EPSG Dataset :: v12.003

NADCON

Coordinate Operation Method Details [VALID]

Name:

NADCON

Code:

9613

Operation is Reversible:

Yes

Formula:

The latitude and longitude offsets at a point are derived by interpolation within the gridded data. Separate grid files are given for latitude and longitude offsets. The grid file format is given in documentation available from the information source. Bi-linear interpolation is used to derive the offset values. For the forward calculation the interpolated value of the offset is then added to the source CRS coordinate value to give the coordinates in the target CRS.

Reversibility
Iteration is required for the reverse transformation. The coordinate reference system for the coordinates of the grid nodes is the source coordinate reference system for the forward transformation. Then in forward transformations the offset is obtained through straightforward interpolation of the grid file. But for the reverse transformation the first grid interpolation entry will be the value of the point in the second coordinate reference system, the offsets are interpolated and applied with sign reversed, and the result used in further iterations of interpolation and application of offset until the difference between results from successive iterations is insignificant.

Example:

(none)

Method
Parameters:

Parameter Name	Parameter Code	Sign reversal	Parameter Description
Latitude difference file	8657	Yes	The name of the [path and] file containing latitude differences.
Longitude difference file	8658	Yes	The name of the [path and] file containing longitude differences.

Meta Data

Remarks:

Geodetic transformation operating on geographic coordinate differences by bi-linear interpolation. Input expects longitudes to be positive west.

Information Source:

US Coast and geodetic Survey - http://www.ngs.noaa.gov

Data Source:

EPSG

Revision Date:

June 13, 2017

Change ID:

[2004.19] [2008.027] [2017.018]

Wildcard	Example
% or *	Any wildcard characters
? or _	One wildcard character
[ - ]	[ - ] Range e.g. N[a-c] will return all geodetic objects that contains a string starting with the letter 'N' or 'n' followed by any of the letters contained within the range specified within the square bracket, e.g. letters a, b and c.
\|	Or e.g. E[a\|e]M will return all geodetic objects that contains a string starting with the letter E(e), ends with the letter M(m) and also contain either the letter a or letter e.