Package com.luciad.tea

Class TLcdLOSRadarPropagationFunction

java.lang.Object
com.luciad.tea.TLcdLOSRadarPropagationFunction
All Implemented Interfaces:
ILcdLOSPropagationFunction, ILcdLOSRadarPropagationFunction
public class TLcdLOSRadarPropagationFunction extends Object implements ILcdLOSRadarPropagationFunction
Computes the minimal heights from which one is visible around the center point of a line-of-sight coverage. These heights are assigned along the given azimuth and stored in the polar matrix view.

The visibility of a point is limited by the terrain, represented by the terrain elevation provider and by the cone of silence, represented by the minimum and maximum angle in the vertical direction. The area between these angles holds the visual field for the given azimuth. Both angles start from 0 at the ground to 180 at zenith.

The propagation function supports both radar and visual line-of-sight computations. The K-factor in the constructor is an indication of the reflection of the waves on the atmosphere. For radar line-of-sight computations, values should be greater than 1, usually 4/3. For visual line-of-sight computations the value should be equal to 1.

The matrix resulting from this propagation function can contain the following special values:

The following image gives a visual explanation of this propagation function. The green line denotes the result given this terrain profile and the visibility properties of the helicopter pilot.

Radar line-of-sight propagation function

  • Constructor Details

    • TLcdLOSRadarPropagationFunction

      public TLcdLOSRadarPropagationFunction(TLcdEarthRepresentationMode aEarthRepresentationMode, ALcdTerrainElevationProvider aTerrainElevationProvider, TLcdCoverageAltitudeMode aAltitudeMode, double aMinVerticalAngle, double aMaxVerticalAngle, double aKFactor)
      Creates a propagation function which computes the minimal height from which one is visible from the center point of a circular area. Note that the terrain elevation provider cannot be set to null, otherwise a NullPointerException will be thrown.

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

      The radar tilt angle is set to zero, meaning that the radar scans in a horizontal plane, the minimum and maximum viewing angles are constant independent of the viewing direction.

      Parameters:
      aEarthRepresentationMode - The mode indicating which earth representation to use.
      aTerrainElevationProvider - The terrain elevation provider.
      aAltitudeMode - The altitude mode indicating the definition of the resulting values.
      aMinVerticalAngle - The minimum angle of the vertical extent in degrees, starting from 0 at the ground to 180 at zenith. It is the minimum vertical angle when the radar tilt angle is set to zero.
      aMaxVerticalAngle - The maximum angle of the vertical extent in degrees, starting from 0 at the ground to 180 at zenith. It is the maximum vertical angle when the radar tilt angle is set to zero.
      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 line-of-sight computations.
      Throws:
      NullPointerException - when the argument aTerrainElevationProvider is null.
      IllegalArgumentException -
      • if the argument aEarthRepresentationMode is not one of the following expected values (TLcdEarthRepresentationMode.SPHERICAL_FIXED_RADIUS or TLcdEarthRepresentationMode.SPHERICAL_EULER_RADIUS,
      • if the aAltitudeMode is TLcdCoverageAltitudeMode.ABOVE_OBJECT,
      • if the argument aMinVerticalAngle or aMaxVerticalAngle lies outside the interval [0, 180] and
      • if the argument aKFactor is smaller than or equal to zero.

    • TLcdLOSRadarPropagationFunction

      public TLcdLOSRadarPropagationFunction(TLcdEarthRepresentationMode aEarthRepresentationMode, ALcdTerrainElevationProvider aTerrainElevationProvider, TLcdCoverageAltitudeMode aAltitudeMode, double aMinVerticalAngle, double aMaxVerticalAngle, double aMaxRadarTiltAngle, double aMaxRadarTiltAzimuth, double aKFactor)
      Creates a propagation function which computes the minimal height from which one is visible from the center point of a circular area. Note that the terrain elevation provider cannot be set to null, otherwise a NullPointerException will be thrown.

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

      The specified radar tilt angle is used to recomputed the minimum and maximum viewing angles in the method applyForAzimuthSFCT(double, ILcdLOSCoverageMatrix). If the computed viewing angle falls outside the viewing interval [0, 180], the angle outside the interval is clipped to either 0 or 180.

      Parameters:
      aEarthRepresentationMode - The mode indicating which earth representation to use.
      aTerrainElevationProvider - The terrain elevation provider.
      aAltitudeMode - The altitude mode indicating the definition of the resulting values.
      aMinVerticalAngle - The minimum angle of the vertical extent in degrees, starting from 0 at the ground to 180 at zenith. It is the minimum vertical angle when the radar tilt angle is set to zero.
      aMaxVerticalAngle - The maximum angle of the vertical extent in degrees, starting from 0 at the ground to 180 at zenith. It is the maximum vertical angle when the radar tilt angle is set to zero.
      aMaxRadarTiltAngle - The maximum radar tilt angle in degrees, starting from 0 at the horizontal plane to 90 at zenith.
      aMaxRadarTiltAzimuth - The azimuth in degrees where the maximum radar tilt angle occurs.
      aKFactor - A factor indicating the reflection of radar waves on the atmosphere. For radar computations, values should be greater than 1, usually 4/3. If equal to 1 this will produce the same result as direct line-of-sight computations.
      Throws:
      NullPointerException - when the argument aTerrainElevationProvider is null.
      IllegalArgumentException -
      • if the argument aEarthRepresentationMode is not one of the following expected values (TLcdEarthRepresentationMode.SPHERICAL_FIXED_RADIUS or TLcdEarthRepresentationMode.SPHERICAL_EULER_RADIUS,
      • if the aAltitudeMode is TLcdCoverageAltitudeMode.ABOVE_OBJECT,
      • if the argument aMinVerticalAngle or aMaxVerticalAngle lies outside the interval [0, 180],
      • if the argument aMaxRadarTiltAngle lies outside the interval [0, 90] and
      • if the argument aKFactor is smaller than or equal to zero.

    • TLcdLOSRadarPropagationFunction

      public TLcdLOSRadarPropagationFunction(TLcdEarthRepresentationMode aEarthRepresentationMode, ALcdTerrainElevationProvider aTerrainElevationProvider, TLcdCoverageAltitudeMode aAltitudeMode, double aMinVerticalAngle, double aMaxVerticalAngle, double aMaxRadarTiltAngle, double aMaxRadarTiltAzimuth, double aKFactor, TLcdLOSOptions aLOSOption)
      Creates a propagation function which computes the minimal height from which one is visible from the center point of a circular area. Note that the terrain elevation provider cannot be set to null, otherwise a NullPointerException will be thrown.

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

      The specified radar tilt angle is used to recomputed the minimum and maximum viewing angles in the method applyForAzimuthSFCT(double, ILcdLOSCoverageMatrix). If the computed viewing angle falls outside the viewing interval [0, 180], the angle outside the interval is clipped to either 0 or 180.

      Parameters:
      aEarthRepresentationMode - The mode indicating which earth representation to use.
      aTerrainElevationProvider - The terrain elevation provider.
      aAltitudeMode - The altitude mode indicating the definition of the resulting values.
      aMinVerticalAngle - The minimum angle of the vertical extent in degrees, starting from 0 at the ground to 180 at zenith. It is the minimum vertical angle when the radar tilt angle is set to zero.
      aMaxVerticalAngle - The maximum angle of the vertical extent in degrees, starting from 0 at the ground to 180 at zenith. It is the maximum vertical angle when the radar tilt angle is set to zero.
      aMaxRadarTiltAngle - The maximum radar tilt angle in degrees, starting from 0 at the horizontal plane to 90 at zenith.
      aMaxRadarTiltAzimuth - The azimuth in degrees where the maximum radar tilt angle occurs.
      aKFactor - A factor indicating the reflection of radar waves on the atmosphere. For radar computations, values should be greater than 1, usually 4/3. If equal to 1 this will produce the same result as direct line-of-sight computations.
      aLOSOption - A LOS option object containing parameters for the internals of this propagation function and its resulting coverages
      Throws:
      NullPointerException - when the argument aTerrainElevationProvider is null.
      IllegalArgumentException -
      • if the argument aEarthRepresentationMode is not one of the following expected values (TLcdEarthRepresentationMode.SPHERICAL_FIXED_RADIUS or TLcdEarthRepresentationMode.SPHERICAL_EULER_RADIUS,
      • if the aAltitudeMode is TLcdCoverageAltitudeMode.ABOVE_OBJECT,
      • if the argument aMinVerticalAngle or aMaxVerticalAngle lies outside the interval [0, 180],
      • if the argument aMaxRadarTiltAngle lies outside the interval [0, 90] and
      • if the argument aKFactor is smaller than or equal to zero.

  • Method Details

    • createLOSCoverageMatrix

      public ILcdLOSCoverageMatrix createLOSCoverageMatrix(ILcdLOSCoverage aLOSCoverage, ILcdGeoReference aMatrixReference)
      Description copied from interface: ILcdLOSPropagationFunction
      Creates a coverage matrix using the line-of-sight coverage aLOSCoverage and the matrix reference aMatrixReference. The result of this method is used as input parameter for the method applyForAzimuthSFCT, which will store the actual matrix values. The matrix should be consistent with the given coverage. This means that all matrix rows and columns represent evenly spaced radii and azimuths as defined by the radial and angular step sizes of the line-of-sight coverage.

      The method ILcdLOSPropagationFunction.initialize(com.luciad.tea.ILcdLOSCoverage, com.luciad.reference.ILcdGeoReference) is called with the same arguments as supplied with this method.

      The ILcdLOSCoverageMatrix created by this method is guaranteed to be capable of determining its own associatedPointX and associatedPointY properties. These values are not calculated by this ILcdPropagationFunction . An ILcdLOSPropagationFunction does not modify the values of the associatedPointX and associatedPointY for its created ILcdLOSCoverageMatrix.

      Specified by:
      createLOSCoverageMatrix in interface ILcdLOSPropagationFunction
      Parameters:
      aLOSCoverage - The covered area and the intermediate step sizes.
      aMatrixReference - The reference in which this matrix is defined.
      Returns:
      the created coverage matrix.

    • initialize

      public void initialize(ILcdLOSCoverage aLOSCoverage, ILcdGeoReference aMatrixReference)
      Description copied from interface: ILcdLOSPropagationFunction
      Initialize the propagation function with the given coverage aLOSCoverage and the given matrix reference aMatrixReference. For performance reasons, it is recommended that this method initializes all fields that are common to all computations or which do not depend on a specific azimuth.
      Specified by:
      initialize in interface ILcdLOSPropagationFunction
      Parameters:
      aLOSCoverage - The covered area to use.
      aMatrixReference - The matrix reference in which to compute the matrix values.

    • applyForAzimuthSFCT

      public void applyForAzimuthSFCT(double aAzimuth, ILcdLOSCoverageMatrix aLOSCoverageMatrixSFCT)
      Computes the minimal heights from which one is visible around the center point of a line-of-sight coverage for a given azimuth and stores the resulting heights in the line-of-sight coverage matrix.

      Note that this implementation assumes that the default value of a matrix entry corresponds to the value for invisible points (which is ILcdLOSRadarPropagationFunction.INVISIBLE). Refer to the class documentation for more information about the different special values.

      Specified by:
      applyForAzimuthSFCT in interface ILcdLOSPropagationFunction
      Parameters:
      aAzimuth - The azimuth in degrees.
      aLOSCoverageMatrixSFCT - The coverage matrix to update.
      Throws:
      NullPointerException - if the aLOSCoverageMatrixSFCT is null.

    • getEarthRepresentationMode

      public TLcdEarthRepresentationMode getEarthRepresentationMode()
      Description copied from interface: ILcdLOSRadarPropagationFunction
      Returns the earth representation mode used by this instance.
      Specified by:
      getEarthRepresentationMode in interface ILcdLOSRadarPropagationFunction
      Returns:
      the earth representation mode used by this instance.

    • getAltitudeMode

      public TLcdCoverageAltitudeMode getAltitudeMode()
      Description copied from interface: ILcdLOSRadarPropagationFunction
      Returns the altitude mode indicating the definition of the resulting line-of-sight values.
      Specified by:
      getAltitudeMode in interface ILcdLOSRadarPropagationFunction
      Returns:
      the altitude mode indicating the definition of the resulting line-of-sight values.

    • getKFactor

      public double getKFactor()
      Description copied from interface: ILcdLOSRadarPropagationFunction
      Returns the K-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 line-of-sight computations.
      Specified by:
      getKFactor in interface ILcdLOSRadarPropagationFunction
      Returns:
      the K-factor indicating the reflection of radar waves on the atmosphere.

    • getMaxVerticalAngle

      public double getMaxVerticalAngle()
      Description copied from interface: ILcdLOSRadarPropagationFunction
      Returns the maximum angle of the vertical extent in degrees, starting from 0 at the ground to 180 at zenith. It is the maximum vertical angle when the radar tilt angle is set to zero.
      Specified by:
      getMaxVerticalAngle in interface ILcdLOSRadarPropagationFunction
      Returns:
      the maximum angle of the vertical extent in degrees.

    • getMinVerticalAngle

      public double getMinVerticalAngle()
      Description copied from interface: ILcdLOSRadarPropagationFunction
      Returns the minimum angle of the vertical extent in degrees, starting from 0 at the ground to 180 at zenith. It is the minimum vertical angle when the radar tilt angle is set to zero.
      Specified by:
      getMinVerticalAngle in interface ILcdLOSRadarPropagationFunction
      Returns:
      the minimum angle of the vertical extent in degrees.

    • getMaxRadarTiltAngle

      public double getMaxRadarTiltAngle()
      Description copied from interface: ILcdLOSRadarPropagationFunction
      Returns the maximum radar tilt angle in degrees, starting from 0 at the horizontal plane to 90 at zenith.
      Specified by:
      getMaxRadarTiltAngle in interface ILcdLOSRadarPropagationFunction
      Returns:
      the maximum radar tilt angle in degrees.

    • getMaxRadarTiltAzimuth

      public double getMaxRadarTiltAzimuth()
      Description copied from interface: ILcdLOSRadarPropagationFunction
      Returns the azimuth in degrees where the maximum radar tilt angle occurs.
      Specified by:
      getMaxRadarTiltAzimuth in interface ILcdLOSRadarPropagationFunction
      Returns:
      the azimuth in degrees where the maximum radar tilt angle occurs.

    • getTerrainElevationProvider

      public ALcdTerrainElevationProvider getTerrainElevationProvider()
      Description copied from interface: ILcdLOSRadarPropagationFunction
      Returns the elevation provider used to retrieve the terrain elevation data.
      Specified by:
      getTerrainElevationProvider in interface ILcdLOSRadarPropagationFunction
      Returns:
      the elevation provider used to retrieve the terrain elevation data.