Object
- Formattable
- - AbstractMathTransform
  - - NADCONTransform

All Implemented Interfaces:: Serializable, MathTransform, MathTransform2D

public class NADCONTransform
extends AbstractMathTransform
implements MathTransform2D, Serializable

Transform backed by the North American Datum Conversion grid. The North American Datum Conversion (NADCON) Transform (EPSG code 9613) 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 code 4267) datum coordinates (and some others) to NAD83 (EPSG code 4267) within the United States. There are two set of grid shift files: NADCON and High Accuracy Reference Networks (HARN). NADCON shfts 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/.

Some of the NADCON grids, their areas of use, and source datums are shown in the following table.

Shift File Name	Area	Source Datum	Accuracy at 67% confidence (m)
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

Grid shift files come in two formats: binary and text. The files from the NGS are binary and have .las (latitude shift) and .los (longitude shift) extentions. Text grids may be created with the NGS nadgrd program and have .laa (latitude shift) and .loa (longitude shift) file extentions. Both types of files may be used here.

The grid names to use for transforming are parameters of this MathTransform. This parameter 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 main method of this class.

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:

NADCONreadme
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 version 6.5

Since:: 2.1
Author:: Rueben Schulz
See Also:: NADCON - North American Datum Conversion Utility, Serialized Form

Nested Class Summary

Nested Classes
Modifier and Type Class Description

static class NADCONTransform.Provider
The provider for NADCONTransform.

Field Summary
- Fields inherited from class Formattable
  SINGLE_LINE

Constructor Summary

Constructors
Constructor Description

NADCONTransform(URI latGridName, URI longGridName)
Constructs a NADCONTransform from the specified grid shift files.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`equals(Object object)`	Compares the specified object with this math transform for equality.
`ParameterDescriptorGroup`	`getParameterDescriptors()`	Returns the parameter descriptors for this math transform.
`ParameterValueGroup`	`getParameterValues()`	Returns the parameter values for this math transform.
`int`	`getSourceDimensions()`	Gets the dimension of input points (always 2).
`int`	`getTargetDimensions()`	Gets the dimension of output points (always 2).
`int`	`hashCode()`	Returns a hash value for this transform.
`MathTransform2D`	`inverse()`	Returns the inverse of this transform.
`void`	`inverseTransform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts)`	Transforms nad83 values to nad27.
`protected URL`	`locateGrid(URI uri)`
`static void`	`main(String... args)`	Used to set the preference for the default grid shift file location.
`void`	`transform(double[] srcPts, int srcOff, double[] dstPts, int dstOff, int numPts)`	Transforms a list of coordinate point ordinal values.

Methods inherited from class AbstractMathTransform
createTransformedShape, derivative, derivative, ensureNonNull, formatWKT, getName, isIdentity, needCopy, normalizeAngle, rollLongitude, transform, transform, transform, transform, transform

Methods inherited from class Formattable
cleanupThreadLocals, toString, toWKT, toWKT, toWKT, toWKT

Methods inherited from class Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface MathTransform
derivative, isIdentity, toWKT, transform, transform, transform, transform

Methods inherited from interface MathTransform2D
createTransformedShape, derivative, transform

- Constructor Detail
  - NADCONTransform
```
public NADCONTransform(URI latGridName,
                       URI longGridName)
                throws ParameterNotFoundException,
                       FactoryException
```
    Constructs a NADCONTransform from the specified grid shift files.
    
    Parameters:
    
    latGridName - path and name (or just name if GRID_LOCATION is set) to the latitude difference file. This will have a .las or .laa file extention.
    
    longGridName - path and name (or just name if GRID_LOCATION is set) to the longitude difference file. This will have a .los or .loa file extention.
    
    Throws:
    
    ParameterNotFoundException - if a math transform parameter cannot be found.
    
    FactoryException - if there is a problem creating this math transform (ie file extentions are unknown or there is an error reading the grid files)
- Method Detail
  - locateGrid
```
protected URL locateGrid(URI uri)
                  throws FactoryException
```
    Throws:
    
    FactoryException
  - getParameterDescriptors
```
public ParameterDescriptorGroup getParameterDescriptors()
```
    Returns the parameter descriptors for this math transform.
    
    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.
    
    Overrides:
    
    getParameterValues in class AbstractMathTransform
    
    Returns:
    
    A copy of the parameter values for this math transform.
    
    See Also:
    
    Operation.getParameterValues()
  - getSourceDimensions
```
public int getSourceDimensions()
```
    Gets the dimension of input points (always 2).
    
    Specified by:
    
    getSourceDimensions in interface MathTransform
    
    Specified by:
    
    getSourceDimensions in class AbstractMathTransform
    
    Returns:
    
    the source dimensions.
  - getTargetDimensions
```
public int getTargetDimensions()
```
    Gets the dimension of output points (always 2).
    
    Specified by:
    
    getTargetDimensions in interface MathTransform
    
    Specified by:
    
    getTargetDimensions in class AbstractMathTransform
    
    Returns:
    
    the target dimensions.
  - transform
```
public void transform(double[] srcPts,
                      int srcOff,
                      double[] dstPts,
                      int dstOff,
                      int numPts)
               throws TransformException
```
    Transforms a list of coordinate point ordinal values. This method is provided for efficiently transforming many points. The supplied array of ordinal values will contain packed ordinal values. For example, if the source dimension is 3, then the ordinals will be packed in this order: (x₀,y₀,z₀,
    x₁,y₁,z₁ ...). All input and output values are in decimal degrees.
    
    Specified by:
    
    transform in interface MathTransform
    
    Parameters:
    
    srcPts - the array containing the source point coordinates.
    
    srcOff - the offset to the first point to be transformed in the source array.
    
    dstPts - the array into which the transformed point coordinates are returned. May be the same than srcPts.
    
    dstOff - the offset to the location of the first transformed point that is stored in the destination array.
    
    numPts - the number of point objects to be transformed.
    
    Throws:
    
    TransformException - if the input point is outside the area covered by this grid.
  - inverseTransform
```
public void inverseTransform(double[] srcPts,
                             int srcOff,
                             double[] dstPts,
                             int dstOff,
                             int numPts)
                      throws TransformException
```
    Transforms nad83 values to nad27. Input and output values are in decimal degrees. This is done by itteratively finding a nad27 value that shifts to the input nad83 value. The input nad83 value is used as the first approximation.
    
    Parameters:
    
    srcPts - the array containing the source point coordinates.
    
    srcOff - the offset to the first point to be transformed in the source array.
    
    dstPts - the array into which the transformed point coordinates are returned. May be the same than srcPts.
    
    dstOff - the offset to the location of the first transformed point that is stored in the destination array.
    
    numPts - the number of point objects to be transformed.
    
    Throws:
    
    TransformException - if the input point is outside the area covered by this grid.
  - inverse
```
public MathTransform2D inverse()
```
    Returns the inverse of this transform.
    
    Specified by:
    
    inverse in interface MathTransform
    
    Specified by:
    
    inverse in interface MathTransform2D
    
    Overrides:
    
    inverse in class AbstractMathTransform
    
    Returns:
    
    the inverse of this transform
  - hashCode
```
public int hashCode()
```
    Description copied from class: AbstractMathTransform
    
    Returns a hash value for this transform.
    
    Overrides:
    
    hashCode in class AbstractMathTransform
  - equals
```
public boolean equals(Object object)
```
    Description copied from class: AbstractMathTransform
    
    Compares the specified object with this math transform for equality. The default implementation checks if object is an instance of the same class than this and use the same parameter descriptor. Subclasses should override this method in order to compare internal fields.
    
    Overrides:
    
    equals in class AbstractMathTransform
    
    Parameters:
    
    object - The object to compare with this transform.
    
    Returns:
    
    true if the given object is a transform of the same class and if, given identical source position, the transformed position would be the equals.
  - main
```
public static void main(String... args)
```
    Used to set the preference for the default grid shift file location. This allows grids parameters to be specified by name only, without the full path. This needs to be done only once, by the user. Path values may be simple file system paths or more complex text representations of a url. A value of "default" resets this preference to its default value.
    Example:
    
    java org.geotools.referencing.operation.transform.NADCONTransform file:///home/rschulz/GIS/NADCON/data
    Parameters:
    
    args - a single argument for the defualt location of grid shift files

Class NADCONTransform

Nested Class Summary

Field Summary

Fields inherited from class Formattable

Constructor Summary

Method Summary

Methods inherited from class AbstractMathTransform

Methods inherited from class Formattable

Methods inherited from class Object

Methods inherited from interface MathTransform

Methods inherited from interface MathTransform2D

Constructor Detail

NADCONTransform

Method Detail

locateGrid

getParameterDescriptors

getParameterValues

getSourceDimensions

getTargetDimensions

transform

inverseTransform

inverse

hashCode

equals

main