Inheritance diagram for TSLTerrainVSInputEarthCurvature:

Detailed Description

An input object shim, which wraps another input object, and applies earth curvature corrections.

Corrections may be applied based on a visual, or radar line of sight. These corrections may be considered accurate within 40Km of the viewshed's center.

These calculations assume that the earth is spherical. The accuracy can be increased by calling the earthRadius() method. This should be supplied with the radius of the earth, for the required viewshed location.

The input data object must have a valid coordinate system for the correction to be applied, and must return height data in meters. If the source data does not use meters for the vertical units, the provided input object must perform the required conversion.

Using this object as part of a viewshed calculation will decrease the performance significantly. It is recommended that the resolution, and radius of the viewshed operation are limited in order to mitigate this effect.

When using this input object, combined with the TSLTerrainVSAlgorithmRFVS, a compositor such as TSLTerrainVSCompositorCumulativeVisibility should be used. This ensures that the percieved 'horizon' of the viewshed will be symmetrical, and that any marginal points are marked as visible.

Public Types
enum	LOSType { LOSTypeVisual , LOSTypeRadar }

Public Member Functions
	TSLTerrainVSInputEarthCurvature (TSLTerrainVSInput *input)

virtual bool	getData (unsigned int x, unsigned int y, double &value, const TSLTerrainVSAlgorithm::Parameters &params)

virtual TSLMUExtent	queryExtent () const

virtual unsigned int	width () const

virtual unsigned int	height () const

virtual const TSLCoordinateSystem *	coordinateSystem ()

void	earthRadius (double radius=6378137.0)

void	losType (TSLTerrainVSInputEarthCurvature::LOSType losType=TSLTerrainVSInputEarthCurvature::LOSTypeVisual)

virtual bool	offsetToLatLong (unsigned int x, unsigned int y, double &lat, double &lon)

virtual bool	offsetToMU (unsigned int x, unsigned int y, double &muX, double &muY)

virtual bool	MUToOffset (double muX, double muY, unsigned int &x, unsigned int &y)

virtual bool	LatLongToOffset (double lat, double lon, unsigned int &x, unsigned int &y)

virtual double	postDistanceX ()

virtual double	postDistanceY ()

virtual bool	valid (const TSLTerrainVSAlgorithm::Parameters &params) const

virtual void	processFinished ()

double	getEarthRadius () const

TSLTerrainVSInputEarthCurvature::LOSType	getLosType () const

Public Member Functions inherited from TSLTerrainVSInput
void	inc ()

void	dec ()

Additional Inherited Members
Protected Member Functions inherited from TSLTerrainVSInput
	TSLTerrainVSInput (unsigned int width, unsigned int height, TSLMUExtent extent, TSLCoordinateSystem *coordinateSystem)

	TSLTerrainVSInput ()

	TSLTerrainVSInput (const TSLTerrainVSInput &other)

virtual	~TSLTerrainVSInput ()

Protected Attributes inherited from TSLTerrainVSInput
unsigned int	m_width

unsigned int	m_height

TSLCoordinateSystem *	m_coordinateSystem

double	m_postDistanceX

double	m_postDistanceY

TSLMUExtent	m_extent

Member Enumeration Documentation

◆ LOSType

enum TSLTerrainVSInputEarthCurvature::LOSType

Enumerator
LOSTypeVisual
LOSTypeRadar

Constructor & Destructor Documentation

◆ TSLTerrainVSInputEarthCurvature()

TSLTerrainVSInputEarthCurvature::TSLTerrainVSInputEarthCurvature ( TSLTerrainVSInput * input )

Constructor.

Parameters

input The input object to read data from. Each height value read from this object will be corrected for earth curvature.

Member Function Documentation

◆ coordinateSystem()

virtual const TSLCoordinateSystem * TSLTerrainVSInputEarthCurvature::coordinateSystem ( )

virtual

Query the coordinate system of the input data.

Reimplemented from TSLTerrainVSInput.

◆ earthRadius()

void TSLTerrainVSInputEarthCurvature::earthRadius ( double radius = 6378137.0 )

Override the value used for the earth's radius. This value is in metres.

The calculations used by this object assume that the earth is spherical. The accuracy of these calculations can be increased by setting this valud to the radius of the earth, for the required viewshed location.

The default value is 6378137.0m.

◆ getData()

virtual bool TSLTerrainVSInputEarthCurvature::getData	(	unsigned int	x,
		unsigned int	y,
		double &	value,
		const TSLTerrainVSAlgorithm::Parameters &	params )

virtual

Query a height value from the input data.

If the valid() method has returned false, this method will never be called by the viewshed algorithm.

The location given to this method is specified as an offset, from the bottom-left of the data.

This method will read the height data from the input object, and adjust it for earth curvature. The adjustment is performed for either visual, or radar line of sight, depending on the value passed to the losType() method.

Parameters

x	The x offset to query
y	The y offset to query
value	Storage for the height value
params	The parameters of the viewshed operation

Implements TSLTerrainVSInput.

◆ getEarthRadius()

double TSLTerrainVSInputEarthCurvature::getEarthRadius ( ) const

Retrieve the value used for the earth's radius. This value is in metres.

◆ getLosType()

TSLTerrainVSInputEarthCurvature::LOSType TSLTerrainVSInputEarthCurvature::getLosType ( ) const

Retrieve the type of height correction to calculate.

◆ height()

virtual unsigned int TSLTerrainVSInputEarthCurvature::height ( ) const

virtual

Query the height of the input data

Reimplemented from TSLTerrainVSInput.

◆ LatLongToOffset()

virtual bool TSLTerrainVSInputEarthCurvature::LatLongToOffset	(	double	lat,
		double	lon,
		unsigned int &	x,
		unsigned int &	y )

virtual

Query the X/Y offset which corresponds to the provided Latitude/Longitude.

The base-class implementation of this method will call LatLongToMU on the input object's coordinate system.

Parameters

lat	The latitude of the point to convert
lon	The logitude of the point to convert
x	Storage for the returned x offset
y	Storage for the returned y offset

Returns: true if the point was converted, or false if an error occurred. false will be returned if the calculated offset is outside the input objects extent.

Reimplemented from TSLTerrainVSInput.

◆ losType()

void TSLTerrainVSInputEarthCurvature::losType ( TSLTerrainVSInputEarthCurvature::LOSType losType = TSLTerrainVSInputEarthCurvature::LOSTypeVisual )

Set the type of height correction to calculate.

◆ MUToOffset()

virtual bool TSLTerrainVSInputEarthCurvature::MUToOffset	(	double	muX,
		double	muY,
		unsigned int &	x,
		unsigned int &	y )

virtual

Query the X/Y offset which corresponds to the provided map unit location

Parameters

muX	The MU X coordinate of the point to convert
muY	The MU Y coordinate of the point to convert
x	Storage for the returned x offset
y	Storage for the returned y offset

Returns: true if the point was converted, or false if an error occurred. false will be returned if the calculated offset is outside the input objects extent.

Reimplemented from TSLTerrainVSInput.

◆ offsetToLatLong()

virtual bool TSLTerrainVSInputEarthCurvature::offsetToLatLong	(	unsigned int	x,
		unsigned int	y,
		double &	lat,
		double &	lon )

virtual

Query the geographic location of the provided X/Y offset, in Latitude/Longitude.

The base-class implementation of this method will call MUToLatLong on the input object's coordinate system.

Parameters

x	The X coordinate of the point to convert
y	The Y coordinate of the point to convert
lat	Storage for the returned latitude
lon	Storage for the returned longitude

Returns: true if the point was converted, or false if an error occurred.

Reimplemented from TSLTerrainVSInput.

◆ offsetToMU()

virtual bool TSLTerrainVSInputEarthCurvature::offsetToMU	(	unsigned int	x,
		unsigned int	y,
		double &	muX,
		double &	muY )

virtual

Query the geographic location of the provided X/Y offset, in map units.

Parameters

x	The X coordinate of the point to convert
y	The Y coordinate of the point to convert
muX	Storage for the returned MU X value
muY	Storage for the returned MU Y value

Reimplemented from TSLTerrainVSInput.

◆ postDistanceX()

virtual double TSLTerrainVSInputEarthCurvature::postDistanceX ( )

virtual

Query the horizontal post-distance of the input data.

This is the distance between sample points, in map units

Reimplemented from TSLTerrainVSInput.

◆ postDistanceY()

virtual double TSLTerrainVSInputEarthCurvature::postDistanceY ( )

virtual

Query the vertical post-distance of the input data.

This is the distance between sample points, in map units

Reimplemented from TSLTerrainVSInput.

◆ processFinished()

virtual void TSLTerrainVSInputEarthCurvature::processFinished ( )

virtual

This method will be called by the viewshed algorithm when the viewshed calculation has finished.

Implements TSLTerrainVSInput.

◆ queryExtent()

virtual TSLMUExtent TSLTerrainVSInputEarthCurvature::queryExtent ( ) const

virtual

Query the extent of the input data.

The units of this extent are defined by the source data, and this object's coordinate system.

Returns the input object's extent.

Reimplemented from TSLTerrainVSInput.

◆ valid()

virtual bool TSLTerrainVSInputEarthCurvature::valid ( const TSLTerrainVSAlgorithm::Parameters & params ) const

virtual

This method will be called by the viewshed algorithm, to provide the input object with a mechanism for initialisation, and an opportunity to terminate the viewshed calculation if required.

The extent provided by params.m_viewShedMUExtent should not be considered valid during this call, as it will not have been fully calculated.

This call will be forwarded to the valid() call of the wrapped input object,

Parameters

params The parameters of the viewshed operation.

Returns: true if the input object is valid, or false otherwise.

Implements TSLTerrainVSInput.

◆ width()

virtual unsigned int TSLTerrainVSInputEarthCurvature::width ( ) const

virtual

Query the width of the input data

Reimplemented from TSLTerrainVSInput.

Detailed Description

Public Types

Public Member Functions

Additional Inherited Members

Member Enumeration Documentation

◆ LOSType

Constructor & Destructor Documentation

◆ TSLTerrainVSInputEarthCurvature()

Member Function Documentation

◆ coordinateSystem()

◆ earthRadius()

◆ getData()

◆ getEarthRadius()

◆ getLosType()

◆ height()

◆ LatLongToOffset()

◆ losType()

◆ MUToOffset()

◆ offsetToLatLong()

◆ offsetToMU()

◆ postDistanceX()

◆ postDistanceY()

◆ processFinished()

◆ queryExtent()

◆ valid()

◆ width()