EPSG:7974

NGVD29 height (ftUS) to NAVD88 height (2)

Attributes

Geodetic CRS: NGVD29 height (ftUS)

Datum: National Geodetic Vertical Datum 1929

Data source: EPSG

Information source: IOGP

Revision date: 2021-04-20

Steps of transformation: 7813 7970

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Definition: OGC Well Known Text 2 (2019)

CONCATENATEDOPERATION["NGVD29 height (ftUS) to NAVD88 height (2)",
    VERSION["IOGP - US Conus C"],
    SOURCECRS[
        VERTCRS["NGVD29 height (ftUS)",
            VDATUM["National Geodetic Vertical Datum 1929"],
            CS[vertical,1],
                AXIS["gravity-related height (H)",up,
                    LENGTHUNIT["US survey foot",0.304800609601219]],
            ID["EPSG",5702]]],
    TARGETCRS[
        VERTCRS["NAVD88 height",
            VDATUM["North American Vertical Datum 1988"],
            CS[vertical,1],
                AXIS["gravity-related height (H)",up,
                    LENGTHUNIT["metre",1]],
            ID["EPSG",5703]]],
    STEP[
        CONVERSION["Vertical Axis Unit Conversion",
            METHOD["Change of Vertical Unit",
                ID["EPSG",1104]],
            ID["EPSG",7813]]],
    STEP[
        COORDINATEOPERATION["NGVD29 height (m) to NAVD88 height (2)",
            VERSION["NGS-US Conus C"],
            SOURCECRS[
                VERTCRS["NGVD29 height (m)",
                    VDATUM["National Geodetic Vertical Datum 1929"],
                    CS[vertical,1],
                        AXIS["gravity-related height (H)",up,
                            LENGTHUNIT["metre",1]],
                    ID["EPSG",7968]]],
            TARGETCRS[
                VERTCRS["NAVD88 height",
                    VDATUM["North American Vertical Datum 1988"],
                    CS[vertical,1],
                        AXIS["gravity-related height (H)",up,
                            LENGTHUNIT["metre",1]],
                    ID["EPSG",5703]]],
            METHOD["Vertical Offset by Grid Interpolation (VERTCON)",
                ID["EPSG",9658]],
            PARAMETERFILE["Vertical offset file","vertconc.94"],
            OPERATIONACCURACY[0.02],
            ID["EPSG",7970],
            REMARK["In the SE of this area the NGVD29 surface is 0 to 0.1m above the NAVD88 surface; in the W it is 0.6 to 0.9m below the NAVD88 surface. Interpolation in the data file may be made using either NAD27 or any of the NAD83 realizations applicable to US conus."]]],
    OPERATIONACCURACY[0.02],
    USAGE[
        SCOPE["Change of height to a different vertical reference surface and unit."],
        AREA["United States (USA) - CONUS between 89°W and 107°W - onshore - Arkansas; Colorado; Illinois; Iowa; Kansas; Louisiana; Michigan; Minnesota; Mississippi; Missouri; Montana; Nebraska; New Mexico; North Dakota; Oklahoma; South Dakota; Tennessee; Texas; Wisconsin; Wyoming."],
        BBOX[25.83,-107,49.38,-89]],
    ID["EPSG",7974]]

Definition: PROJ.4

+proj=pipeline +step +proj=unitconvert +z_in=us-ft +z_out=m +step +proj=vgridshift +grids=us_noaa_vertconc.tif +multiplier=1

Definition: JavaScript (Proj4js)

proj4.defs("EPSG:7974","+proj=pipeline +step +proj=unitconvert +z_in=us-ft +z_out=m +step +proj=vgridshift +grids=us_noaa_vertconc.tif +multiplier=1");

Definition: JSON

{
    "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json",
    "type": "ConcatenatedOperation",
    "name": "NGVD29 height (ftUS) to NAVD88 height (2)",
    "source_crs": {
        "type": "VerticalCRS",
        "name": "NGVD29 height (ftUS)",
        "datum": {
            "type": "VerticalReferenceFrame",
            "name": "National Geodetic Vertical Datum 1929"
        },
        "coordinate_system": {
            "subtype": "vertical",
            "axis": [
                {
                    "name": "Gravity-related height",
                    "abbreviation": "H",
                    "direction": "up",
                    "unit": {
                        "type": "LinearUnit",
                        "name": "US survey foot",
                        "conversion_factor": 0.304800609601219
                    }
                }
            ]
        },
        "id": {
            "authority": "EPSG",
            "code": 5702
        }
    },
    "target_crs": {
        "type": "VerticalCRS",
        "name": "NAVD88 height",
        "datum": {
            "type": "VerticalReferenceFrame",
            "name": "North American Vertical Datum 1988"
        },
        "coordinate_system": {
            "subtype": "vertical",
            "axis": [
                {
                    "name": "Gravity-related height",
                    "abbreviation": "H",
                    "direction": "up",
                    "unit": "metre"
                }
            ]
        },
        "id": {
            "authority": "EPSG",
            "code": 5703
        }
    },
    "steps": [
        {
            "type": "Conversion",
            "name": "Vertical Axis Unit Conversion",
            "method": {
                "name": "Change of Vertical Unit",
                "id": {
                    "authority": "EPSG",
                    "code": 1104
                }
            },
            "id": {
                "authority": "EPSG",
                "code": 7813
            }
        },
        {
            "type": "Transformation",
            "name": "NGVD29 height (m) to NAVD88 height (2)",
            "source_crs": {
                "type": "VerticalCRS",
                "name": "NGVD29 height (m)",
                "datum": {
                    "type": "VerticalReferenceFrame",
                    "name": "National Geodetic Vertical Datum 1929"
                },
                "coordinate_system": {
                    "subtype": "vertical",
                    "axis": [
                        {
                            "name": "Gravity-related height",
                            "abbreviation": "H",
                            "direction": "up",
                            "unit": "metre"
                        }
                    ]
                },
                "id": {
                    "authority": "EPSG",
                    "code": 7968
                }
            },
            "target_crs": {
                "type": "VerticalCRS",
                "name": "NAVD88 height",
                "datum": {
                    "type": "VerticalReferenceFrame",
                    "name": "North American Vertical Datum 1988"
                },
                "coordinate_system": {
                    "subtype": "vertical",
                    "axis": [
                        {
                            "name": "Gravity-related height",
                            "abbreviation": "H",
                            "direction": "up",
                            "unit": "metre"
                        }
                    ]
                },
                "id": {
                    "authority": "EPSG",
                    "code": 5703
                }
            },
            "method": {
                "name": "Vertical Offset by Grid Interpolation (VERTCON)",
                "id": {
                    "authority": "EPSG",
                    "code": 9658
                }
            },
            "parameters": [
                {
                    "name": "Vertical offset file",
                    "value": "vertconc.94",
                    "id": {
                        "authority": "EPSG",
                        "code": 8732
                    }
                }
            ],
            "accuracy": "0.02",
            "id": {
                "authority": "EPSG",
                "code": 7970
            },
            "remarks": "In the SE of this area the NGVD29 surface is 0 to 0.1m above the NAVD88 surface; in the W it is 0.6 to 0.9m below the NAVD88 surface. Interpolation in the data file may be made using either NAD27 or any of the NAD83 realizations applicable to US conus."
        }
    ],
    "accuracy": "0.02",
    "scope": "Change of height to a different vertical reference surface and unit.",
    "area": "United States (USA) - CONUS between 89°W and 107°W - onshore - Arkansas; Colorado; Illinois; Iowa; Kansas; Louisiana; Michigan; Minnesota; Mississippi; Missouri; Montana; Nebraska; New Mexico; North Dakota; Oklahoma; South Dakota; Tennessee; Texas; Wisconsin; Wyoming.",
    "bbox": {
        "south_latitude": 25.83,
        "west_longitude": -107,
        "north_latitude": 49.38,
        "east_longitude": -89
    },
    "id": {
        "authority": "EPSG",
        "code": 7974
    }
}

Definition: MapServer - MAPfile

PROJECTION
	"proj=pipeline"
	"step"
	"proj=unitconvert"
	"z_in=us-ft"
	"z_out=m"
	"step"
	"proj=vgridshift"
	"grids=us_noaa_vertconc.tif"
	"multiplier=1"
END

Definition: Mapnik

<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=pipeline +step +proj=unitconvert +z_in=us-ft +z_out=m +step +proj=vgridshift +grids=us_noaa_vertconc.tif +multiplier=1">
	<Layer srs="+proj=pipeline +step +proj=unitconvert +z_in=us-ft +z_out=m +step +proj=vgridshift +grids=us_noaa_vertconc.tif +multiplier=1">
	</Layer>
</Map>

Definition: SQL (PostGIS)

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 7974, 'EPSG', 7974, '+proj=pipeline +step +proj=unitconvert +z_in=us-ft +z_out=m +step +proj=vgridshift +grids=us_noaa_vertconc.tif +multiplier=1', 'None');