Public Member Functions | |
double | Arc () |
GeodesicData | ArcPosition (double a12) |
GeodesicData | ArcPosition (double a12, int outmask) |
double | Azimuth () |
Pair | AzimuthCosines () |
int | Capabilities () |
boolean | Capabilities (int testcaps) |
double | Distance () |
double | EquatorialArc () |
double | EquatorialAzimuth () |
Pair | EquatorialAzimuthCosines () |
double | Flattening () |
double | GenDistance (boolean arcmode) |
void | GenSetDistance (boolean arcmode, double s13_a13) |
GeodesicLine (Geodesic g, double lat1, double lon1, double azi1) | |
GeodesicLine (Geodesic g, double lat1, double lon1, double azi1, int caps) | |
double | Latitude () |
double | Longitude () |
double | MajorRadius () |
GeodesicData | Position (boolean arcmode, double s12_a12, int outmask) |
GeodesicData | Position (double s12) |
GeodesicData | Position (double s12, int outmask) |
void | SetDistance (double s13) |
Protected Member Functions | |
GeodesicLine (Geodesic g, double lat1, double lon1, double azi1, double salp1, double calp1, int caps, boolean arcmode, double s13_a13) | |
Private Member Functions | |
GeodesicLine () | |
boolean | Init () |
void | LineInit (Geodesic g, double lat1, double lon1, double azi1, double salp1, double calp1, int caps) |
Private Attributes | |
double | _a |
double | _a13 |
double | _C1a [] |
int | _caps |
double | _lat1 |
Static Private Attributes | |
static final int | nC1_ = Geodesic.nC1_ |
static final int | nC1p_ = Geodesic.nC1p_ |
static final int | nC2_ = Geodesic.nC2_ |
static final int | nC3_ = Geodesic.nC3_ |
static final int | nC4_ = Geodesic.nC4_ |
A geodesic line.
GeodesicLine facilitates the determination of a series of points on a single geodesic. The starting point (lat1, lon1) and the azimuth azi1 are specified in the constructor; alternatively, the {Geodesic.Line} method can be used to create a GeodesicLine. #Position Position} returns the location of point 2 a distance s12 along the geodesic. Alternatively #ArcPosition ArcPosition} gives the position of point 2 an arc length a12 along the geodesic. You can register the position of a reference point 3 a distance (arc length), s13 (a13) along the geodesic with the SetDistance (SetArc) functions. Points a fractional distance along the line can be found by providing, for example, 0.5 * Distance as an argument to Position. The Geodesic.InverseLine or Geodesic.DirectLine methods return GeodesicLine objects with point 3 set to the point 2 of the corresponding geodesic problem. GeodesicLine objects created with the public constructor or with Geodesic.Line have s13 and a13 set to NaNs.
The calculations are accurate to better than 15 nm (15 nanometers). See Sec. 9 of arXiv:1102.1215v1 for details. The algorithms used by this class are based on series expansions using the flattening f as a small parameter. These are only accurate for |f| < 0.02; however reasonably accurate results will be obtained for |f| < 0.2.
The algorithms are described in
Here's an example of using this class
public class GeodesicLineTest {// Print waypoints between JFK and SINGeodesic geod = Geodesic.WGS84;doublelat1 = 40.640, lon1 = -73.779, // JFKlat2 = 1.359, lon2 = 103.989; // SINGeodesicLine line = geod.InverseLine(lat1, lon1, lat2, lon2,GeodesicMask.DISTANCE_IN |GeodesicMask.LATITUDE |GeodesicMask.LONGITUDE);double ds0 = 500e3; // Nominal distance between points = 500 km// The number of intervalsint num = (int)(Math.ceil(line.Distance() / ds0));{// Use intervals of equal lengthdouble ds = line.Distance() / num;GeodesicMask.LATITUDE |GeodesicMask.LONGITUDE);}}{// Slightly faster, use intervals of equal arc lengthdouble da = line.Arc() / num;GeodesicMask.LATITUDE |GeodesicMask.LONGITUDE);}}}}
Definition at line 93 of file GeodesicLine.java.
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Constructor for a geodesic line staring at latitude lat1, longitude lon1, and azimuth azi1 (all in degrees).
g | A Geodesic object used to compute the necessary information about the GeodesicLine. |
lat1 | latitude of point 1 (degrees). |
lon1 | longitude of point 1 (degrees). |
azi1 | azimuth at point 1 (degrees). |
lat1 should be in the range [−90°, 90°].
If the point is at a pole, the azimuth is defined by keeping lon1 fixed, writing lat1 = ±(90° − ε), and taking the limit ε → 0+.
Definition at line 127 of file GeodesicLine.java.
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Constructor for a geodesic line staring at latitude lat1, longitude lon1, and azimuth azi1 (all in degrees) with a subset of the capabilities included.
g | A Geodesic object used to compute the necessary information about the GeodesicLine. |
lat1 | latitude of point 1 (degrees). |
lon1 | longitude of point 1 (degrees). |
azi1 | azimuth at point 1 (degrees). |
caps | bitor'ed combination of GeodesicMask values specifying the capabilities the GeodesicLine object should possess, i.e., which quantities can be returned in calls to Position. |
The GeodesicMask values are
Definition at line 177 of file GeodesicLine.java.
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Definition at line 276 of file GeodesicLine.java.
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A default constructor. If GeodesicLine.Position is called on the resulting object, it returns immediately (without doing any calculations). The object can be set with a call to Geodesic.Line. Use {} to test whether object is still in this uninitialized state. (This constructor was useful in C++, e.g., to allow vectors of GeodesicLine objects. It may not be needed in Java, so make it private.)
Definition at line 292 of file GeodesicLine.java.
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Definition at line 744 of file GeodesicLine.java.
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Compute the position of point 2 which is an arc length a12 (degrees) from point 1.
a12 | arc length from point 1 to point 2 (degrees); it can be negative. |
The values of lon2 and azi2 returned are in the range [−180°, 180°].
The GeodesicLine object must have been constructed with caps |= GeodesicMask#DISTANCE_IN; otherwise no parameters are set.
Definition at line 355 of file GeodesicLine.java.
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Compute the position of point 2 which is an arc length a12 (degrees) from point 1 and with a subset of the geodesic results returned.
a12 | arc length from point 1 to point 2 (degrees); it can be negative. |
outmask | a bitor'ed combination of GeodesicMask values specifying which results should be returned. |
Requesting a value which the GeodesicLine object is not capable of computing is not an error (no parameters will be set). The value of lon2 returned is in the range [−180°, 180°], unless the outmask includes the GeodesicMask#LONG_UNROLL flag.
Definition at line 374 of file GeodesicLine.java.
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Definition at line 657 of file GeodesicLine.java.
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Definition at line 664 of file GeodesicLine.java.
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Definition at line 714 of file GeodesicLine.java.
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testcaps | a set of bitor'ed GeodesicMask values. |
Definition at line 720 of file GeodesicLine.java.
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Definition at line 739 of file GeodesicLine.java.
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Definition at line 691 of file GeodesicLine.java.
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Definition at line 673 of file GeodesicLine.java.
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Definition at line 682 of file GeodesicLine.java.
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Definition at line 707 of file GeodesicLine.java.
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The distance or arc length to point 3.
arcmode | boolean flag determining the meaning of returned value. |
Definition at line 733 of file GeodesicLine.java.
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Specify position of point 3 in terms of either distance or arc length.
arcmode | boolean flag determining the meaning of the second parameter; if arcmode is false, then the GeodesicLine object must have been constructed with caps |= GeodesicMask#DISTANCE_IN. |
s13_a13 | if arcmode is false, this is the distance from point 1 to point 3 (meters); otherwise it is the arc length from point 1 to point 3 (degrees); it can be negative. |
Definition at line 630 of file GeodesicLine.java.
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Definition at line 640 of file GeodesicLine.java.
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Definition at line 645 of file GeodesicLine.java.
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Definition at line 188 of file GeodesicLine.java.
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Definition at line 651 of file GeodesicLine.java.
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Definition at line 700 of file GeodesicLine.java.
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The general position function. Position and ArcPosition are defined in terms of this function.
arcmode | boolean flag determining the meaning of the second parameter; if arcmode is false, then the GeodesicLine object must have been constructed with caps |= GeodesicMask#DISTANCE_IN. |
s12_a12 | if arcmode is false, this is the distance between point 1 and point 2 (meters); otherwise it is the arc length between point 1 and point 2 (degrees); it can be negative. |
outmask | a bitor'ed combination of GeodesicMask values specifying which results should be returned. |
The GeodesicMask values possible for outmask are
Requesting a value which the GeodesicLine object is not capable of computing is not an error; Double.NaN is returned instead.
Definition at line 423 of file GeodesicLine.java.
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Compute the position of point 2 which is a distance s12 (meters) from point 1.
s12 | distance from point 1 to point 2 (meters); it can be negative. |
The values of lon2 and azi2 returned are in the range [−180°, 180°].
The GeodesicLine object must have been constructed with caps |= GeodesicMask#DISTANCE_IN; otherwise no parameters are set.
Definition at line 311 of file GeodesicLine.java.
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Compute the position of point 2 which is a distance s12 (meters) from point 1 and with a subset of the geodesic results returned.
s12 | distance from point 1 to point 2 (meters); it can be negative. |
outmask | a bitor'ed combination of GeodesicMask values specifying which results should be returned. |
The GeodesicLine object must have been constructed with caps |= GeodesicMask#DISTANCE_IN; otherwise no parameters are set. Requesting a value which the GeodesicLine object is not capable of computing is not an error (no parameters will be set). The value of lon2 returned is normally in the range [−180°, 180°]; however if the outmask includes the GeodesicMask#LONG_UNROLL flag, the longitude is "unrolled" so that the quantity lon2 − lon1 indicates how many times and in what sense the geodesic encircles the ellipsoid.
Definition at line 334 of file GeodesicLine.java.
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Specify position of point 3 in terms of distance.
s13 | the distance from point 1 to point 3 (meters); it can be negative. |
This is only useful if the GeodesicLine object has been constructed with caps |= GeodesicMask#DISTANCE_IN.
Definition at line 598 of file GeodesicLine.java.
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Definition at line 102 of file GeodesicLine.java.
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Definition at line 105 of file GeodesicLine.java.
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Definition at line 107 of file GeodesicLine.java.
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Definition at line 109 of file GeodesicLine.java.
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Definition at line 101 of file GeodesicLine.java.
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Definition at line 95 of file GeodesicLine.java.
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Definition at line 96 of file GeodesicLine.java.
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Definition at line 97 of file GeodesicLine.java.
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Definition at line 98 of file GeodesicLine.java.
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Definition at line 99 of file GeodesicLine.java.