Package com.luciad.tea

Class TLcdP2PRadarPropagationFunctionSkyBackground

java.lang.Object

com.luciad.tea.TLcdP2PRadarPropagationFunctionSkyBackground

All Implemented Interfaces:

ILcdP2PPropagationFunction

public class TLcdP2PRadarPropagationFunctionSkyBackground
extends Object
implements ILcdP2PPropagationFunction

Computes the intervisibility with sky in background between the defining points. The definition of a visibility with sky in background states that in a given distance aSkyDistance after the end point no terrain background is found. This propagation function results in one of the following values:

• TLcdVisibilityStatus.VISIBLE: when the two points are visible to each other.
• TLcdVisibilityStatus.INVISIBLE: when the two points are invisible to each other.
• TLcdVisibilityStatus.UNCERTAIN: for points where the intervisibility is unknown. For example when no or invalid elevation data was found between the defining points.

The following image gives a visual explanation of this propagation function. The red line denotes the result given this terrain profile and the visibility properties of the helicopter pilot. The black line corresponds to the distance after the end point in which the terrain is taken into account as possible background.

Constructor Summary

Constructors

Constructor	Description
TLcdP2PRadarPropagationFunctionSkyBackground(TLcdEarthRepresentationMode aEarthRepresentationMode, ALcdTerrainElevationProvider aTerrainElevationProvider, double aKFactor, double aSkyDistance)	Creates a propagation function which computes the intervisibility with sky in background between the defining points.

Method Summary

Modifier and Type	Method	Description
TLcdVisibilityStatus	computeVisibility(ILcdP2PCoverage aP2PCoverage, ILcdGeoReference aComputationReference)	Computes the intervisibility with sky in background between the defining points of the coverage aP2PCoverage in the reference aComputationReference and returns the result as a TLcdVisibilityStatus.

Methods inherited from class java.lang.Object

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

Constructor Details

TLcdP2PRadarPropagationFunctionSkyBackground

public TLcdP2PRadarPropagationFunctionSkyBackground(TLcdEarthRepresentationMode aEarthRepresentationMode,
 ALcdTerrainElevationProvider aTerrainElevationProvider,
 double aKFactor,
 double aSkyDistance)

Creates a propagation function which computes the intervisibility with sky in background between the defining points. The definition of a visibility with sky in background states that there is no elevation data behind the end point for the given aSkyDistance.

Currently, two earth representation modes are supported. If another representation mode is used, an IllegalArgumentException will be thrown.

• TLcdEarthRepresentationMode.SPHERICAL_FIXED_RADIUS
• TLcdEarthRepresentationMode.SPHERICAL_EULER_RADIUS

Parameters:

aEarthRepresentationMode - The mode indicating which earth representation to use.

aTerrainElevationProvider - The terrain elevation provider.

aKFactor - A factor indicating the reflection of radar waves on the atmosphere. For radar computations, values should be greater than 1, usually 4/3. Setting the value equal to 1 will yield the same results as visual point-to-point computations.

aSkyDistance - The distance after the end point in which the terrain is taken into account as possible background. If no background is found, the end point is visible with sky as background.

Throws:

NullPointerException - when the argument aTerrainElevationProvider is null.

IllegalArgumentException - if the argument aKFactor is smaller than or equal to zero and if the argument aEarthRepresentationMode is not one of the expected values (TLcdEarthRepresentationMode.SPHERICAL_FIXED_RADIUS or TLcdEarthRepresentationMode.SPHERICAL_EULER_RADIUS).

Method Details

computeVisibility

public TLcdVisibilityStatus computeVisibility(ILcdP2PCoverage aP2PCoverage,
 ILcdGeoReference aComputationReference)

Computes the intervisibility with sky in background between the defining points of the coverage aP2PCoverage in the reference aComputationReference and returns the result as a TLcdVisibilityStatus.

A point is visible with sky in background if the point is intervisible from the start point and if in a given distance after the point no terrain background is found. The distance is configured in the constructor of this instance. Refer to the class documentation for more information about the different visibility values.

Note that currently only GEODETIC computation references are supported.

Specified by:

computeVisibility in interface ILcdP2PPropagationFunction

Parameters:

aP2PCoverage - The point-to-point coverage to use.

aComputationReference - The reference in which to compute the visibility.

Returns:

the computed visibility status.

Throws:

NullPointerException - if one of the arguments is null.