jwo.landserf.process.proj
Class TimeSpace

java.lang.Object
  jwo.landserf.process.proj.TimeSpace

All Implemented Interfaces:

Transformable

public class TimeSpace

extends Object

implements Transformable

Class for representing Mayhew time-space transformations. Projection is effectively a Lambert type transformation with u = lambda.x where lambda is orbital travel time over 2*PI v = 1/omega * ln(r/r0) where omega is the angular velocity in radians per time units (usually hours), r is the distance from a given centre point (e.g. centre of a city) and r0 is a constant that relates to the radius of the central zone.

Version:

2.2, 13th May, 2004.

Author:

Jo Wood taken from method suggested by Les Mayhew, 2004.

Field Summary

static int	FROM_TIME_SPACE Indicates a transformation from time-space to planar.
static int	TO_TIME_SPACE Indicates a transformation to time-space from planar coordinates.

Constructor Summary

TimeSpace(int direction, float centreX, float centreY, float r0, float lambda, float omega)
Initialises the time-space converter.

Method Summary

boolean	doInterpolation() Indicates whether the transformation should use nearest neighbour (false) or some interpolator (true).
String	getDescription() Provides a general description of the transformation.
Footprint	invTransformCoords(Footprint fpIn) Performs an inverse planar time-space transformation on the given location.
static void	main(String[] args) Generates a sample grid to test projection.
Footprint	planarToTimeSpace(float x, float y) Converts the given planar coordinates into a their time-space location.
void	setInterpolation(boolean doInterpolation) Sets whether the transformation should use nearest neighbour (false) or some interpolator (true).
Footprint	timeSpaceToPlanar(float u, float v) Converts the given time-space coordinates into a their planar location.
Footprint	transformCoords(Footprint fpIn) Performs a forward planar time-space transformation on the given location.

Methods inherited from class java.lang.Object

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

Field Detail

FROM_TIME_SPACE

public static final int FROM_TIME_SPACE

Indicates a transformation from time-space to planar.

See Also:

Constant Field Values

TO_TIME_SPACE

public static final int TO_TIME_SPACE

Indicates a transformation to time-space from planar coordinates.

See Also:

Constant Field Values

Constructor Detail

TimeSpace

public TimeSpace(int direction,
                 float centreX,
                 float centreY,
                 float r0,
                 float lambda,
                 float omega)

Initialises the time-space converter. Note that r0 should be in same distance units as coordinates centreX and centreY. Angular velocity omega will determine the time units used for the transformation.

Parameters:

centreX - Centre x coordinate from which radial distances measured.

centreY - Centre y coordinate from which radial distances measured.

r0 - Radius of central zone.

lambda - orbital speed coefficient.

omega - Radial speed coefficient.

Method Detail

main

public static void main(String[] args)

Generates a sample grid to test projection.

Parameters:

args - Command line arguements (ignored).

transformCoords

public Footprint transformCoords(Footprint fpIn)

Performs a forward planar time-space transformation on the given location. Note that the actual direction of the transformation is determined by the value of 'direction' in the constructor. If set to TO_TIME_SPACE this method will convert from planar into time-space, if set to FROM_TIME_SPACE it will convert from time-space into planar coordinates.

Specified by:

transformCoords in interface Transformable

Parameters:

fpIn - Incoming footprint to transform.

Returns:

Transformed footprint.

invTransformCoords

public Footprint invTransformCoords(Footprint fpIn)

Performs an inverse planar time-space transformation on the given location. Note that the actual direction of the transformation is determined by the value of 'direction' in the constructor. If set to TO_TIME_SPACE this method will convert from time-space to planar coordinates, if set to FROM_TIME_SPACE it will convert from planar to time-space coordinates.

Specified by:

invTransformCoords in interface Transformable

Parameters:

fpIn - Incoming footprint to transform.

Returns:

Transformed footprint.

getDescription

public String getDescription()

Provides a general description of the transformation.

Specified by:

getDescription in interface Transformable

Returns:

Description of the transformation.

doInterpolation

public boolean doInterpolation()

Indicates whether the transformation should use nearest neighbour (false) or some interpolator (true).

Specified by:

doInterpolation in interface Transformable

Returns:

True if transformation should perform some local interpolation.

setInterpolation

public void setInterpolation(boolean doInterpolation)

Sets whether the transformation should use nearest neighbour (false) or some interpolator (true).

Parameters:

doInterpolation - True if transformation should perform some local interpolation.

planarToTimeSpace

public Footprint planarToTimeSpace(float x,
                                   float y)

Converts the given planar coordinates into a their time-space location.

Parameters:

x - x-coordinate measured in distance units (e.g OSGB, UTM)

y - y-coordinate measured in distance units (e.g OSGB, UTM)

Returns:

timeSpace location.

timeSpaceToPlanar

public Footprint timeSpaceToPlanar(float u,
                                   float v)

Converts the given time-space coordinates into a their planar location.

Parameters:

u - x-coordinate measured in time units.

v - y-coordinate measured in time units.

Returns:

Planar location.