org.tinfour.utils.loaders

Class SimpleGeographicTransform

java.lang.Object

org.tinfour.utils.loaders.SimpleGeographicTransform

All Implemented Interfaces:

ICoordinateTransform

public class SimpleGeographicTransform
extends Object
implements ICoordinateTransform

Provides a rudimentary implementation of a geographic transform. This implementation is intended as a demonstration, and does not provide sufficient accuracy for true Geographic Information Analysis applications.

This transform will map geographic coordinates to an planar coordinate system that can be used for Tinfour processing. The transformation attempts to scale the coordinates to an isotropic coordinate system with positions given in meters. It is important to note that this transform is not a true map projection. In particular, the transformation is not suitable for data collected over areas larger than a few hundred kilometers and is not suitable for coordinates in polar areas. Because it assumes a spherical Earth, it is not suitable for high-precision analysis.

Field Summary

Fields

Modifier and Type	Field and Description
static double	earthFlattening The flattening ratio for the Earth, as specified by World Geodetic Survey 1984.
static double	earthSemiMajorAxis Radius of the Earth at the equator, as specified by World Geodetic Survey 1984 (WGS84).
static double	earthSemiMinorAxis Radius of the Earth at the poles, as specified by World Geodetic Survey 1984 (WGS84).

Constructor Summary

Constructors

Constructor and Description
SimpleGeographicTransform(double centerLatitude, double centerLongitude, LinearUnits linearUnits) Constructs a transform with the origin at the specified center latitude and longitude.

Method Summary

Modifier and Type	Method and Description
boolean	forward(double xSource, double ySource, CoordinatePair c) Transforms a point in a source coordinate system to the equivalent output.
double	getCenterLatitude() Gets the center latitude used for this projection
double	getCenterLongitude() Gets the center longitude used for this projection
LinearUnits	getLinearUnits() Gets the linear units specified for this object
boolean	inverse(double xOutput, double yOutput, CoordinatePair c) Transforms a point in an output coordinate system to the equivalent point in the source coordinate system.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

earthSemiMajorAxis

public static final double earthSemiMajorAxis

Radius of the Earth at the equator, as specified by World Geodetic Survey 1984 (WGS84).

See Also:

Constant Field Values

earthFlattening

public static final double earthFlattening

The flattening ratio for the Earth, as specified by World Geodetic Survey 1984.

See Also:

Constant Field Values

earthSemiMinorAxis

public static final double earthSemiMinorAxis

Radius of the Earth at the poles, as specified by World Geodetic Survey 1984 (WGS84).

See Also:

Constant Field Values

Constructor Detail

SimpleGeographicTransform

public SimpleGeographicTransform(double centerLatitude,
                                 double centerLongitude,
                                 LinearUnits linearUnits)

Constructs a transform with the origin at the specified center latitude and longitude. All coordinates are given in degrees. The maximum absolute latitude is 87.5 degrees, but the accuracy of this transformation is degraded at high latitudes.

Parameters:

centerLatitude - a valid latitude, in degrees, positive to the North, negative to the South.

centerLongitude - a valid longitude, in degrees, positive to the East, negative to the West.

linearUnits - the linear unit system to be used for the transformation, most commonly meters or feet.

Method Detail

forward

public boolean forward(double xSource,
                       double ySource,
                       CoordinatePair c)

Description copied from interface: ICoordinateTransform

Transforms a point in a source coordinate system to the equivalent output. The return value indicates whether the transform was successful. In some cases, a transform may be defined only over a finite region.

All transforms are assumed to be fully invertible (bijective) over their domain. If a forward transform is defined for a set of input coordinates, then the inverse transform must be defined for the resulting output coordinates.

Specified by:

forward in interface ICoordinateTransform

Parameters:

xSource - the x value in the source coordinate system

ySource - the y value in the source coordinate system

c - a simple container to receive the results of the computation, the transformed coordinates for (xSource, ySource).

Returns:

true if the transform is successful; otherwise, false

inverse

public boolean inverse(double xOutput,
                       double yOutput,
                       CoordinatePair c)

Description copied from interface: ICoordinateTransform

Transforms a point in an output coordinate system to the equivalent point in the source coordinate system. The return value indicates whether the transform was successful. In some cases, a transform may be defined only over a finite region.

All transforms are assumed to be fully invertible (bijective) over their domain. If a forward transform is defined for a set of input coordinates, then the inverse transform must be defined for the resulting output coordinates.

Specified by:

inverse in interface ICoordinateTransform

Parameters:

xOutput - x value in the transformed coordinate system

yOutput - y value in the transformed coordiante system

c - a simple container to receive the results of the computation, the transformed coordinates for (xSource, ySource).

Returns:

true if the inverse transform is successful; otherwise, false

getCenterLatitude

public double getCenterLatitude()

Gets the center latitude used for this projection

Returns:

a value in degrees, in the range -87.5 to 87.5

getCenterLongitude

public double getCenterLongitude()

Gets the center longitude used for this projection

Returns:

a value in degrees

getLinearUnits

public LinearUnits getLinearUnits()

Gets the linear units specified for this object

Returns:

a valid instance