In ArcGIS Pro 2.9, What's going on with time dependent WGS 84 datums?

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01-18-2022 01:24 PM
by Anonymous User
Not applicable

In ArcGIS Pro 2.9 I see multiple realizations of WGS 84 (G172 all the way back to Transit. G2139 hasn't been added yet?).

What is the practical difference between them in ArcGIS Pro 2.9?

Under what circumstances should a user choose one of the named realizations versus 4326?

There are some older posts that deal with this question:

https://community.esri.com/t5/coordinate-reference-systems-questions/what-epoch-is-gcs-wgs-1984-in-1...

https://community.esri.com/t5/mobile-gis-questions/transformations-between-various-nad83-and-wgs84/m...

https://community.esri.com/t5/coordinate-reference-systems-questions/what-version-of-wgs84-is-in-arc...

 

After reading them, it's still not clear to me how ArcGIS treats different realizations of WGS84.

 

 

6 Replies
Robert_LeClair
Esri Notable Contributor

Pinging @MelitaKennedy about this one.  She's very knowledgeable about coordinate systems, datums, etc.

Zedwards_SIPI
New Contributor III

I would like some clarification on this as well! One would think that the G2139 realization would be there by now. 

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Zedwards_SIPI
New Contributor III

Any more news on this. I am not seeing WGS 84(G2139) in ArcGIS Pro 3.0.3. This realization has been out for nearly 2 years! I know that the differences between WGS 84(G2139) and WGS 84(G1762) is tiny but the current realization should still be usable in ESRI's software. 

(U) NGA keeps the WGS 84 RF closely aligned to the International Terrestrial Reference Frame
(ITRF). This ensures adherence to international standards and facilitates interoperability with other
GNSS. In this pursuit, a new realization of WGS 84 RF was introduced on January 3, 2021 that removed
small systematic biases with respect to ITRF. Accordingly, the current frame is designated WGS
84(G2139) and replaces WGS 84(G1762’). WGS 84(G2139) is coincident with ITRF14(IGb14) for the
purposes of positioning and navigation.
(U) Table 1 lists the 7-parameter transformation for (G1762’) – to – (G2139). Using a mean Earth
radius of 6,371,000 meters; the translations are sub-centimeter and the rotations are negligible but the
scale change imparts a height adjustment of -2.8 centimeters at this mean radius.
Table 1. 7-parameter transformation from WGS 84(G1762’) to WGS 84(G2139)
Translation in x 0.0058 meters
Translation in y -0.0064 meters
Translation in z 0.0070 meters
Angular displacement in x 0.08 milli-arc-seconds
Angular displacement in y 0.04 milli-arc-seconds
Angular displacement in z 0.12 milli-arc-seconds
Scale factor -4.4 parts-per-billion

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IrinaRodriguez
New Contributor

following this subject. We need an update for the WGS 84(G2139)

IrinaRodriguez_0-1674757542923.png

 

Zedwards_SIPI
New Contributor III

Anyone? Bueller?

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Robert_LeClair
Esri Notable Contributor

ArcGIS Pro 3.1 is supposed to be released Q1 2023.  Hopeful the new WGS1984 (G2139) is added.

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