Investigate adding CSRS Datum Grid Shift File Support

[proj4-bot]

Reported by warmerdam on 13 Dec 2012 21:39 UTC
The Canadian CSRS (Canadian Spatial Reference System) datum as used in EPSG:2958 - NAD83(CSRS) / UTM zone 17N can be related to NAD83 via a grid shift file. This ticket is to track reviewing the source and how to integrate with PROJ.4.

"""
We acquired the gridshift file from the Ontario government (COSINE), I believe that they are free but you will need to sign up to get access:

http://www.cosine.mnr.gov.on.ca

Also ESRI Canada has posted a table of where to get the various grid shift file for each province

http://www.esri.ca/en/content/projections-and-transformations-canada
"""

Migrated-From: https://trac.osgeo.org/proj/ticket/202

[rskelly]

I believe it's already possible to do CSRS transformations using the appropriate Helmert parameters and grid shift files which can be obtained with the TRX program (Win only). I made a script to convert the grid shift files to TIF, but it could easily be ported to produce GTX files, which proj can use: https://github.com/rskelly/geotools/blob/master/scripts/gvb2tif.py.

There are some references in the header of that file.

[kbevers]

Closing since all links in this ticket are dead. If the issue is important enough to someone it will show up again.

[rskelly]

Not suggesting reopening but if anyone's interested, the file is here: http://dijital.ca/files/gvb2tif.txt

It may be out of date now.

[maphew]

Esri Canada's list of provincial grid shift files between NAD 83 Original and NAD 83 CSRS: https://resources.esri.ca/getting-technical/your-guide-to-canadian-datum-transformations-and-arcgis-online-part-3 (2019-May-27)

Current gvb2tif seems to be: https://github.com/zxgdll/geotools/tree/master/scripts

TRX program is from here https://webapp.geod.nrcan.gc.ca/geod/tools-outils/applications.php#trx. A free account is needed to download, but the application and data are declared as "Use of Canadian Geodetic Survey products and data is subject to the Open Government Licence - Canada", which in turn declares in part "You are free to: Copy, modify, publish, translate, adapt, distribute or otherwise use the Information in any medium, mode or format for any lawful purpose.". There is no explicit license contained in the download archive. The license terms one must agree to on install are about NRCAN is the author, the crown is copyright holder, and no warranty. In other words nothing contravenes the generic open license on the download page.

NAD83(CSRS)v7 including vertical height adjustment from Nrcan is here, no sign-in wall:
https://webapp.geod.nrcan.gc.ca/geod/tools-outils/nad83-docs.php
It would be for older CSRS to newer CSRS, not for Original to CSRS.

[rouault]

Reopening as there is new info
Looking at the esri.ca page and the table, I can find that the grids they mention are also referenced in EPSG:

INSERT INTO "grid_transformation" VALUES('EPSG','9244','NAD83 to NAD83(CSRS)v4 (3)','This gridded difference file AB_CSRS.DAC will need to be renamed to AB_CSRS.gsb to run in some software suites. Formats identical, but AB file is provincial fit only. Can be taken as an approximate transformation NAD83 to WGS 84 - see code 1702.','Accuracy 1-2 metres.','EPSG','9615','NTv2','EPSG','4269','EPSG','8246','EPSG','2376',1.5,'EPSG','8656','Latitude and longitude difference file','AB_CSRS.DAC',NULL,NULL,NULL,NULL,NULL,NULL,'AB Env-Can AB',0);
INSERT INTO "grid_transformation" VALUES('EPSG','9116','NAD83 to NAD83(CSRS)v2 (6)','Derived through NAD83(CSRS)v2. Replaced by NAD83 to NAD83(CSRS) (7) (CT code 9117) for CRD, NAD83 to NAD83(CSRS) (8) (CT code 9118) for north Vancouver Island and NAD83 to NAD83(CSRS) (9) (CT code 9119) for mainland.','Spatial referencing.','EPSG','9615','NTv2','EPSG','4269','EPSG','8237','EPSG','2832',0.1,'EPSG','8656','Latitude and longitude difference file','BC_93_98.GSB',NULL,NULL,NULL,NULL,NULL,NULL,'GeoBC-Can BC CSRSv2',0);
INSERT INTO "grid_transformation" VALUES('EPSG','9110','NAD83 to NAD83(CSRS)v3 (5)','Derived through NAD83(CSRS)v3.','Spatial referencing.','EPSG','9615','NTv2','EPSG','4269','EPSG','8240','EPSG','1367',0.1,'EPSG','8656','Latitude and longitude difference file','ON83CSv1.GSB',NULL,NULL,NULL,NULL,NULL,NULL,'LIO-Can Ont',0);
INSERT INTO "grid_transformation" VALUES('EPSG','9241','NAD83 to NAD83(CSRS)v2 (1)','Uses NT method which expects longitudes positive west; EPSG GeogCRSs NAD83 (code 4269) and NAD83(CSRS) (code 4617) have longitudes positive east. Can be taken as an approximate transformation NAD83 to WGS 84 - see code 1696.','Accuracy 1-2 metres.','EPSG','9615','NTv2','EPSG','4269','EPSG','8237','EPSG','1368',1.5,'EPSG','8656','Latitude and longitude difference file','NAD83-98.gsb',NULL,NULL,NULL,NULL,NULL,NULL,'SGQ-Can QC',0);
INSERT INTO "grid_transformation" VALUES('EPSG','9243','NAD83 to NAD83(CSRS)v3 (2)','Can be taken as an approximate transformation NAD83 to WGS 84 - see code 1697.','Accuracy 1-2 metres.','EPSG','9615','NTv2','EPSG','4269','EPSG','8240','EPSG','2375',1.5,'EPSG','8656','Latitude and longitude difference file','SK83-98.gsb',NULL,NULL,NULL,NULL,NULL,NULL,'SK PMC-Can SK',0);