North American Datum 1927 (CGQ77)
EPSG
Geodetic Service of Quebec. Contact alain.bernard@mrn.gouv.qc.ca
2002-07-13
Transformation of coordinates at 1m to 2m level of accuracy.
Uses NT method which expects longitudes positive west; EPSG GeogCRSs NAD27(CGQ77) (code 4609) and NAD83(CSRS) (code 4617) have longitudes positive east. Can be taken as an approximate transformation NAD27(CGQ77) to WGS 84 - see code 1691.
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Definition: OGC Well Known Text 2 (2019)
COORDINATEOPERATION["NAD27(CGQ77) to NAD83(CSRS) (1)", VERSION["SGQ-Can QC"], SOURCECRS[ GEOGCRS["NAD27(CGQ77)", DATUM["North American Datum 1927 (CGQ77)", ELLIPSOID["Clarke 1866",6378206.4,294.978698213898, LENGTHUNIT["metre",1]]], PRIMEM["Greenwich",0, ANGLEUNIT["degree",0.0174532925199433]], CS[ellipsoidal,2], AXIS["geodetic latitude (Lat)",north, ORDER[1], ANGLEUNIT["degree",0.0174532925199433]], AXIS["geodetic longitude (Lon)",east, ORDER[2], ANGLEUNIT["degree",0.0174532925199433]], ID["EPSG",4609]]], TARGETCRS[ GEOGCRS["NAD83(CSRS)", DATUM["NAD83 Canadian Spatial Reference System", ELLIPSOID["GRS 1980",6378137,298.257222101, LENGTHUNIT["metre",1]]], PRIMEM["Greenwich",0, ANGLEUNIT["degree",0.0174532925199433]], CS[ellipsoidal,2], AXIS["geodetic latitude (Lat)",north, ORDER[1], ANGLEUNIT["degree",0.0174532925199433]], AXIS["geodetic longitude (Lon)",east, ORDER[2], ANGLEUNIT["degree",0.0174532925199433]], ID["EPSG",4617]]], METHOD["NTv2", ID["EPSG",9615]], PARAMETERFILE["Latitude and longitude difference file","CGQ77-98.gsb"], OPERATIONACCURACY[1.5], USAGE[ SCOPE["Transformation of coordinates at 1m to 2m level of accuracy."], AREA["Canada - Quebec."], BBOX[44.99,-79.85,62.62,-57.1]], ID["EPSG",1845], REMARK["Uses NT method which expects longitudes positive west; EPSG GeogCRSs NAD27(CGQ77) (code 4609) and NAD83(CSRS) (code 4617) have longitudes positive east. Can be taken as an approximate transformation NAD27(CGQ77) to WGS 84 - see code 1691."]]
Definition: JavaScript (Proj4js)
proj4.defs("EPSG:1845","+proj=pipeline +step +proj=axisswap +order=2,1 +step +proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=hgridshift +grids=ca_nrc_CQ77SCRS.tif +step +proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap +order=2,1");
Definition: JSON
{ "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json", "type": "Transformation", "name": "NAD27(CGQ77) to NAD83(CSRS) (1)", "source_crs": { "type": "GeographicCRS", "name": "NAD27(CGQ77)", "datum": { "type": "GeodeticReferenceFrame", "name": "North American Datum 1927 (CGQ77)", "ellipsoid": { "name": "Clarke 1866", "semi_major_axis": 6378206.4, "semi_minor_axis": 6356583.8 } }, "coordinate_system": { "subtype": "ellipsoidal", "axis": [ { "name": "Geodetic latitude", "abbreviation": "Lat", "direction": "north", "unit": "degree" }, { "name": "Geodetic longitude", "abbreviation": "Lon", "direction": "east", "unit": "degree" } ] }, "id": { "authority": "EPSG", "code": 4609 } }, "target_crs": { "type": "GeographicCRS", "name": "NAD83(CSRS)", "datum": { "type": "GeodeticReferenceFrame", "name": "NAD83 Canadian Spatial Reference System", "ellipsoid": { "name": "GRS 1980", "semi_major_axis": 6378137, "inverse_flattening": 298.257222101 } }, "coordinate_system": { "subtype": "ellipsoidal", "axis": [ { "name": "Geodetic latitude", "abbreviation": "Lat", "direction": "north", "unit": "degree" }, { "name": "Geodetic longitude", "abbreviation": "Lon", "direction": "east", "unit": "degree" } ] }, "id": { "authority": "EPSG", "code": 4617 } }, "method": { "name": "NTv2", "id": { "authority": "EPSG", "code": 9615 } }, "parameters": [ { "name": "Latitude and longitude difference file", "value": "CGQ77-98.gsb", "id": { "authority": "EPSG", "code": 8656 } } ], "accuracy": "1.5", "scope": "Transformation of coordinates at 1m to 2m level of accuracy.", "area": "Canada - Quebec.", "bbox": { "south_latitude": 44.99, "west_longitude": -79.85, "north_latitude": 62.62, "east_longitude": -57.1 }, "id": { "authority": "EPSG", "code": 1845 }, "remarks": "Uses NT method which expects longitudes positive west; EPSG GeogCRSs NAD27(CGQ77) (code 4609) and NAD83(CSRS) (code 4617) have longitudes positive east. Can be taken as an approximate transformation NAD27(CGQ77) to WGS 84 - see code 1691." }
Definition: MapServer - MAPfile
PROJECTION "proj=pipeline" "step" "proj=axisswap" "order=2,1" "step" "proj=unitconvert" "xy_in=deg" "xy_out=rad" "step" "proj=hgridshift" "grids=ca_nrc_CQ77SCRS.tif" "step" "proj=unitconvert" "xy_in=rad" "xy_out=deg" "step" "proj=axisswap" "order=2,1" END
Definition: Mapnik
<?xml version="1.0" encoding="utf-8"?> <Map srs="+proj=pipeline +step +proj=axisswap +order=2,1 +step +proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=hgridshift +grids=ca_nrc_CQ77SCRS.tif +step +proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap +order=2,1"> <Layer srs="+proj=pipeline +step +proj=axisswap +order=2,1 +step +proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=hgridshift +grids=ca_nrc_CQ77SCRS.tif +step +proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap +order=2,1"> </Layer> </Map>
Definition: SQL (PostGIS)
INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 1845, 'EPSG', 1845, '+proj=pipeline +step +proj=axisswap +order=2,1 +step +proj=unitconvert +xy_in=deg +xy_out=rad +step +proj=hgridshift +grids=ca_nrc_CQ77SCRS.tif +step +proj=unitconvert +xy_in=rad +xy_out=deg +step +proj=axisswap +order=2,1', 'None');