF to lon,lat,data ASCII
file, import as points with m.proj, then
convert to raster. I'm wondering if this is
what the experts on this list would do. Note
that I have one TIF, and 50,000 NetCDF time
steps, so it may be more efficient to
convert the TIF to the custom NetCDF
projection, but it is not a requirement.<br>
<br>
Thanks for any advice you may have,<br>
<br>
-k.<br>
<br>
<br>
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