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<p>Le 22/08/2022 à 17:05, Lesparre, Jochem via PROJ a écrit :</p>
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<blockquote type="cite"
cite="mid:AM0P192MB0482D3B3804D6D6C37AA96C7EF719@AM0P192MB0482.EURP192.PROD.OUTLOOK.COM">
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<p class="MsoNormal"><span style="mso-fareast-language:EN-US"
lang="EN-GB">I support:<o:p></o:p></span></p>
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style="margin-left:0cm;mso-list:l0 level1 lfo1"><span
style="mso-fareast-language:EN-US" lang="EN-GB"> (…snip…)<o:p></o:p></span></li>
<li class="MsoListParagraph"
style="margin-left:0cm;mso-list:l0 level1 lfo1"><span
style="mso-fareast-language:EN-US" lang="EN-GB">Greg’s
suggestion to stop using WGS84 (EPSG:4326).</span></li>
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<p>Just one nuance about above last point. I agree about deprecating
EPSG:4326 for <i>data producers</i> (i.e. encourage all data
producers to describe their CRS as accurately as they can). But we
still need EPSG:4326 as an ensemble (i.e. with its ~2 meters
uncertainty) for <i>data users</i>. The reason is that when a
software reads a file from unknown source, if the CRS has not been
accurately defined by the producer, there is nothing the software
or user can do about that. In those cases, the worst thing would
be to <i>pretend</i> that we have a CRS of some specific
realization while actually the software has no idea. We need a way
to said "we don't know what is the realization because the
producer did not tell us, expect a 2 meters uncertainty".</p>
<p>So I would not be in favour of interpreting EPSG:4326 as the
latest realization. I think it should continue to mean "we don't
know the realization", and every coordinate transformation
involving EPSG:4326 should declare a 2 meters uncertainty. We need
to keep the possibility to said "we don't know", even if we want
to encourage data producers to be more accurate.<br>
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<p> Martin</p>
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