org.orekit.rugged.intersection.duvenhage

Class DuvenhageAlgorithm

java.lang.Object

org.orekit.rugged.intersection.duvenhage.DuvenhageAlgorithm

All Implemented Interfaces:

IntersectionAlgorithm

public class DuvenhageAlgorithm
extends Object
implements IntersectionAlgorithm

Digital Elevation Model intersection using Bernardt Duvenhage's algorithm.

The algorithm is described in the 2009 paper: Using An Implicit Min/Max KD-Tree for Doing Efficient Terrain Line of Sight Calculations.

Author:

Luc Maisonobe

Constructor Summary

Constructors

Constructor and Description
DuvenhageAlgorithm(TileUpdater updater, int maxCachedTiles, boolean flatBody) Simple constructor.

Method Summary

Methods

Modifier and Type	Method and Description
double	getElevation(double latitude, double longitude) Get elevation at a given ground point.
NormalizedGeodeticPoint	intersection(ExtendedEllipsoid ellipsoid, Vector3D position, Vector3D los) Compute intersection of line with Digital Elevation Model.
NormalizedGeodeticPoint	refineIntersection(ExtendedEllipsoid ellipsoid, Vector3D position, Vector3D los, NormalizedGeodeticPoint closeGuess) Refine intersection of line with Digital Elevation Model.

Methods inherited from class java.lang.Object

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

Constructor Detail

DuvenhageAlgorithm

public DuvenhageAlgorithm(TileUpdater updater,
                  int maxCachedTiles,
                  boolean flatBody)

Simple constructor.

Parameters:

updater - updater used to load Digital Elevation Model tiles

maxCachedTiles - maximum number of tiles stored in the cache

flatBody - if true, the body is considered flat, i.e. lines computed from entry/exit points in the DEM are considered to be straight lines also in geodetic coordinates. The sagitta resulting from real ellipsoid curvature is therefore not corrected in this case. As this computation is not costly (a few percents overhead), it is highly recommended to set this parameter to false. This flag is mainly intended for comparison purposes with other systems.

Method Detail

intersection

public NormalizedGeodeticPoint intersection(ExtendedEllipsoid ellipsoid,
                                   Vector3D position,
                                   Vector3D los)
                                     throws RuggedException

Compute intersection of line with Digital Elevation Model.

Specified by:

intersection in interface IntersectionAlgorithm

Parameters:

ellipsoid - reference ellipsoid

position - pixel position in ellipsoid frame

los - pixel line-of-sight in ellipsoid frame

Returns:

point at which the line first enters ground

Throws:

RuggedException - if intersection cannot be found

refineIntersection

public NormalizedGeodeticPoint refineIntersection(ExtendedEllipsoid ellipsoid,
                                         Vector3D position,
                                         Vector3D los,
                                         NormalizedGeodeticPoint closeGuess)
                                           throws RuggedException

Refine intersection of line with Digital Elevation Model.

This method is used to refine an intersection when a close guess is already known. The intersection is typically looked for by a direct cell intersection in the tile which already contains the close guess, or any similar very fast algorithm.

Specified by:

refineIntersection in interface IntersectionAlgorithm

Parameters:

ellipsoid - reference ellipsoid

position - pixel position in ellipsoid frame

los - pixel line-of-sight in ellipsoid frame

closeGuess - guess close to the real intersection

Returns:

point at which the line first enters ground

Throws:

RuggedException - if intersection cannot be found

getElevation

public double getElevation(double latitude,
                  double longitude)
                    throws RuggedException

Get elevation at a given ground point.

Specified by:

getElevation in interface IntersectionAlgorithm

Parameters:

latitude - ground point latitude

longitude - ground point longitude

Returns:

elevation at specified point

Throws:

RuggedException - if Digital Elevation Model does not cover point