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<p class="MsoNormal">Hi all, <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoPlainText">I have an issue with the GRIB2 WCS GetCoverage output using MapServer and a custom EPSG file. I'm using MapServer version 7.6.2, GDAL 3.1.3 and proj 7.2.0.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">I have a Mapfile using a GRIB2 file as input data (with DATA in the mapfile) and I am trying to do a
<i>WCS 2.0.1 GetCoverage</i> request for a subset of the layer related to the GRIB2. You can get a raw file example here using
<i>curl</i> (command: <i>curl -o tmp.grib2 "<a href="https://dd.weather.gc.ca/model_gem_global/15km/grib2/lat_lon/12/006/CMC_glb_TMP_TGL_2_latlon.15x.15_2021071412_P006.grib2">https://dd.weather.gc.ca/model_gem_global/15km/grib2/lat_lon/12/006/CMC_glb_TMP_TGL_2_latlon.15x.15_2021071412_P006.grib2</a>"</i>)<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">I know my layer works fine in WMS and in WCS using the NetCDF and GeoTIFF output. Here is a small mapfile that shows this behavior as well as the EPSG file I’m using.<br>
mapfile: <span style="color:red"><a href="https://pastebin.com/Pq06D0LQ">https://pastebin.com/Pq06D0LQ</a>
<br>
</span>EPSG file: <a href="https://pastebin.com/7wfCjVdb">https://pastebin.com/7wfCjVdb</a><o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">I also tested the file with <i>shp2img</i> (command:<i> shp2img -m grib2.map -o ttt.png -all_debug 5</i>) and it outputs a valid image (see valid image here:
<a href="https://ibb.co/mRD5YyC">https://ibb.co/mRD5YyC</a>)<span style="color:red"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here are <i>WCS GetCoverage</i> mapserv commands that outputs a valid subset of my GRIB2 layer in GeoTIFF and NetCDF:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="font-family:Symbol"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><i>mapserv -nh "QUERY_STRING=map=grib2.map&SERVICE=WCS&VERSION=2.0.1&REQUEST=GetCoverage&COVERAGEID=TEST&SUBSETTINGCRS=EPSG:4326&SUBSET=x(-120,-85)&SUBSET=y(48,66)&RESOLUTION=x(0.24)&RESOLUTION=y(0.24)&FORMAT=image/tiff" > tmp.tiff<o:p></o:p></i></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="font-family:Symbol"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><i>mapserv -nh "QUERY_STRING=map=grib2.map&SERVICE=WCS&VERSION=2.0.1&REQUEST=GetCoverage&COVERAGEID=TEST&SUBSETTINGCRS=EPSG:4326&SUBSET=x(-120,-85)&SUBSET=y(48,66)&RESOLUTION=x(0.24)&RESOLUTION=y(0.24)&FORMAT=image/netcdf" > tmp.nc<o:p></o:p></i></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The problem is the following: If I use the same request to output a GRIB2 file, I get an error:
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><u>Request</u><i><o:p></o:p></i></p>
<p class="MsoNormal"><i>mapserv -nh "QUERY_STRING=map=grib2.map&SERVICE=WCS&VERSION=2.0.1&REQUEST=GetCoverage&COVERAGEID=TEST&SUBSETTINGCRS=EPSG:4326&SUBSET=x(-120,-85)&SUBSET=y(48,66)&RESOLUTION=x(0.24)&RESOLUTION=y(0.24)&FORMAT= application/x-grib2"<o:p></o:p></i></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><u>Error<o:p></o:p></u></p>
<p class="MsoNormal"><i><ows:ExceptionText>msWCSWriteFile20(): General error message. msSaveImage() failed<o:p></o:p></i></p>
<p class="MsoNormal"><i>msSaveImageGDAL(): General error message. Failed to create output GRIB file.<o:p></o:p></i></p>
<p class="MsoNormal"><i>Unsupported or missing spatial reference system</ows:ExceptionText><o:p></o:p></i></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here are the debug MapServer lines: <a href="https://pastebin.com/pT9WHvGP">
https://pastebin.com/pT9WHvGP</a>. I know there are a lot of debugs errors showing “<i>PROJ: Debug: proj_create: Cannot find proj.db</i>” but this does not seem to cause issues with other formats then GRIB2 or in WMS requests.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">This error only appears when doing a WCS request for GRIB2 output. Also, if I comment out the line
<b>CONFIG "PROJ_LIB" "./"</b> , I get a valid GRIB2 file as output. I tried using a
<i>proj.db</i> file instead and point to it in my CONFIG line, but it also fail with the same error.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Any ideas why only the GRIB2 <i>WCS GetCoverage</i> request fails with my custom EPSG file while the other WMS requests or WCS output formats work fine ?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="FR-CA">Thanks<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="FR-CA"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="FR-CA">LP<o:p></o:p></span></p>
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