[PROJ] World area of use

[Melita Kennedy]

Hello Javier,

Disclosure: I'm a member of the subcommittee that maintains the EPSG registry. I also work for Esri.

I'm sorry that I took so long to respond. I haven't been keeping up with the list. My colleague, Bojan, had forwarded your message to me but it while I was on vacation and got buried. 

You can sometimes find information about why the subcommittee makes certain decisions in the Guidance Notes, https://epsg.org/guidance-notes.html

Guidance Note 7-6 is EPSG policies and procedures for EPSG Dataset data management, documents strategy for populating the EPSG Dataset. 

It includes a small section on extents with this bit about World extents: 

"There are two extent records for the whole world, code 2830 includes and code 1262 excludes, the names of all countries. The description for 2830 is lengthy -- over 3000 characters. It is used for entities that might be wanted from a text string using country name. Code 1262 is used when a short description is appropriate." 

Do you feel we should expand the section or double-check that the choice of extent code is consistent? Feel free to ask me to bring it up to the subcommittee or send an email yourself using the online form at https://epsg.org/contact.html.

It's also tied to an option you have when logged in, "Include World Items". We recently discussed whether to move more objects in/out of that category like the ITRF definitions.

Regards,
Melita

-- 
Melita Kennedy
Principal Product Engineer
Esri, Inc.
mkennedy at esri.com

======================================================


From: PROJ <proj-bounces at lists.osgeo.org (mailto:proj-bounces at lists.osgeo.org)> On Behalf Of Even Rouault via PROJ
Sent: Saturday, December 30, 2023 11:18 AM
To: Javier Jimenez Shaw <j1 at jimenezshaw.com (mailto:j1 at jimenezshaw.com)>; proj <PROJ at lists.osgeo.org (mailto:PROJ at lists.osgeo.org)>
Subject: Re: [PROJ] World area of use

Hi Javier,
I don't know the reason for the difference, but if there's one, it would be interesting to know, and if there's none, converging to World (without country list, extent 1262) would indeed seem better. Looking at the few instances that use World by country (extent 2830), there is no apparent logic. It isn't even related to the type (geographic 2D vs 3D vs geocentric).
Grep'ping in the change items of the registry (grep epsg_change PostgreSQL_Data_Script.sql | grep 1262 | grep 2830), shows a global trend of moving from 2830 to 1262 (with a interesting back & forth for CRS 8227, IGS14 geocentric, which was changed from 1262 to 2830, and then later back to 1262)
Even
Le 30/12/2023 à 19:54, Javier Jimenez Shaw via PROJ a écrit :
Hi

Playing with crs-explorer, I found that there are a few (and only a few) CRSs with an endless "area of use" description:
?latlng=-45.435465,-15.468750&ignoreWorld=false&allowDeprecated=false&authorities=EPSG&activeTypes=GEOGRAPHIC_2D_CRS,GEOGRAPHIC_3D_CRS,GEOCENTRIC_CRS [crs-explorer.proj.org] (https:/crs-explorer.proj.org/?latlng=-45.435465,-15.468750&ignoreWorld=false&allowDeprecated=false&authorities=EPSG&activeTypes=GEOGRAPHIC_2D_CRS,GEOGRAPHIC_3D_CRS,GEOCENTRIC_CRS (https://urldefense.com/v3/__https:/crs-explorer.proj.org/?latlng=-45.435465,-15.468750&ignoreWorld=false&allowDeprecated=false&authorities=EPSG&activeTypes=GEOGRAPHIC_2D_CRS,GEOGRAPHIC_3D_CRS,GEOCENTRIC_CRS__;!!CKZwjTOV!2uziJJtS5R3htvY33qmdDN1rJ-yl23YUiU7NAtFcJgQ3laCDfCl5lFah7a66_RTDPzQIdD-o6GRn$))

In EPSG called "World (by country)" World-by-country.html [epsg.org] (https:/epsg.org/extent_2830/World-by-country.html (https://urldefense.com/v3/__https:/epsg.org/extent_2830/World-by-country.html__;!!CKZwjTOV!2uziJJtS5R3htvY33qmdDN1rJ-yl23YUiU7NAtFcJgQ3laCDfCl5lFah7a66_RTDPzQIdPBiEOeG$))

like
EPSG:4326 [epsg.org] (https:/epsg.org/crs_4326/WGS-84.html (https://urldefense.com/v3/__https:/epsg.org/crs_4326/WGS-84.html__;!!CKZwjTOV!2uziJJtS5R3htvY33qmdDN1rJ-yl23YUiU7NAtFcJgQ3laCDfCl5lFah7a66_RTDPzQIdJmPB8XQ$))
WGS 84
EPSG:9754 [epsg.org] (https:/epsg.org/crs_9754/WGS-84-G2139-.html (https://urldefense.com/v3/__https:/epsg.org/crs_9754/WGS-84-G2139-.html__;!!CKZwjTOV!2uziJJtS5R3htvY33qmdDN1rJ-yl23YUiU7NAtFcJgQ3laCDfCl5lFah7a66_RTDPzQIdBTV_bnb$))
WGS 84 (G2139)


EPSG:9988 [epsg.org] (https:/epsg.org/crs_9988/ITRF2020.html (https://urldefense.com/v3/__https:/epsg.org/crs_9988/ITRF2020.html__;!!CKZwjTOV!2uziJJtS5R3htvY33qmdDN1rJ-yl23YUiU7NAtFcJgQ3laCDfCl5lFah7a66_RTDPzQIdEgAvj6T$))
ITRF2020


EPSG:10176 [epsg.org] (https:/epsg.org/crs_10176/IGS20.html (https://urldefense.com/v3/__https:/epsg.org/crs_10176/IGS20.html__;!!CKZwjTOV!2uziJJtS5R3htvY33qmdDN1rJ-yl23YUiU7NAtFcJgQ3laCDfCl5lFah7a66_RTDPzQIdAY_9M5R$))
IGS20

but not some other implementations like
EPSG:4978 [epsg.org] (https:/epsg.org/crs_4978/WGS-84.html (https://urldefense.com/v3/__https:/epsg.org/crs_4978/WGS-84.html__;!!CKZwjTOV!2uziJJtS5R3htvY33qmdDN1rJ-yl23YUiU7NAtFcJgQ3laCDfCl5lFah7a66_RTDPzQIdOxjP9Ib$))
WGS 84
EPSG:9753 [epsg.org] (https:/epsg.org/crs_9753/WGS-84-G2139-.html (https://urldefense.com/v3/__https:/epsg.org/crs_9753/WGS-84-G2139-.html__;!!CKZwjTOV!2uziJJtS5R3htvY33qmdDN1rJ-yl23YUiU7NAtFcJgQ3laCDfCl5lFah7a66_RTDPzQIdDXobqfV$))
WGS 84 (G2139)


EPSG:9055 [epsg.org] (https:/epsg.org/crs_9055/WGS-84-G1150-.html (https://urldefense.com/v3/__https:/epsg.org/crs_9055/WGS-84-G1150-.html__;!!CKZwjTOV!2uziJJtS5R3htvY33qmdDN1rJ-yl23YUiU7NAtFcJgQ3laCDfCl5lFah7a66_RTDPzQIdBVfUA7V$))
WGS 84 (G1150)

(yes, same CRS. The difference is Geographic 2D vs 3D vs geocentric)

Do you know why this difference?
Is it something to communicate to EPSG?
I personally think that that endless list of countries is not needed when there is a "World" at front.

Cheers and happy new year.
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