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All<br>
<br>
Yes we are aware of this California Datum and it was developed by
the <a href="http://sopac-csrc.ucsd.edu/index.php/csrc/">California
Spatial Reference Center</a>
(<a class="moz-txt-link-freetext" href="http://sopac-csrc.ucsd.edu/index.php/csrc/">http://sopac-csrc.ucsd.edu/index.php/csrc/</a>) at the request of
CALTRANS. As suggested with California being on two tectonic plates
with earthquakes that cause large displacements they needed to have
a more updated datum than the time frame that NGS develops them. I
cannot specifically recall the earthquake that initiated this datum
but I think it may have been one near Napa. In my presentations I
highlight the challenges California has due to earthquakes (China
Lake in 2019 cause 6-10 feet of horizontal shift) and from
subsidence (San Joaquin Valley USGS study showed up to 2 feet of
subsidence in 16 months). If interested here is a presentation I
provided that has some of this information
(<a class="moz-txt-link-freetext" href="https://geodesy.noaa.gov/web/science_edu/presentations_library/files/shaw_nsrs_mod_nsgic_20230928.pptx">https://geodesy.noaa.gov/web/science_edu/presentations_library/files/shaw_nsrs_mod_nsgic_20230928.pptx</a>)<br>
<br>
Since Esri is based in California I suspect that is why they
implemented it but this is not an NGS developed datum so I believe
CSRC or CALTRANS would have to submit it to EPSG.<br>
<br>
I hope this helps<br>
Brian<br>
<br>
<div class="moz-cite-prefix">On 1/26/2024 11:02 AM, Even Rouault via
PROJ wrote:<br>
</div>
<blockquote type="cite"
cite="mid:13d8d8fc-5368-4cce-9e78-bd7ee746f197@spatialys.com">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<p>Hi,</p>
<p>interesting... It is known by ESRI as <a
class="moz-txt-link-freetext"
href="https://spatialreference.org/ref/esri/104024/"
moz-do-not-send="true">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"
moz-do-not-send="true">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"
moz-do-not-send="true">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"
moz-do-not-send="true">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">
<meta http-equiv="content-type"
content="text/html; charset=UTF-8">
<div dir="ltr">
<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>
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<pre class="moz-signature" cols="72">--
*************************************
Brian Shaw
Rocky Mountain Regional Advisor (CO, MT, WY)
NOAA's National Geodetic Survey (NGS)
Cell Phone # 240-988-6363</pre>
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