[PROJ] Different behaviour between 9.7.1 and 9.8.0

[Even Rouault]

Javier,

I suspect this is due to commit 3717ff00afa6872a2ae581de929ba5559ff84438 
where I tweaked transformations_czechia.sql, presumably to make existing 
tests pass following to the addition of "ETRS89-CZE [2007]". Only a git 
bisect session would confirm

Even

Le 10/03/2026 à 16:43, Javier Jimenez Shaw via PROJ a écrit :
> Hi
>
> This change in behaviour is a surprise to me. I would like to know 
> what changed (I know the ETRS89 datum ensemble, but I was not 
> expecting this consequence)
>
> Note: I do not want to change it, just to understand it.
>
> Context: Going from EPSG:4258 (--3d) to EPSG:5514+8357 is using 
> both cz_cuzk_CR-2005.tif and cz_cuzk_table_-y-x_3_v1710.tif in 9.7.1 
> and 9.8.0
>
> The difference is going from EPSG:4326 (--3d) to EPSG:5514+8357. In 
> 9.7.1 it is not using cz_cuzk_table_-y-x_3_v1710.tif, but in 9.8.0 it 
> does. (both use cz_cuzk_CR-2005.tif)
>
> What changed? PROJ, EPSG, both?
>
> Thank you.
> Javier
>
> PROJ 9.8.0:
> PROJ_NETWORK=ON ./proj_9.8.0/bin/projinfo EPSG:4326 EPSG:5514+8357 
> --3d --spatial-test intersects --bbox 15,50,15.1,50.1 -o proj | head -n 40
> Candidate operations found: 12
> -------------------------------------
> Operation No. 1:
>
> unknown id, Inverse of ETRS89-CZE [2007] to WGS 84 (1) + ETRS89-CZE 
> [2007] to Baltic 1957 height (2) + Inverse of S-JTSK/05 to ETRS89-CZE 
> [2007] (1) + Modified Krovak East North (Greenwich) + Inverse of 
> S-JTSK / Krovak East North (EPSG:5514) to S-JTSK/05 / Modified Krovak 
> East North (EPSG:5516) + Inverse of Krovak East North (Greenwich) + 
> Krovak East North (Greenwich), 1.065 m, Czechia.
>
> ... pipeline omitted. It uses cz_cuzk_CR-2005.tif 
> and cz_cuzk_table_-y-x_3_v1710.tif
>
> PROJ 9.7.1:
> PROJ_NETWORK=ON ./proj_9.7.1/bin/projinfo EPSG:4326 EPSG:5514+8357 
> --3d --spatial-test intersects --bbox 15,50,15.1,50.1 -o proj | head -n 40
> Candidate operations found: 7
> -------------------------------------
> Operation No. 1:
>
> unknown id, Inverse of ETRS89 to WGS 84 (1) + ETRS89 to Baltic 1957 
> height (2) + Inverse of S-JTSK to ETRS89 (1) + Krovak East North 
> (Greenwich), 2.03 m, Czechia.
>
> ... pipeline omitted. It only uses cz_cuzk_CR-2005.tif
>
>
> As a reference, from EPSG:4258 it doing this
>
> PROJ_NETWORK=ON ./proj_9.8.0/bin/projinfo EPSG:4258 EPSG:5514+8357 
> --3d --spatial-test intersects --bbox 15,50,15.1,50.1 -o proj | head -n 40
> Candidate operations found: 10
> -------------------------------------
> Operation No. 1:
>
> PROJ:ETRS89_3D_TO_S_JTSK_E_N_BALTIC_HEIGHT, ETRS89 to S-JTSK / Krovak 
> East North + Baltic 1957 height, 0.05 m, Czechia.
>
> ... pipeline omitted. It uses cz_cuzk_CR-2005.tif 
> and cz_cuzk_table_-y-x_3_v1710.tif
>
>
>
>
>
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