org.geotoolkit.referencing.operation.transform
Class NadconTransform

Object
  FormattableObject
      AbstractMathTransform
          GridTransform
              GridTransform2D
                  NadconTransform

All Implemented Interfaces:

Serializable, Formattable, Parameterized, LenientComparable, MathTransform, MathTransform2D

@Immutable
public class NadconTransform
extends GridTransform2D

The NADCON transform (EPSG code 9613). See North American Datum Conversion Utility for an overview. See any of the following providers for a list of programmatic parameters:

• NADCON

Description
NADCON is a two dimentional datum shift method, created by the National Geodetic Survey (NGS), that uses interpolated values from two grid shift files. This method is used to transform NAD27 (EPSG:4267) datum coordinates (and some others) to NAD83 (EPSG:4269) within the United States.

There are two set of grid shift files: NADCON and High Accuracy Reference Networks (HARN). NADCON shifts from NAD27 (and some others) to NAD83 while HARN shifts from the NADCON NAD83 to an improved NAD83. Both sets of grid shift files may be downloaded from www.ngs.noaa.gov/PC_PROD/NADCON/. The geotk-setup module can download the data and install them in a directory where they can be find automatically.

Some of the NADCON grids, their areas of use, and source datums are shown in the following table. The accuracy column is in metres at 67% confidence.

File Name	Area	Source Datum	Accuracy
CONUS	Conterminous U S (lower 48 states)	NAD27	0.15
ALASKA	Alaska, incl. Aleutian Islands	NAD27	0.5
HAWAII	Hawaiian Islands	Old Hawaiian (4135)	0.2
STLRNC	St. Lawrence Is., AK	St. Lawrence Island (4136)	-
STPAUL	St. Paul Is., AK	St. Paul Island (4137)	-
STGEORGE	St. George Is., AK	St. George Island (4138)	-
PRVI	Puerto Rico and the Virgin Islands	Puerto Rico (4139)	0.05

The grid names to use for transforming are parameters of this MathTransform. Those parameters may be the full name and path to the grids or just the name of the grids if the default location of the grids was set as a preference. This preference may be set with the above-cited geotk-setup module.

Transformations here have been tested to be within 0.00001 seconds of values given by the NGS ndcon210 program for NADCON grids. American Samoa and HARN shifts have not yet been tested.

References

• NADCON Readme
• American Samoa Grids for NADCON - Samoa Readme.txt
• NADCON - The Application of Minimum-Curvature-Derived Surfaces in the Transformation of Positional Data From the North American Datum of 1927 to the North American Datum of 1983 - NOAA TM.
• ndcon210.for - NGS fortran source code for NADCON conversions. See the following subroutines: TRANSF, TO83, FGRID, INTRP, COEFF and SURF
• nadgrd.for - NGS fortran source code to export/import binary and text grid formats
• EPSG Geodesy Parameters database

Since:

2.1

Version:

3.03

Author:

Rueben Schulz (UBC), Martin Desruisseaux (Geomatys)

See Also:

Serialized Form

Module:

referencing/geotk-referencing (download)

View source code for this class

Field Summary

Fields inherited from class GridTransform

grid, height, width

Fields inherited from class FormattableObject

EPSG, GEOTIFF, INTERNAL, OGC, SINGLE_LINE

Constructor Summary

NadconTransform(String longitudeGridFile, String latitudeGridFile)
Constructs a grid from the specified shift files.

Method Summary

ParameterDescriptorGroup	getParameterDescriptors() Returns the parameter descriptors for this math transform.
ParameterValueGroup	getParameterValues() Returns the parameter values for this math transform.

Methods inherited from class GridTransform2D

derivative, inverse

Methods inherited from class GridTransform

computeHashCode, create, create, create, derivative, equals, getSourceDimensions, getTargetDimensions, isIdentity, transform, transform, transform, transform, transform

Methods inherited from class AbstractMathTransform

createTransformedShape, ensureNonNull, equals, formatWKT, getName, hashCode, rollLongitude, transform, transform

Methods inherited from class FormattableObject

getDefaultIndentation, print, setDefaultIndentation, toString, toWKT, toWKT, toWKT

Methods inherited from class Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface MathTransform2D

createTransformedShape, transform

Methods inherited from interface MathTransform

derivative, getSourceDimensions, getTargetDimensions, isIdentity, toWKT, transform, transform, transform, transform, transform

Constructor Detail

NadconTransform

public NadconTransform(String longitudeGridFile,
                       String latitudeGridFile)
                throws FactoryException

Constructs a grid from the specified shift files. The arguments may be file paths and names, or just file names. They are resolved as below:

• If an argument is a URL or absolute file, then it is used directly.
• Otherwise if an argument is a single filename with no parent directory, and if the file is found in a org/geotoolkit/referencing/operation/transform/NADCON directory on the classpath, then that later file is used.
• Otherwise (i.e. the file is relative and not presents on the classpath), prepend the grid location set by the user, if any. This location can be set by the geotk-setup module, which can also download and install the data.

Parameters:

longitudeGridFile - Path (optional) and name to the longitude difference file. This will have a ".los" or ".loa" file extention.

latitudeGridFile - Path (optional) and name to the latitude difference file. This will have a ".las" or ".laa" file extention.

Throws:

FactoryException - If there is an error reading the grid files.

Method Detail

getParameterDescriptors

public ParameterDescriptorGroup getParameterDescriptors()

Returns the parameter descriptors for this math transform.

Specified by:

getParameterDescriptors in interface Parameterized

Overrides:

getParameterDescriptors in class AbstractMathTransform

Returns:

The parameter descriptors for this math transform, or null.

See Also:

OperationMethod.getParameters()

getParameterValues

public ParameterValueGroup getParameterValues()

Returns the parameter values for this math transform.

Specified by:

getParameterValues in interface Parameterized

Overrides:

getParameterValues in class AbstractMathTransform

Returns:

A copy of the parameter values for this math transform, or null. Since this method returns a copy of the parameter values, any change to a value will have no effect on this math transform.

See Also:

SingleOperation.getParameterValues()