<div><div dir="auto">Has anyone looked into the so called regrid in Earth system model? How is it different from GIS resampling?</div></div><div dir="auto"><br></div><div dir="auto"><h3 style="margin:0px 0px 1em;padding:0px;border:0px;font-size:16px;font-family:Arial,sans-serif;vertical-align:baseline;line-height:1;color:rgb(102,102,102)">Grid Remapping</h3><p style="margin:0px 0px 1.5em;padding:0px;border:0px;font-size:12px;font-family:Arial,sans-serif;vertical-align:baseline;color:rgb(51,51,51)"><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-family:Arial,sans-serif;vertical-align:baseline">ESMF has the option to build a standalone application, called </span><strong style="font-family:Arial,sans-serif"><a href="http://www.earthsystemcog.org/projects/regridweightgen" style="margin:0px;padding:0px;border:0px;font-weight:inherit;font-style:inherit;font-size:19px;font-family:Arial,sans-serif;vertical-align:baseline;text-decoration:none;color:rgb(53,140,146)">RegridWeightGen</a></strong><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-family:Arial,sans-serif;vertical-align:baseline">, that can generate interpolation weights in parallel. It's fast and can handle a wide variety of grids and grid options. It's not necessary to use the rest of ESMF to use it ... just provide grid files in a standard (netCDF-based) format.</span></p><p style="margin:0px 0px 1.5em;padding:0px;border:0px;font-size:12px;font-family:Arial,sans-serif;vertical-align:baseline;color:rgb(51,51,51)"><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-family:Arial,sans-serif;vertical-align:baseline"><div style="font-family:Arial,sans-serif"><a href="https://www.earthsystemcog.org/projects/esmf/">https://www.earthsystemcog.org/projects/esmf/</a></div><br></span></p><p style="margin:0px 0px 1.5em;padding:0px;border:0px;font-size:12px;font-family:Arial,sans-serif;vertical-align:baseline;color:rgb(51,51,51)"><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-family:Arial,sans-serif;vertical-align:baseline">Thanks.</span></p><p style="margin:0px 0px 1.5em;padding:0px;border:0px;font-size:12px;font-family:Arial,sans-serif;vertical-align:baseline;color:rgb(51,51,51)"><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-family:Arial,sans-serif;vertical-align:baseline"><br></span></p></div><div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Aug 20, 2020 at 8:40 AM Stephen Woodbridge <<a href="mailto:stephenwoodbridge37@gmail.com">stephenwoodbridge37@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)">Jukka,<br><br><br><br>Thanks those are great threads and very educational.<br><br>I solved my problem. I was using upsample="bilinear" rather than <br><br>upsampling="bilinear" and fixing this gave the expected results. But if <br><br>not for my stupid typo, I would not have had a chance to read those <br><br>threads and google others regarding upsampling.<br><br><br><br>Thanks for the assist,<br><br>-Steve<br><br><br><br>On 8/20/2020 10:13 AM, Rahkonen Jukka (MML) wrote:<br><br>> Hi,<br><br>><br><br>> Resampling is science that would be nice to understand. Unfortunately I don't but I think that this thread is worth reading <a href="http://osgeo-org.1560.x6.nabble.com/gdal-dev-downsampling-geotiff-with-a-low-pass-filter-td5385890.html" rel="noreferrer" target="_blank">osgeo-org.1560.x6.nabble.com/gdal-dev-downsampling-geotiff-with-a-low-pass-filter-td5385890.html</a>. In this gis.SE question cubic spline was considered good <a href="https://gis.stackexchange.com/questions/30627/smoothing-reinterpolating-raster-with-gdal" rel="noreferrer" target="_blank">https://gis.stackexchange.com/questions/30627/smoothing-reinterpolating-raster-with-gdal</a>.<br><br>><br><br>> -Jukka-<br><br>><br><br>> -----Alkuperäinen viesti-----<br><br>> Lähettäjä: Stephen Woodbridge <<a href="mailto:stephenwoodbridge37@gmail.com" target="_blank">stephenwoodbridge37@gmail.com</a>><br><br>> Lähetetty: torstai 20. elokuuta 2020 16.58<br><br>> Vastaanottaja: Rahkonen Jukka (MML) <<a href="mailto:jukka.rahkonen@maanmittauslaitos.fi" target="_blank">jukka.rahkonen@maanmittauslaitos.fi</a>><br><br>> Aihe: Re: [gdal-dev] I have a problem getting higher resolution in a VRT file<br><br>><br><br>> Hi Jukka,<br><br>><br><br>> Any thoughts on what would be a better way to upsample and image using GDAL?<br><br>><br><br>> I assumed, maybe incorrectly, that if I’m up sampling between two pixels with values of say 1 and 2 that a new pixel 50% between them would get a value of 1.5 and at 25% would get a value 1.25 etc. using linear interpolation and bilinear would also account for rows above and below the current row.<br><br>><br><br>> Even, I specified resampling=“bilinear” in the vrt file is this ignored?<br><br>><br><br>> Thanks, Steve<br><br>><br><br>> Sent from my iPhone<br><br>><br><br>>> On Aug 20, 2020, at 8:23 AM, jratike80 <<a href="mailto:jukka.rahkonen@maanmittauslaitos.fi" target="_blank">jukka.rahkonen@maanmittauslaitos.fi</a>> wrote:<br><br>>><br><br>>> Even Rouault-2 wrote<br><br>>>> ...<br><br>>>> By default, VRT uses nearest resampling. You must specify something else.<br><br>>>> Look for "A resampling attribute can be specified" in<br><br>>>> <a href="https://gdal.org/drivers/raster/vrt.html" rel="noreferrer" target="_blank">https://gdal.org/drivers/raster/vrt.html</a><br><br>>>> ...<br><br>>>><br><br>>>> --<br><br>>> Actually in the provided .vrt file I can see <SimpleSource<br><br>>> resample="bilinear"><br><br>>><br><br>>> But isn't bilinear unsuitable for upsampling and some more blurring<br><br>>> method might work better?<br><br>>><br><br>>> -Jukka Rahkonen-<br><br>>><br><br>>><br><br>>><br><br>>> --<br><br>>> Sent from: <a href="http://osgeo-org.1560.x6.nabble.com/GDAL-Dev-f3742093.html" rel="noreferrer" target="_blank">http://osgeo-org.1560.x6.nabble.com/GDAL-Dev-f3742093.html</a><br><br>>> _______________________________________________<br><br>>> gdal-dev mailing list<br><br>>> <a href="mailto:gdal-dev@lists.osgeo.org" target="_blank">gdal-dev@lists.osgeo.org</a><br><br>>> <a href="https://lists.osgeo.org/mailman/listinfo/gdal-dev" rel="noreferrer" target="_blank">https://lists.osgeo.org/mailman/listinfo/gdal-dev</a><br><br><br><br>_______________________________________________<br><br>gdal-dev mailing list<br><br><a href="mailto:gdal-dev@lists.osgeo.org" target="_blank">gdal-dev@lists.osgeo.org</a><br><br><a href="https://lists.osgeo.org/mailman/listinfo/gdal-dev" rel="noreferrer" target="_blank">https://lists.osgeo.org/mailman/listinfo/gdal-dev</a></blockquote></div></div>-- <br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><br>Best Regards!<br><br>Chang Liao,PhD<br>Earth Scientist, Atmospheric Sciences & Global Change Division<br>Pacific Northwest National Laboratory, WA, USA.<br>Email: changliao.climate at <a href="http://gmail.com">gmail.com</a>  or  chang.liao at <a href="http://pnnl.gov">pnnl.gov</a><br>Personal Website: <a href="http://www.changliao.us">http://www.changliao.us</a><br>Skype: changliao1025<br>Lab Website: <a href="http://www.pnnl.gov">www.pnnl.gov</a><br><br></div>