EPSG:19911

Laborde Grid approximation

Attributes

Data source: EPSG

Information source: OGP

Revision date: 2007-01-11

Scope: Topographic mapping (medium scale).

Remarks: Longitude is referenced to the Paris meridian. The conversion method is a good approximation (better than 5cm) to original formula (see proj code 19861) within a few hundred km of origin, but farther away the approximation may be no better than 1m.

Method: Hotine Oblique Mercator (variant B)

Area of use: Madagascar - onshore and nearshore.

Description: (0,)

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Madagascar - onshore and nearshore.

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Definition: OGC Well Known Text

PROJECTION["Hotine_Oblique_Mercator_Azimuth_Center"],
PARAMETER["latitude_of_center",-18.9],
PARAMETER["longitude_of_center",44.1],
PARAMETER["azimuth",18.9],
PARAMETER["rectified_grid_angle",18.9],
PARAMETER["scale_factor",0.9995],
PARAMETER["false_easting",400000],
PARAMETER["false_northing",800000]

Definition: OGC Well Known Text 2 (2019)

CONVERSION["Laborde Grid approximation",
    METHOD["Hotine Oblique Mercator (variant B)",
        ID["EPSG",9815]],
    PARAMETER["Latitude of projection centre",-21,
        ANGLEUNIT["grad",0.0157079632679489],
        ID["EPSG",8811]],
    PARAMETER["Longitude of projection centre",49,
        ANGLEUNIT["grad",0.0157079632679489],
        ID["EPSG",8812]],
    PARAMETER["Azimuth of initial line",21,
        ANGLEUNIT["grad",0.0157079632679489],
        ID["EPSG",8813]],
    PARAMETER["Angle from Rectified to Skew Grid",21,
        ANGLEUNIT["grad",0.0157079632679489],
        ID["EPSG",8814]],
    PARAMETER["Scale factor on initial line",0.9995,
        SCALEUNIT["unity",1],
        ID["EPSG",8815]],
    PARAMETER["Easting at projection centre",400000,
        LENGTHUNIT["metre",1],
        ID["EPSG",8816]],
    PARAMETER["Northing at projection centre",800000,
        LENGTHUNIT["metre",1],
        ID["EPSG",8817]],
    ID["EPSG",19911]]

Definition: ESRI Well Known Text

PROJECTION["Hotine_Oblique_Mercator_Azimuth_Center"],
PARAMETER["False_Easting",400000.0],
PARAMETER["False_Northing",800000.0],
PARAMETER["Scale_Factor",0.9995],
PARAMETER["Azimuth",18.9],
PARAMETER["Longitude_Of_Center",44.1],
PARAMETER["Latitude_Of_Center",-18.9]

Definition: PROJ.4

+proj=omerc +lat_0=-18.9 +lonc=44.1 +alpha=18.9 +gamma=18.9 +k=0.9995 +x_0=400000 +y_0=800000

Definition: JavaScript (Proj4js) 

proj4.defs("EPSG:19911","+proj=omerc +lat_0=-18.9 +lonc=44.1 +alpha=18.9 +gamma=18.9 +k=0.9995 +x_0=400000 +y_0=800000");

Definition: JSON

{
    "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json",
    "type": "Conversion",
    "name": "Laborde Grid approximation",
    "method": {
        "name": "Hotine Oblique Mercator (variant B)",
        "id": {
            "authority": "EPSG",
            "code": 9815
        }
    },
    "parameters": [
        {
            "name": "Latitude of projection centre",
            "value": -21,
            "unit": {
                "type": "AngularUnit",
                "name": "grad",
                "conversion_factor": 0.0157079632679489
            },
            "id": {
                "authority": "EPSG",
                "code": 8811
            }
        },
        {
            "name": "Longitude of projection centre",
            "value": 49,
            "unit": {
                "type": "AngularUnit",
                "name": "grad",
                "conversion_factor": 0.0157079632679489
            },
            "id": {
                "authority": "EPSG",
                "code": 8812
            }
        },
        {
            "name": "Azimuth of initial line",
            "value": 21,
            "unit": {
                "type": "AngularUnit",
                "name": "grad",
                "conversion_factor": 0.0157079632679489
            },
            "id": {
                "authority": "EPSG",
                "code": 8813
            }
        },
        {
            "name": "Angle from Rectified to Skew Grid",
            "value": 21,
            "unit": {
                "type": "AngularUnit",
                "name": "grad",
                "conversion_factor": 0.0157079632679489
            },
            "id": {
                "authority": "EPSG",
                "code": 8814
            }
        },
        {
            "name": "Scale factor on initial line",
            "value": 0.9995,
            "unit": "unity",
            "id": {
                "authority": "EPSG",
                "code": 8815
            }
        },
        {
            "name": "Easting at projection centre",
            "value": 400000,
            "unit": "metre",
            "id": {
                "authority": "EPSG",
                "code": 8816
            }
        },
        {
            "name": "Northing at projection centre",
            "value": 800000,
            "unit": "metre",
            "id": {
                "authority": "EPSG",
                "code": 8817
            }
        }
    ],
    "id": {
        "authority": "EPSG",
        "code": 19911
    }
}

Definition: GeoServer

19911=PROJECTION["Hotine_Oblique_Mercator_Azimuth_Center"],PARAMETER["latitude_of_center",-18.9],PARAMETER["longitude_of_center",44.1],PARAMETER["azimuth",18.9],PARAMETER["rectified_grid_angle",18.9],PARAMETER["scale_factor",0.9995],PARAMETER["false_easting",400000],PARAMETER["false_northing",800000]

Definition: MapServer - MAPfile

PROJECTION
	"proj=omerc"
	"lat_0=-18.9"
	"lonc=44.1"
	"alpha=18.9"
	"gamma=18.9"
	"k=0.9995"
	"x_0=400000"
	"y_0=800000"
END

Definition: Mapnik

<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=omerc +lat_0=-18.9 +lonc=44.1 +alpha=18.9 +gamma=18.9 +k=0.9995 +x_0=400000 +y_0=800000">
	<Layer srs="+proj=omerc +lat_0=-18.9 +lonc=44.1 +alpha=18.9 +gamma=18.9 +k=0.9995 +x_0=400000 +y_0=800000">
	</Layer>
</Map>

Definition: SQL (PostGIS)

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 19911, 'EPSG', 19911, '+proj=omerc +lat_0=-18.9 +lonc=44.1 +alpha=18.9 +gamma=18.9 +k=0.9995 +x_0=400000 +y_0=800000', 'PROJECTION["Hotine_Oblique_Mercator_Azimuth_Center"],PARAMETER["latitude_of_center",-18.9],PARAMETER["longitude_of_center",44.1],PARAMETER["azimuth",18.9],PARAMETER["rectified_grid_angle",18.9],PARAMETER["scale_factor",0.9995],PARAMETER["false_easting",400000],PARAMETER["false_northing",800000]');