org.geotools.referencing.operation.transform
Class EarthGravitationalModel
Object
Formattable
AbstractMathTransform
VerticalTransform
EarthGravitationalModel
- All Implemented Interfaces:
- MathTransform
public final class EarthGravitationalModel
- extends VerticalTransform
Transforms vertical coordinates using coefficients from the
Earth
Gravitational Model.
Aknowledgement
This class is an adaption of Fortran code
clenqt.for
from the National Geospatial-Intelligence Agency and available in public domain. The
normalized geopotential coefficients file bundled in this module is an adaptation of
egm180.nor
file, with some spaces trimmed.
- Since:
- 2.3
- Author:
- Pierre Cardinal, Martin Desruisseaux
Method Summary |
ParameterDescriptorGroup |
getParameterDescriptors()
Returns the parameter descriptors for this math transform. |
ParameterValueGroup |
getParameterValues()
Returns the parameters for this math transform. |
double |
heightOffset(double longitude,
double latitude,
double height)
Returns the value to add to a height above the ellipsoid in order to get a
height above the geoid for the specified geographic coordinate. |
protected void |
load(String filename)
Loads the coefficients from the specified ASCII file and initialize the internal
clenshaw arrays. |
Methods inherited from class AbstractMathTransform |
createTransformedShape, derivative, derivative, ensureNonNull, equals, formatWKT, getName, hashCode, inverse, isIdentity, needCopy, rollLongitude, transform, transform, transform, transform |
load
protected void load(String filename)
throws IOException
- Loads the coefficients from the specified ASCII file and initialize the internal
clenshaw arrays.
Note: ASCII may looks like an unefficient format for binary distribution.
A binary file with coefficient values read by DataInput.readDouble()
would
be more compact than an uncompressed ASCII file. However, binary files are hard to
compress by the ZIP algorithm. Our experience show that a 675 kb uncompressed ASCII file
is only 222 kb after ZIP or JAR compression. The same data as a binary file is 257 kb
uncompressed and 248 kb compressed. So surprisingly, the ASCII file is more compact than
the binary file after compression. Since it is the primary format provided by the
Earth-Info web site, we use it directly in order to avoid a multiplication of formats.
- Parameters:
filename
- The filename (e.g. "WGS84.cof"
, relative to this class directory.
- Throws:
IOException
- if the file can't be read or has an invalid content.
heightOffset
public double heightOffset(double longitude,
double latitude,
double height)
throws TransformException
- Returns the value to add to a height above the ellipsoid in order to get a
height above the geoid for the specified geographic coordinate.
- Specified by:
heightOffset
in class VerticalTransform
- Parameters:
longitude
- The geodetic longitude, in decimal degrees.latitude
- The geodetic latitude, in decimal degrees.height
- The height above the ellipsoid in metres.
- Returns:
- The value to add in order to get the height above the geoid (in metres).
- Throws:
TransformException
- if the offset can't be computed for the specified coordinates.
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 parameters for this math transform.
- Overrides:
getParameterValues
in class AbstractMathTransform
- Returns:
- A copy of the parameter values for this math transform, or
null
. - See Also:
Operation.getParameterValues()
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