[PROJ] setting default transformation NAD83 CSRS to / from NAD83 Original

[Travis Kirstine]

Thanks Even!

From: Even Rouault <even.rouault at spatialys.com>
Sent: Wednesday, April 9, 2025 3:23 PM
To: Travis Kirstine <tkirstine at firstbasesolutions.com>; proj at lists.osgeo.org
Subject: Re: [PROJ] setting default transformation NAD83 CSRS to / from NAD83 Original

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Travis,

in EPSG, the grid ON83CSv1 is registered for the transformation between NAD83 original and NAD83(CSRS) v3. Note the v3 suffix. So instead of UTM NAD83 CSRS (epsg:2958) you need to use "NAD83(CSRS)v3 / UTM zone 17N" (epsg:22317)

$ projinfo -s EPSG:22317 -t EPSG:26917 --spatial-test intersects -o PROJ --single-line -q
+proj=pipeline +step +inv +proj=utm +zone=17 +ellps=GRS80 +step +inv +proj=hgridshift +grids=ca_nrc_ON83CSv1.tif +step +proj=utm +zone=17 +ellps=GRS80

$ echo 500000 5000000 | PROJ_NETWORK=ON PROJ_DEBUG=2 bin/cs2cs EPSG:22317 EPSG:26917
[...]
Using https://cdn.proj.org/ca_nrc_ON83CSv1.tif
500000.08    5000000.32 0.00

Even


Le 09/04/2025 à 20:58, Travis Kirstine via PROJ a écrit :
Hi All,

I’ve been struggling with trying to set proj to use ca_nrc_ON27CSv1.tif grid as the default transformation when transforming between UTM NAD83 CSRS (epsg:2958) and UTM NAD83 (epsgL26917) Original.

In the past I’ve specified the +nadgrids=./ON83CSv1.gsb in the cs2cs command but was hoping that I could just set the default value in the proj.db to apply the gridshift.

Is this possible?  I’ve run the projsync to pull the new version of the grid but still no luck.

Regards



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