Coordinate Operations¶

Coordinate operations are used to convert coordinates from a source CRS to a target CRS.

If source and target CRSs are refered to a different datum, a datum transform has to be applied. Datum transforms are not exact, they are determined empirically. For the same pair of CRS, there can be many datum transforms and versions, each one with its own domain of validity and an associated transform error. Given a CRS pair, GeoServer will automatically pick the most accurate datum transform from the EPSG database, unless a custom operation is declared.

Coordinate operations can be queried and tested using the Reprojection Console.
To enable higher accuracy Grid Shift transforms, see Add Grid Shift Transform files.
See Define a custom Coordinate Operation to declare new operations. Custom operations will take precedence over the EPSG ones.

Reprojection Console¶

The reprojection console (available in Demos) lets you quickly test coordinate operations. Use it to convert a single coordinate or WKT geometry, and to see the operation details GeoServer is using. It is also useful to learn by example when you have to Define a custom Coordinate Operation.

Read more about the Reprojection console.

Add Grid Shift Transform files¶

GeoServer supports NTv2 and NADCON grid shift transforms. Grid files are not shipped out with GeoServer. They need to be downloaded, usually from yor National Mapping Agency website.

Warning

Grid Shift files are only valid in the specific geographic domain for which they where made; trying to transform coordinates outside this domain will result in no trasformation at all. Make sure that the Grid Shift files are valid in the area you want to transform.

Search for the Grid File Name(s) int the tables below, which are extracted from EPSG version 7.9.0. If you need to use a Grid Shift transform not declared in EPSG, you will need to Define a custom Coordinate Operation.
Get the Grid File(s) from your National Mapping Agency (NTv2) or the US National Geodetic Survey (NADCON).
Copy the Grid File(s) in the user_projections directory inside your data directory.
Use the Reprojection Console to test the new transform.

List of available Grid Shift transforms¶

The list of Grid Shift transforms declared in EPSG version 7.9.0 is:

NTv2¶

Source CRS	Target CRS	Grid File Name	Source Info
4122	4326	NB7783v2.gsb	OGP
4122	4326	NS778301.gsb	OGP
4122	4326	PE7783V2.gsb	OGP
4122	4617	NB7783v2.gsb	New Brunswick Geographic Information Corporation land and water information standards manual.
4122	4617	NS778301.gsb	Nova Scotia Geomatics Centre - Contact aflemmin@linux1.nsgc.gov.ns.ca or telephone 902-667-6409
4122	4617	PE7783V2.gsb	PEI Department of Transportation & Public Works
4149	4150	CHENyx06a.gsb	Bundesamt für Landestopografie swisstopo; www.swisstopo.ch
4149	4151	CHENyx06_ETRS.gsb	Bundesamt für Landestopografie swisstopo; www.swisstopo.ch
4149	4258	CHENyx06_ETRS.gsb	Bundesamt für Landestopografie swisstopo; www.swisstopo.ch
4149	4326	CHENyx06_ETRS.gsb	IOGP
4171	4275	rgf93_ntf.gsb	ESRI
4202	4283	A66 National (13.09.01).gsb	GDA Technical Manual. http://www.icsm.gov.au/gda
4202	4283	SEAust_21_06_00.gsb	Office of Surveyor General Victoria; http://www.land.vic.gov.au/
4202	4283	nt_0599.gsb	GDA Technical Manual. http://www.icsm.gov.au/gda
4202	4283	tas_1098.gsb	http://www.delm.tas.gov.au/osg/Geodetic_transform.htm
4202	4283	vic_0799.gsb	Office of Surveyor General Victoria; http://www.land.vic.gov.au/
4202	4326	A66 National (13.09.01).gsb	OGP
4203	4283	National 84 (02.07.01).gsb	GDA Technical Manual. http://www.icsm.gov.au/gda
4203	4283	wa_0700.gsb	Department of Land Information, Government of Western Australia; http://www.dola.wa.gov.au/
4203	4326	National 84 (02.07.01).gsb	OGP
4207	4258	DLx_ETRS89_geo.gsb	Instituto Geografico Portugues; http://www.igeo.pt
4225	4326	CA7072_003.gsb	OGP
4225	4674	CA7072_003.gsb	IBGE.
4230	4258	100800401.gsb	Geodesy Unit, Cartographic Institute of Catalonia (ICC); http://www.icc.cat
4230	4258	SPED2ETV2.gsb	Instituto Geográfico Nacional, www.cnig.es
4230	4326	SPED2ETV2.gsb	OGP
4258	4275	rgf93_ntf.gsb	OGP
4267	4269	NTv2_0.gsb	http://www.geod.nrcan.gc.ca/products/html-public/GSDapps/English/NTv2_Fact_Sheet.html
4267	4269	QUE27-83.gsb	Geodetic Service of Quebec. Contact alain.bernard@mrn.gouv.qc.ca
4267	4326	NTv2_0.gsb	OGP
4267	4326	QUE27-98.gsb	OGP
4267	4326	SK27-98.gsb	OGP
4267	4617	NB2783v2.gsb	“Generation of a NAD27-NAD83(CSRS) NTv2-type Grid Shift File for New Brunswick”, Marcelo C. Santos and Carlos A. Garcia, Department of Geodesy and Geomatics Engineering, University of New Brunswick, October, 2011 via Service New Brunswick.
4267	4617	QUE27-98.gsb	Geodetic Service of Quebec. Contact alain.bernard@mrn.gouv.qc.ca
4267	4617	SK27-98.gsb	Dir Geodetic Surveys; SaskGeomatics Div.; Saskatchewan Property Management Company.
4269	4326	AB_CSRS.DAC	OGP
4269	4326	NAD83-98.gsb	OGP
4269	4326	SK83-98.gsb	OGP
4269	4617	AB_CSRS.DAC	Geodetic Control Section; Land and Forest Svc; Alberta Environment; http://www3.gov.ab.ca/env/land/dos/
4269	4617	NAD83-98.gsb	Geodetic Service of Quebec. Contact alain.bernard@mrn.gouv.qc.ca
4269	4617	SK83-98.gsb	Dir Geodetic Surveys; SaskGeomatics Div.; Saskatchewan Property Management Company.
4272	4167	nzgd2kgrid0005.gsb	Land Information New Zealand: LINZS25000 Standard for New Zealand Geodetic Datum 2000; 16 November 2007.
4272	4326	nzgd2kgrid0005.gsb	OGP
4274	4258	D73_ETRS89_geo.gsb	Instituto Geografico Portugues; http://www.igeo.pt
4277	4258	OSTN02_NTv2.gsb	Ordnance Survey of Great Britain, http://www.gps.gov.uk
4277	4258	OSTN15_NTv2_OSGBtoETRS.gsb	Ordnance Survey of Great Britain.
4277	4326	OSTN02_NTv2.gsb	OGP
4277	4326	OSTN15_NTv2_OSGBtoETRS.gsb	IOGP
4283	7844	COCOS_C_V1.gsb	GDA2020 Technical Manual (http://www.icsm.gov.au)
4283	7844	GDA94_GDA2020_conformal.gsb	GDA2020 Technical Manual and ICSM Datum Technical Fact Sheet TN1 (http://www.icsm.gov.au).
4283	7844	GDA94_GDA2020_conformal_and_distortion.gsb	GDA2020 Technical Manual and ICSM Datum Technical Fact Sheet TN1 (http://www.icsm.gov.au).
4283	7844	XMAS_C_V1.gsb	GDA2020 Technical Manual (http://www.icsm.gov.au).
4289	4258	rdtrans2008.gsb	Kadaster and Rijkswaterstaat CIV, working together under the name RDNAP.
4300	4258	tm75_etrs89.gsb	ESRI Ireland.
4300	4326	tm75_etrs89.gsb	OGP
4301	4612	tky2jgd.gsb	ESRI
4301	6668	tky2jgd.gsb	OGP
4312	4258	AT_GIS_GRID.gsb	Federal Office of Metrology and Surveying (BEV); http://www.bev.gv.at
4313	4258	bd72lb72_etrs89lb08.gsb	IGN Brussels www.ngi.be
4314	4258	BETA2007.gsb	BKG via EuroGeographics http://crs.bkg.bund.de/crs-eu/
4314	4326	BETA2007.gsb	OGP
4326	4275	rgf93_ntf.gsb	OGP
4608	4269	May76v20.gsb	Geodetic Survey of Canada http://www.geod.nrcan.gc.ca/
4608	4326	May76v20.gsb	OGP
4609	4269	CGQ77-83.gsb	Geodetic Service of Quebec. Contact alain.bernard@mrn.gouv.qc.ca
4609	4326	CGQ77-98.gsb	OGP
4609	4617	CGQ77-98.gsb	Geodetic Service of Quebec. Contact alain.bernard@mrn.gouv.qc.ca
4612	6668	touhokutaiheiyouoki2011.gsb	ESRI
4618	4326	SAD69_003.gsb	OGP
4618	4674	SAD69_003.gsb	IBGE.
4745	4258	NTv2_SN.gsb	Saxony State Spatial Data and Land Survey Corporation (GeoSN).
4745	4326	BETA2007.gsb	OGP
4746	4326	BETA2007.gsb	OGP
4749	4644	RGNC1991_NEA74Noumea.gsb	ESRI
4749	4662	RGNC1991_IGN72GrandeTerre.gsb	ESRI
5524	4326	CA61_003.gsb	OGP
5524	4674	CA61_003.gsb	IBGE.
5527	4326	SAD96_003.gsb	OGP
5527	4674	SAD96_003.gsb	IBGE.

NADCON¶

Source CRS	Target CRS	Version	Latitude shift file	Longitude shift file
4135	4269	NGS-Usa HI	hawaii.las	hawaii.los
4136	4269	NGS-Usa AK StL	stlrnc.las	stlrnc.los
4137	4269	NGS-Usa AK StP	stpaul.las	stpaul.los
4138	4269	NGS-Usa AK StG	stgeorge.las	stgeorge.los
4139	4269	NGS-PRVI	prvi.las	prvi.los
4169	4152	NGS-Asm E	eshpgn.las	eshpgn.los
4169	4152	NGS-Asm W	wshpgn.las	wshpgn.los
4267	4269	NGS-Usa AK	alaska.las	alaska.los
4267	4269	NGS-Usa Conus	conus.las	conus.los
4269	4152	NGS-Usa AL	alhpgn.las	alhpgn.los
4269	4152	NGS-Usa AR	arhpgn.las	arhpgn.los
4269	4152	NGS-Usa AZ	azhpgn.las	azhpgn.los
4269	4152	NGS-Usa CA n	cnhpgn.las	cnhpgn.los
4269	4152	NGS-Usa CO	cohpgn.las	cohpgn.los
4269	4152	NGS-Usa CA s	cshpgn.las	cshpgn.los
4269	4152	NGS-Usa ID MT e	emhpgn.las	emhpgn.los
4269	4152	NGS-Usa TX e	ethpgn.las	ethpgn.los
4269	4152	NGS-Usa FL	flhpgn.las	flhpgn.los
4269	4152	NGS-Usa GA	gahpgn.las	gahpgn.los
4269	4152	NGS-Usa HI	hihpgn.las	hihpgn.los
4269	4152	NGS-Usa IA	iahpgn.las	iahpgn.los
4269	4152	NGS-Usa IL	ilhpgn.las	ilhpgn.los
4269	4152	NGS-Usa IN	inhpgn.las	inhpgn.los
4269	4152	NGS-Usa KS	kshpgn.las	kshpgn.los
4269	4152	NGS-Usa KY	kyhpgn.las	kyhpgn.los
4269	4152	NGS-Usa LA	lahpgn.las	lahpgn.los
4269	4152	NGS-Usa DE MD	mdhpgn.las	mdhpgn.los
4269	4152	NGS-Usa ME	mehpgn.las	mehpgn.los
4269	4152	NGS-Usa MI	mihpgn.las	mihpgn.los
4269	4152	NGS-Usa MN	mnhpgn.las	mnhpgn.los
4269	4152	NGS-Usa MO	mohpgn.las	mohpgn.los
4269	4152	NGS-Usa MS	mshpgn.las	mshpgn.los
4269	4152	NGS-Usa NE	nbhpgn.las	nbhpgn.los
4269	4152	NGS-Usa NC	nchpgn.las	nchpgn.los
4269	4152	NGS-Usa ND	ndhpgn.las	ndhpgn.los
4269	4152	NGS-Usa NewEng	nehpgn.las	nehpgn.los
4269	4152	NGS-Usa NJ	njhpgn.las	njhpgn.los
4269	4152	NGS-Usa NM	nmhpgn.las	nmhpgn.los
4269	4152	NGS-Usa NV	nvhpgn.las	nvhpgn.los
4269	4152	NGS-Usa NY	nyhpgn.las	nyhpgn.los
4269	4152	NGS-Usa OH	ohhpgn.las	ohhpgn.los
4269	4152	NGS-Usa OK	okhpgn.las	okhpgn.los
4269	4152	NGS-Usa PA	pahpgn.las	pahpgn.los
4269	4152	NGS-PRVI	pvhpgn.las	pvhpgn.los
4269	4152	NGS-Usa SC	schpgn.las	schpgn.los
4269	4152	NGS-Usa SD	sdhpgn.las	sdhpgn.los
4269	4152	NGS-Usa TN	tnhpgn.las	tnhpgn.los
4269	4152	NGS-Usa UT	uthpgn.las	uthpgn.los
4269	4152	NGS-Usa VA	vahpgn.las	vahpgn.los
4269	4152	NGS-Usa WI	wihpgn.las	wihpgn.los
4269	4152	NGS-Usa ID MT w	wmhpgn.las	wmhpgn.los
4269	4152	NGS-Usa OR WA	wohpgn.las	wohpgn.los
4269	4152	NGS-Usa TX w	wthpgn.las	wthpgn.los
4269	4152	NGS-Usa WV	wvhpgn.las	wvhpgn.los
4269	4152	NGS-Usa WY	wyhpgn.las	wyhpgn.los
4675	4152	NGS-Gum	guhpgn.las	guhpgn.los
8351	4156	UGKK-Svk	Slovakia_JTSK03_to_JTSK.LAS.las	Slovakia_JTSK03_to_JTSK.LAS.los
8351	4156	UGKK-Svk	Slovakia_JTSK03_to_JTSK.LOS.las	Slovakia_JTSK03_to_JTSK.LOS.los

Define a custom Coordinate Operation¶

Custom Coordinate Operations are defined in epsg_operations.properties file. This file has to be placed into the user_projections directory, inside your data directory (create it if it doesn’t exist).

Each line in epsg_operations.properties will describe a coordinate operation consisting of a source CRS, a target CRS, and a math transform with its parameter values. Use the following syntax:

<source crs code>,<target crs code>=<WKT math transform>

Math transform is described in Well-Known Text syntax. Parameter names and value ranges are described in the EPSG Geodetic Parameter Registry.

Note

Use the Reprojection Console to learn from example and to test your custom definitions.

Examples¶

Custom NTv2 file:

4230,4258=PARAM_MT["NTv2", \
  PARAMETER["Latitude and longitude difference file", "100800401.gsb"]]

Geocentric transformation, preceded by an ellipsoid to geocentric conversion, and back geocentric to ellipsoid. The results is a concatenation of three math transforms:

4230,4258=CONCAT_MT[ \
  PARAM_MT["Ellipsoid_To_Geocentric", \
    PARAMETER["dim", 2], \
    PARAMETER["semi_major", 6378388.0], \
    PARAMETER["semi_minor", 6356911.9461279465]], \
  PARAM_MT["Position Vector transformation (geog2D domain)", \
    PARAMETER["dx", -116.641], \
    PARAMETER["dy", -56.931], \
    PARAMETER["dz", -110.559], \
    PARAMETER["ex", 0.8925078166311858], \
    PARAMETER["ey", 0.9207660950870382], \
    PARAMETER["ez", -0.9166407989620964], \
    PARAMETER["ppm", -3.5200000000346066]], \
  PARAM_MT["Geocentric_To_Ellipsoid", \
    PARAMETER["dim", 2], \
    PARAMETER["semi_major", 6378137.0], \
    PARAMETER["semi_minor", 6356752.314140356]]]

You can make use of existing grid shift files such as this explicit transformation from NAD27 to WGS84 made up of a NADCON transform from NAD27 to NAD83 followed by a Molodenski transform converting from the GRS80 Ellipsoid (used by NAD83) to the WGS84 Ellipsoid:

4267,4326=CONCAT_MT[ \
  PARAM_MT["NADCON", \
    PARAMETER["Latitude difference file", "conus.las"], \
    PARAMETER["Longitude difference file", "conus.los"]], \
  PARAM_MT["Molodenski", \
    PARAMETER["dim", 2], \
    PARAMETER["dx", 0.0], \
    PARAMETER["dy", 0.0], \
    PARAMETER["dz", 0.0], \
    PARAMETER["src_semi_major", 6378137.0], \
    PARAMETER["src_semi_minor", 6356752.314140356], \
    PARAMETER["tgt_semi_major", 6378137.0], \
    PARAMETER["tgt_semi_minor", 6356752.314245179]]]

Affine 2D transform operating directly in projected coordinates:

23031,25831=PARAM_MT["Affine", \
  PARAMETER["num_row", 3], \
  PARAMETER["num_col", 3], \
  PARAMETER["elt_0_0", 1.0000015503712145], \
  PARAMETER["elt_0_1", 0.00000758753979846734], \
  PARAMETER["elt_0_2", -129.549], \
  PARAMETER["elt_1_0", -0.00000758753979846734], \
  PARAMETER["elt_1_1", 1.0000015503712145], \
  PARAMETER["elt_1_2", -208.185]]

Each operation can be described in a single line, or can be split in several lines for readability, adding a backslash “" at the end of each line, as in the former examples.

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