EPSG:7977

HKPD depth to HKCD depth (1)

Attributes

Geodetic CRS: HKPD height

Datum: Hong Kong Principal Datum

Data source: EPSG

Information source: Survey and Mapping Office, Lands Department. Http://www.info.gov.hk/landsd/mapping/tindex.htm

Revision date: 2017-10-16

Scope: Change of depth to a different vertical reference surface.

Remarks: The HKPD vertical reference surface is 0.146m above the HKCD surface.

Method: Vertical Offset

Area of use: China - Hong Kong - offshore.

Description: (0,)

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China - Hong Kong - offshore.

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Definition: OGC Well Known Text 2 (2019)

COORDINATEOPERATION["HKPD depth to HKCD depth (1)",
    VERSION["SMO-HK"],
    SOURCECRS[
        VERTCRS["HKPD depth",
            VDATUM["Hong Kong Principal Datum"],
            CS[vertical,1],
                AXIS["depth (D)",down,
                    LENGTHUNIT["metre",1]],
            ID["EPSG",7976]]],
    TARGETCRS[
        VERTCRS["HKCD depth",
            VDATUM["Hong Kong Chart Datum"],
            CS[vertical,1],
                AXIS["depth (D)",down,
                    LENGTHUNIT["metre",1]],
            ID["EPSG",5739]]],
    METHOD["Vertical Offset",
        ID["EPSG",9616]],
    PARAMETER["Vertical Offset",-0.146,
        LENGTHUNIT["metre",1],
        ID["EPSG",8603]],
    OPERATIONACCURACY[0.0],
    USAGE[
        SCOPE["Change of depth to a different vertical reference surface."],
        AREA["China - Hong Kong - offshore."],
        BBOX[22.13,113.76,22.58,114.51]],
    ID["EPSG",7977],
    REMARK["The HKPD vertical reference surface is 0.146m above the HKCD surface."]]

Definition: PROJ.4

+proj=geogoffset +dh=-0.146

Definition: JavaScript (Proj4js) 

proj4.defs("EPSG:7977","+proj=geogoffset +dh=-0.146");

Definition: JSON

{
    "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json",
    "type": "Transformation",
    "name": "HKPD depth to HKCD depth (1)",
    "source_crs": {
        "type": "VerticalCRS",
        "name": "HKPD depth",
        "datum": {
            "type": "VerticalReferenceFrame",
            "name": "Hong Kong Principal Datum"
        },
        "coordinate_system": {
            "subtype": "vertical",
            "axis": [
                {
                    "name": "Depth",
                    "abbreviation": "D",
                    "direction": "down",
                    "unit": "metre"
                }
            ]
        },
        "id": {
            "authority": "EPSG",
            "code": 7976
        }
    },
    "target_crs": {
        "type": "VerticalCRS",
        "name": "HKCD depth",
        "datum": {
            "type": "VerticalReferenceFrame",
            "name": "Hong Kong Chart Datum"
        },
        "coordinate_system": {
            "subtype": "vertical",
            "axis": [
                {
                    "name": "Depth",
                    "abbreviation": "D",
                    "direction": "down",
                    "unit": "metre"
                }
            ]
        },
        "id": {
            "authority": "EPSG",
            "code": 5739
        }
    },
    "method": {
        "name": "Vertical Offset",
        "id": {
            "authority": "EPSG",
            "code": 9616
        }
    },
    "parameters": [
        {
            "name": "Vertical Offset",
            "value": -0.146,
            "unit": "metre",
            "id": {
                "authority": "EPSG",
                "code": 8603
            }
        }
    ],
    "accuracy": "0.0",
    "scope": "Change of depth to a different vertical reference surface.",
    "area": "China - Hong Kong - offshore.",
    "bbox": {
        "south_latitude": 22.13,
        "west_longitude": 113.76,
        "north_latitude": 22.58,
        "east_longitude": 114.51
    },
    "id": {
        "authority": "EPSG",
        "code": 7977
    },
    "remarks": "The HKPD vertical reference surface is 0.146m above the HKCD surface."
}

Definition: MapServer - MAPfile

PROJECTION
	"proj=geogoffset"
	"dh=-0.146"
END

Definition: Mapnik

<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=geogoffset +dh=-0.146">
	<Layer srs="+proj=geogoffset +dh=-0.146">
	</Layer>
</Map>

Definition: SQL (PostGIS)

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 7977, 'EPSG', 7977, '+proj=geogoffset +dh=-0.146', 'None');