go-geodesy is a package of geodesy-related utilities made in golang, including ellipsoid constants for development of geographic and geospatial implementations
import "github.com/lggomez/go-geodesy"
typePoint[2]float64Point represents a latitude-longitude pair in decimal degrees
Constants
const(
LatLowerBound=float64(-90)
LatUpperBound=float64(90)
LonLowerBound=float64(-180)
LonUpperBound=float64(180)
)func(pPoint)Antipode()PointAntipode returns a new point representing the geographical antipode of p
func(pPoint)Equals(p2Point)boolEquals returns whether p is equal in latitude and longitude to p2
func(pPoint)IsAntipodeOf(p2Point)boolIsAntipodeOf returns whether p is the exact antipode of p2 or not
func(pPoint)Lat()float64Lat returns point p's latitude
func(pPoint)LatRadians()float64LatRadians returns point p's latitude in radians
func(pPoint)Lon()float64Lon returns point p's longitude
func(pPoint)LonRadians()float64LonRadians returns point p's longitude in radians
import "github.com/lggomez/go-geodesy/distance"
funcHaversine(p1,p2geodesy.Point)float64Haversine calculates the ellipsoidal distance in meters between 2 points using the Haversine formula and the WGS-84 ellipsoid constants. If any of the points does not constitute a valid geographic coordinate, the returned distance will be math.NaN().
funcVincentyInverse(p1,p2geodesy.Point,accuracyfloat64,calculateAzimuthbool) (float64,float64,float64)VincentyInverse calculates the ellipsoidal distance in meters and azimuth in degrees between 2 points using the inverse Vincenty formulae and the WGS-84 ellipsoid constants. As it is an iterative operation it will converge to the defined accuracy, if accuracy < 0 it will use the default accuracy of 1e-12 (approximately 0.06 mm, magnitude should be no bigger than 1e-6). If calculateAzimuth is set to true, it will compute the forward and reverse azimuths (otherwise, these default to math.NaN()). If any of the points does not constitute a valid geographic coordinate, the returned distance will be math.NaN().
The following notations are used in the implementation:
* a length of semi-major axis of the ellipsoid (radius at equator)
* ƒ flattening of the ellipsoid
* b = (1 − ƒ) a length of semi-minor axis of the ellipsoid (radius at the poles)
* u1 = arctan( (1 − ƒ) tan lat1 ) reduced latitude for p1 (latitude on the auxiliary sphere);
* u2 = arctan( (1 − ƒ) tan lat2 ) reduced latitude for p2 (latitude on the auxiliary sphere);
* L1, L2 longitude of the points;
* L = L2 − L1 difference in longitude of two points;
* λ Difference in longitude of the points on the auxiliary sphere;
* α1, α2 forward azimuths at the points;
* α forward azimuth of the geodesic at the equator, if it were extended that far;
* s ellipsoidal distance between the two points;
* σ angular separation between points;
* σ1 angular separation between the point and the equator;
* σm angular separation between the midpoint of the line and the equator;
import "github.com/lggomez/go-geodesy/ellipsoids"
const(
// Geocentric gravitational constant GM, defined in (m^3)/(s^2)
GRS80_GEOCENTRIC_GRAVITATIONAL_CONSTANTfloat64=3_986_005_000_000_000
// Dynamical form factor J2; adimensional
GRS80_DYNAMICAL_FORM_FACTORfloat64=0.0108263
// Dynamical form factor ω; defined in s^-1
GRS80_ANGULAR_VELOCITYfloat64=0.0007292115
)Defining physical constants
const(
// Semi minor axis b, defined in meters (m)
GRS80_SEMI_MINOR_AXISfloat64=6_356_752.314140
// Aspect ratio (b/a); adimensional
GRS80_ASPECT_RATIOfloat64=0.996647189318816362
// Mean radius R1 = (2a+b)/3, defined in meters (m)
GRS80_MEAN_RADIUS=6_371_008.7714
// Mean radius R2, defined in meters (m)
GRS80_AUTHALIC_MEAN_RADIUS=6_371_007.1810
// Radius of a sphere of the same volume R3 = ((a^2)*b)^(1/3); defined in meters (m)
GRS80_SPHERE_RADIUS=6_371_000.7900
// Polar radius of curvature = (a^2)/b; defined in meters (m)
GRS80_POLAR_CURVATURE_RADIUS=6_399_593.6259
// Equatorial radius of curvature for a meridian = (b^2)/a; defined in meters (m)
GRS80_MERIDIAN_CURVATURE_EQUATORIAL_RADIUS=6_335_439.3271
// Meridian quadrant (meridian quarter); defined in meters (m)
// See https://en.wikipedia.org/wiki/Meridian_arc#Quarter_meridian
GRS80_MERIDIAN_QUADRANT=10_001_965.7293
// Linear eccentricity c = sqrt((a^2)-(b^2)); defined in meters (m)
GRS80_LINEAR_ECCENTRICITY=521_854.0097
// Eccentricity of elliptical section through poles e = sqrt((a^2)-(b^2))/a; adimensional
GRS80_LINEAR_ECCENTRICITY_POLES=0.0818191910435
// Flattening f; adimensional
GRS80_FLATTENINGfloat64=0.003352810681183637418
// Flattening inverse (1/f); adimensional
GRS80_FLATTENING_INVERSEfloat64=1/0.003352810681183637418
)Derived geometrical constants (all rounded)
const(
// Period of rotation (sidereal day) = 2π/ω; defined in seconds (s)
GRS80_ROTATION_PERIODfloat64=8_616.4100637
)Derived physical constants (all rounded)
const(
// Semi major axis a, defined in meters (m)
GRS80_SEMI_MAJOR_AXISfloat64=6_378_137
)Derived geometrical constants (all rounded)
const(
// WGS84_GEOCENTRIC_GRAVITATIONAL_CONSTANT Geocentric gravitational constant GM, defined in (m^3)/(s^2)
WGS84_GEOCENTRIC_GRAVITATIONAL_CONSTANTfloat64=3_986_005_000_000_000
// WGS84_DYNAMICAL_FORM_FACTOR Dynamical form factor J2; adimensional
// See https://ahrs.readthedocs.io/en/latest/wgs84.html#ahrs.utils.wgs84.WGS.dynamical_form_factor
WGS84_DYNAMICAL_FORM_FACTORfloat64=0.0010826298213129219
// WGS84_ANGULAR_VELOCITY Dynamical form factor ω; defined in s^-1
WGS84_ANGULAR_VELOCITYfloat64=0.0007292115
)Defining physical constants
const(
// WGS84_SEMI_MINOR_AXIS Semi minor axis b, defined in meters (m)
WGS84_SEMI_MINOR_AXISfloat64=6_356_752.31424518
// WGS84_ASPECT_RATIO Aspect ratio (b/a); adimensional
WGS84_ASPECT_RATIOfloat64=0.9966471893352525
// WGS84_MEAN_RADIUS Mean radius R1 = (2a+b)/3, defined in meters (m)
WGS84_MEAN_RADIUS=6_371_008.771415059
// WGS84_AUTHALIC_MEAN_RADIUS Mean radius R2, defined in meters (m)
WGS84_AUTHALIC_MEAN_RADIUS=6_371_007.1809182055
// WGS84_SPHERE_RADIUS Radius of a sphere of the same volume R3 = ((a^2)*b)^(1/3); defined in meters (m)
WGS84_SPHERE_RADIUS=6_371_000.79000916
// WGS84_POLAR_CURVATURE_RADIUS Polar radius of curvature = (a^2)/b; defined in meters (m)
WGS84_POLAR_CURVATURE_RADIUS=6_399_593.625758493
// WGS84_MERIDIAN_CURVATURE_EQUATORIAL_RADIUS Equatorial radius of curvature for a meridian = (b^2)/a; defined in meters (m)
WGS84_MERIDIAN_CURVATURE_EQUATORIAL_RADIUS=6_335_439.327292821
// WGS84_MERIDIAN_QUADRANT Meridian quadrant (meridian quarter); defined in meters (m)
// See https://en.wikipedia.org/wiki/Meridian_arc#Quarter_meridian
WGS84_MERIDIAN_QUADRANT=10_001_965.729
// WGS84_LINEAR_ECCENTRICITY Linear eccentricity c = sqrt((a^2)-(b^2)); defined in meters (m)
WGS84_LINEAR_ECCENTRICITY=521_854.0084234
// WGS84_LINEAR_ECCENTRICITY_POLES Eccentricity of elliptical section through poles e = sqrt((a^2)-(b^2))/a; adimensional
WGS84_LINEAR_ECCENTRICITY_POLES=0.0818191918426205
// WGS84_FLATTENING Flattening f; adimensional
WGS84_FLATTENINGfloat64=1/298.257223563
// WGS84_FLATTENING_INVERSE Flattening inverse (1/f); adimensional
WGS84_FLATTENING_INVERSEfloat64=298.257223563
)Defining geometrical constants
const(
// WGS84_ROTATION_PERIOD Period of rotation (sidereal day) = 2π/ω; defined in seconds (s)
WGS84_ROTATION_PERIODfloat64=8_616.4100637
)Derived physical constants (all rounded)
const(
// WGS84_SEMI_MAJOR_AXIS Semi major axis a, defined in meters (m)
WGS84_SEMI_MAJOR_AXISfloat64=6_378_137
)Defining geometrical constants