[PROJ] CSRS Epoch 2017.50 (NAD83)

[Brian Shaw]

All

Yes we are aware of this California Datum and it was developed by the 
California Spatial Reference Center 
<http://sopac-csrc.ucsd.edu/index.php/csrc/> 
(http://sopac-csrc.ucsd.edu/index.php/csrc/) 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 
(https://geodesy.noaa.gov/web/science_edu/presentations_library/files/shaw_nsrs_mod_nsgic_20230928.pptx)

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.

I hope this helps
Brian

On 1/26/2024 11:02 AM, Even Rouault via PROJ wrote:
>
> 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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>
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-- 
*************************************
Brian Shaw
Rocky Mountain Regional Advisor (CO, MT, WY)
NOAA's National Geodetic Survey (NGS)
Cell Phone # 240-988-6363
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