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<p>Hi,</p>
<p>interesting... It is known by ESRI as
<a class="moz-txt-link-freetext" href="https://spatialreference.org/ref/esri/104024/">https://spatialreference.org/ref/esri/104024/</a> but AFAICS, there
isn't any transformation registered in their database between this
datum and other North American datums. <br>
</p>
<p>There's a slide deck talking about it, where HTDP is mentionned
(<a class="moz-txt-link-freetext" href="https://www.ngs.noaa.gov/TOOLS/Htdp/Htdp.html">https://www.ngs.noaa.gov/TOOLS/Htdp/Htdp.html</a>) :
<a class="moz-txt-link-freetext" href="https://geodesy.noaa.gov/geospatial-summit/year-2019/files/martin-coordinates-moving.pptx">https://geodesy.noaa.gov/geospatial-summit/year-2019/files/martin-coordinates-moving.pptx</a>
, but I've the feeling the message might be that Californians
found HTDP to not be faithful enough for their purpose. I dunno..
I guess our friends from NGS could confirm or infirm.</p>
<p>I guess the reason for a separate datum is that part of
California is anchored on a separate tectonic plate than the rest
of N.A (or even the parts on the N.A. plate are subject to high
deformation). Presumably this will be obsoleted by the NATRF2022
when it comes into life, and interestingly I found in
<a class="moz-txt-link-freetext" href="https://casetext.com/statute/california-codes/california-public-resources-code/division-8-surveying-and-mapping/chapter-3-geodetic-datums-and-the-california-spatial-reference-network/section-8852-nad83-natrf2022-or-patrf2022">https://casetext.com/statute/california-codes/california-public-resources-code/division-8-surveying-and-mapping/chapter-3-geodetic-datums-and-the-california-spatial-reference-network/section-8852-nad83-natrf2022-or-patrf2022</a>
that states "The official geodetic datum to which horizontal
positions and ellipsoid heights are referenced within the State of
California shall be NAD83, NATRF2022, or PATRF2022". Oh joy!<br>
</p>
<p>Even<br>
</p>
<div class="moz-cite-prefix">Le 26/01/2024 à 18:24, Javier Jimenez
Shaw via PROJ a écrit :<br>
</div>
<blockquote type="cite"
cite="mid:CADRrdKthJ+Fmb8VCG4hKr2NxoqUgXHgupmM0=MT5rC25KRiM8g@mail.gmail.com">
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<div>Hi</div>
<div><br>
</div>
<div>I discovered today that there is a datum in California
called "CSRS Epoch 2017.50 (NAD83)"</div>
<div><a href="http://geoweb99.ucsd.edu/index.php/epoch2017/"
moz-do-not-send="true" class="moz-txt-link-freetext">http://geoweb99.ucsd.edu/index.php/epoch2017/</a></div>
<div><a href="http://sopac-csrc.ucsd.edu/"
moz-do-not-send="true" class="moz-txt-link-freetext">http://sopac-csrc.ucsd.edu/</a></div>
<div><br>
</div>
<div>"CSRS Epoch 2017.50(NAD83) replaces the previous “CSRS
Epoch 2011.00 ITRF2005 NAD83(NSRS2007)” datum that included
coordinates for 830 CSRN stations."</div>
<div><br>
</div>
<div>I have not seen it before, so I guess there is no CRS using
it in EPSG. (I do not find that datum in EPSG)<br>
</div>
<div>How can it be used with PROJ?</div>
<div><br>
</div>
<div>(Is it normal that some states use their own datum in the
US? It is not enough with hundred of State Planes ;)<br>
</div>
<div>
<div><br>
</div>
<div>Cheers,</div>
<div>Javier.</div>
<div><br>
</div>
</div>
<div>PS. Be careful with the acronyms:</div>
<div>CRS: Coordinate Reference System</div>
<div>CSRC: California Spatial Reference Center</div>
<div>CSRS: California Spatial Reference System</div>
<div>NAD83(CSRS): Canadian Spatial Reference System</div>
<div><br>
</div>
<div>So "NAD83(CSRS)" and "CSRS (NAD83)" are not the same.</div>
<br>
<div>
<div dir="ltr" class="gmail_signature"
data-smartmail="gmail_signature">
<div dir="ltr">
<div>.___ ._ ..._ .. . ._. .___ .. __ . _. . __.. ...
.... ._ .__</div>
</div>
</div>
</div>
</div>
<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
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</blockquote>
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