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Javier,
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<div>In the DB, the operation registered is ETRS89_TO_ETRF2020,
so it has to be "inverted". However, I do not see any way to
indicate that in the concatenated operation.<br>
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<div>For instance, this concatenated operation does not mention
that the second step should be "inverted" (if I understood
correctly)<br>
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<div><span style="font-family:monospace"> ('NKG',
'ITRF2014_TO_DK', 1, 'EPSG', '8366'), -- ITRF2014 ->
ETRF2014<br>
('NKG', 'ITRF2014_TO_DK', 2, 'NKG',
'NKG_ETRF14_TO_ETRF2014'),<br>
('NKG', 'ITRF2014_TO_DK', 3, 'NKG', 'PAR_2020_DK'),<br>
('NKG', 'ITRF2014_TO_DK', 4, 'NKG',
'DK_2020_INTRAPLATE')</span></div>
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<div>Does it mean that PROJ is finding it automatically?</div>
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Unfortunately yes, PROJ has to figure out the direction of
operations, and it is an awful and error prone job, especially when
one of the step is a conversion which lacks explicit source and
target CRS. I complained about that to IOGP to ask to add a
direction (forward/inverse) column in the coordinate_step table, but
I wasn't apparently sufficiently convincing.<br>
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<div>Thanks.<br>
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<div>PS Should I add the concatenated operation
(ITRF2020->ETRS89) to PROJ in a PR? There are different
"paths" from ITRF2020 to ETRS89. All apparently equivalent,
but probably not exactly the same.<br>
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<p>Maybe try first to see if EPSG wants to add it?</p>
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<pre class="moz-signature" cols="72">--
<a class="moz-txt-link-freetext" href="http://www.spatialys.com">http://www.spatialys.com</a>
My software is free, but my time generally not.</pre>
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