I am also using the netCDF driver to read weather data from a thredds server. I am curious how the tag names for the metadata were defined in the driver. For example, the CF convention for the central meridian is "longitude_of_central_meridian" and in the netCDF driver it is "central_meridian". This causes the true value to be skipped and set to a default value of 0.0 in my case.<br>
<br>regards,<br><br clear="all"># ===================<br>Kyle Shannon<br>Physical Science Technician<br>RMRS Fire Sciences Lab<br>Fire, Fuels & Smoke - RWU 4405<br>
5775 Highway 10 W.<br>Missoula, MT 59808<br>(406) 829-6954<br><a href="mailto:kshannon@fs.fed.us" target="_blank">kshannon@fs.fed.us</a><br># ===================<br>
<br><br><div class="gmail_quote">On Thu, Jan 28, 2010 at 3:52 PM, Bruce Raup <span dir="ltr"><<a href="mailto:bruceraup@gmail.com" target="_blank">bruceraup@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Frank,<br>
<br>
Thanks for the reply. I mistakenly said GeoRef when I meant to say<br>
GeoTransform. Your description of what would happen if we make the<br>
change confirms what we thought.<br>
<br>
I think we will go ahead and make the change, and file a ticket. Lots<br>
of data are in polar projections, and it seems like a small amount of<br>
work now could save a lot of confusion in the future.<br>
<br>
Best regards,<br>
Bruce<br>
<div><div></div><div><br>
<br>
On Wed, Jan 27, 2010 at 17:44, Frank Warmerdam <<a href="mailto:warmerdam@pobox.com" target="_blank">warmerdam@pobox.com</a>> wrote:<br>
> On Wed, Jan 27, 2010 at 2:22 AM, Bruce Raup <<a href="mailto:bruceraup@gmail.com" target="_blank">bruceraup@gmail.com</a>> wrote:<br>
><br>
>> We propose using terms such as<br>
>><br>
>> grid_top_boundary_projected_y<br>
>> grid_bottom_boundary_projected_y<br>
>> grid_left_boundary_projected_x<br>
>> grid_right_boundary_projected_x<br>
>><br>
>> Alternatively, grid corner coordinates could be used.<br>
>><br>
>> What would the impacts of such a change of names in our files be? If<br>
>> the GeoRef field is also in the file, would it break existing software<br>
>> for being able to navigate (geolocate) the data? And, would the<br>
>> community consider the adoption of more universal terms more generally<br>
>> (i.e. in GDAL itself)?<br>
><br>
> Bruce,<br>
><br>
> I am not really an expert on the GDAL netcdf driver, but<br>
> I will attempt to respond.<br>
><br>
> First, I think it would be better to just document that the<br>
> existing tag names (eg. northernmost_northing) should<br>
> just be interpreted with the new definitions<br>
> (grid_top_boundary_projected_y) rather than trying<br>
> to change the actual tag names in order to gain some<br>
> possibly clarity in less common situations.<br>
><br>
> I have reviewed the GDAL netcdf driver and it seems to<br>
> look for two things. First a GeoTransform value (which I<br>
> think is only a GDAL convention). If that is not found it<br>
> looks for northernmost_northing, etc. I presume these are<br>
> part of the CF conventions, though I don't know for sure.<br>
><br>
> I do no see any reference to a "GeoRef" tag.<br>
><br>
> So if you make the planned change, and if you do not<br>
> also provide the GeoTransform then older versions of<br>
> GDAL would not be able to read the georeferencing of<br>
> the files. I presume this might also be the case of<br>
> almost all other software, even if you did support<br>
> GeoTransform.<br>
><br>
> However, if you do go ahead with this convention, then<br>
> please file ticket with a small sample file so we can add<br>
> support for it.<br>
><br>
> Best regards,<br>
> --<br>
> ---------------------------------------+--------------------------------------<br>
> I set the clouds in motion - turn up | Frank Warmerdam, <a href="mailto:warmerdam@pobox.com" target="_blank">warmerdam@pobox.com</a><br>
> light and sound - activate the windows | <a href="http://pobox.com/%7Ewarmerdam" target="_blank">http://pobox.com/~warmerdam</a><br>
> and watch the world go round - Rush | Geospatial Programmer for Rent<br>
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><br>
<br>
<br>
<br>
</div></div><font color="#888888">--<br>
Bruce Raup<br>
<a href="http://cires.colorado.edu/%7Ebraup/" target="_blank">http://cires.colorado.edu/~braup/</a><br>
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