Package gov.nasa.worldwind.util.measure

Class LengthMeasurer

  • All Implemented Interfaces:
    MeasurableLength
    Direct Known Subclasses:
    AreaMeasurer
    public class LengthMeasurer
extends java.lang.Object
implements MeasurableLength
    Utility class to measure length along a path on a globe.

    The measurer must be provided a list of at least two positions to be able to compute a distance.

    Segments which are longer then the current maxSegmentLength will be subdivided along lines following the current pathType - AVKey.LINEAR, AVKey.RHUMB_LINE or AVKey.GREAT_CIRCLE.

    If the measurer is set to follow terrain, the computed length will account for terrain deformations as if someone was walking along that path. Otherwise the length is the sum of the cartesian distance between the positions.

    When following terrain the measurer will sample terrain elevations at regular intervals along the path. The minimum number of samples used for the whole length can be set with setLengthTerrainSamplingSteps(). However, the minimum sampling interval is 30 meters.

    See Also:
    MeasureTool

    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected double length  

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      protected void clearCachedValues()  
      protected double computeLength​(Globe globe, boolean followTerrain)  
      java.lang.String getAVKeyPathType()
      Get the type of path used when subdividing long segments, one of AVKey.GREAT_CIRCLE, which draws segments as a great circle, AVKey.LINEAR, which determines the intermediate positions between segments by interpolating the segment endpoints, or AVKey.RHUMB_LINE, which draws segments as a line of constant heading.
      Sector getBoundingSector()  
      double getLength​(Globe globe)
      Get the path length in meter.
      double getLengthTerrainSamplingSteps()
      Get the number of terrain elevation samples used along the path to approximate it's terrain following length.
      double getMaxSegmentLength()
      Get the maximum length a segment can have before being subdivided along a line following the current pathType.
      java.util.ArrayList<? extends Position> getPositions()  
      boolean isClosedShape()
      Returns true if the current position list describe a closed path - one which last position is equal to the first.
      boolean isFollowTerrain()  
      void setFollowTerrain​(boolean followTerrain)
      Set whether measurements should account for terrain deformations.
      void setLengthTerrainSamplingSteps​(double steps)
      Set the number of terrain elevation samples to be used along the path to approximate it's terrain following length.
      void setMaxSegmentLength​(double length)
      Set the maximum length a segment can have before being subdivided along a line following the current pathType.
      void setPathType​(java.lang.String pathType)
      Sets the type of path used when subdividing long segments, one of AVKey.GREAT_CIRCLE, which draws segments as a great circle, AVKey.LINEAR, which determines the intermediate positions between segments by interpolating the segment endpoints, or AVKey.RHUMB_LINE, which draws segments as a line of constant heading.
      void setPositions​(java.lang.Iterable<? extends Position> positions)  
      void setPositions​(java.util.ArrayList<? extends LatLon> positions, double elevation)  
      void setPositions​(java.util.ArrayList<? extends Position> positions)  
      protected static java.util.ArrayList<? extends Position> subdividePositions​(Globe globe, java.util.ArrayList<? extends Position> positions, double maxLength, boolean followTerrain, java.lang.String avkeyPathType)
      Subdivide a list of positions so that no segment is longer then the provided maxLength.
      protected static java.util.ArrayList<? extends Position> subdividePositions​(Globe globe, java.util.ArrayList<? extends Position> positions, double maxLength, boolean followTerrain, java.lang.String pathType, int start, int count)
      Subdivide a list of positions so that no segment is longer then the provided maxLength.

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • length

        protected double length

    • Constructor Detail

      • LengthMeasurer

        public LengthMeasurer()

      • LengthMeasurer

        public LengthMeasurer​(java.util.ArrayList<? extends Position> positions)

    • Method Detail

      • clearCachedValues

        protected void clearCachedValues()

      • getPositions

        public java.util.ArrayList<? extends Position> getPositions()

      • setPositions

        public void setPositions​(java.util.ArrayList<? extends LatLon> positions,
                         double elevation)

      • setPositions

        public void setPositions​(java.lang.Iterable<? extends Position> positions)

      • setPositions

        public void setPositions​(java.util.ArrayList<? extends Position> positions)

      • isFollowTerrain

        public boolean isFollowTerrain()

      • setFollowTerrain

        public void setFollowTerrain​(boolean followTerrain)
        Set whether measurements should account for terrain deformations.
        Parameters:
        followTerrain - set to true if measurements should account for terrain deformations.

      • getAVKeyPathType

        public java.lang.String getAVKeyPathType()
        Get the type of path used when subdividing long segments, one of AVKey.GREAT_CIRCLE, which draws segments as a great circle, AVKey.LINEAR, which determines the intermediate positions between segments by interpolating the segment endpoints, or AVKey.RHUMB_LINE, which draws segments as a line of constant heading.
        Returns:
        The path type

      • setPathType

        public void setPathType​(java.lang.String pathType)
        Sets the type of path used when subdividing long segments, one of AVKey.GREAT_CIRCLE, which draws segments as a great circle, AVKey.LINEAR, which determines the intermediate positions between segments by interpolating the segment endpoints, or AVKey.RHUMB_LINE, which draws segments as a line of constant heading.
        Parameters:
        pathType - the type of path to measure.

      • getMaxSegmentLength

        public double getMaxSegmentLength()
        Get the maximum length a segment can have before being subdivided along a line following the current pathType.
        Returns:
        the maximum length a segment can have before being subdivided.

      • setMaxSegmentLength

        public void setMaxSegmentLength​(double length)
        Set the maximum length a segment can have before being subdivided along a line following the current pathType.
        Parameters:
        length - the maximum length a segment can have before being subdivided.

      • getBoundingSector

        public Sector getBoundingSector()

      • isClosedShape

        public boolean isClosedShape()
        Returns true if the current position list describe a closed path - one which last position is equal to the first.
        Returns:
        true if the current position list describe a closed path.

      • getLengthTerrainSamplingSteps

        public double getLengthTerrainSamplingSteps()
        Get the number of terrain elevation samples used along the path to approximate it's terrain following length.
        Returns:
        the number of terrain elevation samples used.

      • setLengthTerrainSamplingSteps

        public void setLengthTerrainSamplingSteps​(double steps)
        Set the number of terrain elevation samples to be used along the path to approximate it's terrain following length.
        Parameters:
        steps - the number of terrain elevation samples to be used.

      • getLength

        public double getLength​(Globe globe)
        Get the path length in meter.

        If the measurer is set to follow terrain, the computed length will account for terrain deformations as if someone was walking along that path. Otherwise the length is the sum of the cartesian distance between each positions.

        Specified by:
        getLength in interface MeasurableLength
        Parameters:
        globe - the globe to draw terrain information from.
        Returns:
        the current path length or -1 if the position list is too short.

      • computeLength

        protected double computeLength​(Globe globe,
                               boolean followTerrain)

      • subdividePositions

        protected static java.util.ArrayList<? extends Position> subdividePositions​(Globe globe,
                                                                            java.util.ArrayList<? extends Position> positions,
                                                                            double maxLength,
                                                                            boolean followTerrain,
                                                                            java.lang.String avkeyPathType)
        Subdivide a list of positions so that no segment is longer then the provided maxLength.

        If needed, new intermediate positions will be created along lines that follow the given PathType - one of AVKey.LINEAR, AVKey.RHUMB_LINE or AVKey.GREAT_CIRCLE. All position elevations will be either at the terrain surface if followTerrain is true, or interpolated according to the original elevations.

        Parameters:
        globe - the globe to draw elevations and points from.
        positions - the original position list
        maxLength - the maximum length for one segment.
        followTerrain - true if the positions should be on the terrain surface.
        avkeyPathType - the type of path to use in between two positions.
        Returns:
        a list of positions with no segment longer then maxLength and elevations following terrain or not.

      • subdividePositions

        protected static java.util.ArrayList<? extends Position> subdividePositions​(Globe globe,
                                                                            java.util.ArrayList<? extends Position> positions,
                                                                            double maxLength,
                                                                            boolean followTerrain,
                                                                            java.lang.String pathType,
                                                                            int start,
                                                                            int count)
        Subdivide a list of positions so that no segment is longer then the provided maxLength. Only the positions between start and start + count - 1 will be processed.

        If needed, new intermediate positions will be created along lines that follow the given pathType - one of AVKey.LINEAR, AVKey.RHUMB_LINE or AVKey.GREAT_CIRCLE. All position elevations will be either at the terrain surface if followTerrain is true, or interpolated according to the original elevations.

        Parameters:
        globe - the globe to draw elevations and points from.
        positions - the original position list
        maxLength - the maximum length for one segment.
        followTerrain - true if the positions should be on the terrain surface.
        pathType - the type of path to use in between two positions.
        start - the first position index in the original list.
        count - how many positions from the original list have to be processed and returned.
        Returns:
        a list of positions with no segment longer then maxLength and elevations following terrain or not.