[PROJ] CSRS Epoch 2017.50 (NAD83)

[Even Rouault]

Hi,

interesting... It is known by ESRI as 
https://spatialreference.org/ref/esri/104024/ but AFAICS, there isn't 
any transformation registered in their database between this datum and 
other North American datums.

There's a slide deck talking about it, where HTDP is mentionned 
(https://www.ngs.noaa.gov/TOOLS/Htdp/Htdp.html) : 
https://geodesy.noaa.gov/geospatial-summit/year-2019/files/martin-coordinates-moving.pptx 
, 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.

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 
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 
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!

Even

Le 26/01/2024 à 18:24, Javier Jimenez Shaw via PROJ a écrit :
> Hi
>
> I discovered today that there is a datum in California called "CSRS 
> Epoch 2017.50 (NAD83)"
> http://geoweb99.ucsd.edu/index.php/epoch2017/
> http://sopac-csrc.ucsd.edu/
>
> "CSRS Epoch 2017.50(NAD83) replaces the previous “CSRS Epoch 2011.00 
> ITRF2005 NAD83(NSRS2007)” datum that included coordinates for 830 CSRN 
> stations."
>
> 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)
> How can it be used with PROJ?
>
> (Is it normal that some states use their own datum in the US? It is 
> not enough with hundred of State Planes ;)
>
> Cheers,
> Javier.
>
> PS. Be careful with the acronyms:
> CRS: Coordinate Reference System
> CSRC: California Spatial Reference Center
> CSRS: California Spatial Reference System
> NAD83(CSRS): Canadian Spatial Reference System
>
> So "NAD83(CSRS)" and "CSRS (NAD83)" are not the same.
>
> .___ ._ ..._ .. . ._.  .___ .. __ . _. . __..  ... .... ._ .__
>
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