Class NADCONTransform
- Object
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- Formattable
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- AbstractMathTransform
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- NADCONTransform
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- 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 SURFnadgrd.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
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
NADCONTransform.Provider
The provider forNADCONTransform
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Field Summary
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Fields inherited from class Formattable
SINGLE_LINE
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Constructor Summary
Constructors Constructor Description NADCONTransform(URI latGridName, URI longGridName)
Constructs aNADCONTransform
from the specified grid shift files.
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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
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Methods inherited from class Formattable
cleanupThreadLocals, toString, toWKT, toWKT, toWKT, toWKT
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Methods inherited from interface MathTransform
derivative, isIdentity, toWKT, transform, transform, transform, transform
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Methods inherited from interface MathTransform2D
createTransformedShape, derivative, transform
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Constructor Detail
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NADCONTransform
public NADCONTransform(URI latGridName, URI longGridName) throws ParameterNotFoundException, FactoryException
Constructs aNADCONTransform
from the specified grid shift files.- Parameters:
latGridName
- path and name (or just name ifGRID_LOCATION
is set) to the latitude difference file. This will have a.las
or.laa
file extention.longGridName
- path and name (or just name ifGRID_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)
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Method Detail
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locateGrid
protected URL locateGrid(URI uri) throws FactoryException
- Throws:
FactoryException
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getParameterDescriptors
public ParameterDescriptorGroup getParameterDescriptors()
Returns the parameter descriptors for this math transform.- Overrides:
getParameterDescriptors
in classAbstractMathTransform
- Returns:
- The parameter descriptors for this math transform, or
null
. - See Also:
OperationMethod.getParameters()
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getParameterValues
public ParameterValueGroup getParameterValues()
Returns the parameter values for this math transform.- Overrides:
getParameterValues
in classAbstractMathTransform
- Returns:
- A copy of the parameter values for this math transform.
- See Also:
Operation.getParameterValues()
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getSourceDimensions
public int getSourceDimensions()
Gets the dimension of input points (always 2).- Specified by:
getSourceDimensions
in interfaceMathTransform
- Specified by:
getSourceDimensions
in classAbstractMathTransform
- Returns:
- the source dimensions.
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getTargetDimensions
public int getTargetDimensions()
Gets the dimension of output points (always 2).- Specified by:
getTargetDimensions
in interfaceMathTransform
- Specified by:
getTargetDimensions
in classAbstractMathTransform
- Returns:
- the target dimensions.
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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 interfaceMathTransform
- 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 thansrcPts
.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.
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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 thansrcPts
.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.
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inverse
public MathTransform2D inverse()
Returns the inverse of this transform.- Specified by:
inverse
in interfaceMathTransform
- Specified by:
inverse
in interfaceMathTransform2D
- Overrides:
inverse
in classAbstractMathTransform
- Returns:
- the inverse of this transform
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hashCode
public int hashCode()
Description copied from class:AbstractMathTransform
Returns a hash value for this transform.- Overrides:
hashCode
in classAbstractMathTransform
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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 ifobject
is an instance of the same class thanthis
and use the same parameter descriptor. Subclasses should override this method in order to compare internal fields.- Overrides:
equals
in classAbstractMathTransform
- 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.
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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
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