GeographicLib: GeographicLib::LocalCartesian Class Reference (original) (raw)

Local cartesian coordinates. More...

#include <[GeographicLib/LocalCartesian.hpp](LocalCartesian%5F8hpp%5Fsource.html)>

Local cartesian coordinates.

Convert between geodetic coordinates latitude = lat, longitude = lon, height = h (measured vertically from the surface of the ellipsoid) to local cartesian coordinates (x, y, z). The origin of local cartesian coordinate system is at lat = lat0, lon = lon0, h = h0. The z axis is normal to the ellipsoid; the y axis points due north. The plane z = - h0 is tangent to the ellipsoid.

The conversions all take place via geocentric coordinates using a Geocentric object (by default Geocentric::WGS84()).

Example of use:

#include

#include

#include

using namespace std;

try {

Geocentric earth(Constants::WGS84_a(), Constants::WGS84_f());

const double lat0 = 48 + 50/60.0, lon0 = 2 + 20/60.0;

{

double lat = 50.9, lon = 1.8, h = 0;

double x, y, z;

proj.Forward(lat, lon, h, x, y, z);

cout << x << " " << y << " " << z << "\n";

}

{

double x = -38e3, y = 230e3, z = -4e3;

double lat, lon, h;

proj.Reverse(x, y, z, lat, lon, h);

cout << lat << " " << lon << " " << h << "\n";

}

}

catch (const exception& e) {

cerr << "Caught exception: " << e.what() << "\n";

return 1;

}

}

int main(int argc, const char *const argv[])

Header for GeographicLib::Geocentric class.

Header for GeographicLib::LocalCartesian class.

Local cartesian coordinates.

Namespace for GeographicLib.

CartConvert is a command-line utility providing access to the functionality of Geocentric and LocalCartesian.

Definition at line 38 of file LocalCartesian.hpp.

Constructor setting the origin.

Parameters

lat0 should be in the range [−90°, 90°].

Definition at line 64 of file LocalCartesian.hpp.

◆ LocalCartesian() [2/2]

Default constructor.

Parameters

Sets lat0 = 0, lon0 = 0, h0 = 0.

Definition at line 77 of file LocalCartesian.hpp.

◆ Reset()

◆ Forward() [1/2]

Convert from geodetic to local cartesian coordinates.

Parameters

lat should be in the range [−90°, 90°].

Definition at line 104 of file LocalCartesian.hpp.

Referenced by main().

◆ Forward() [2/2]

Convert from geodetic to local cartesian coordinates and return rotation matrix.

Parameters

lat should be in the range [−90°, 90°].

Let v be a unit vector located at (lat, lon, h). We can express v as column vectors in one of two ways

• in east, north, up coordinates (where the components are relative to a local coordinate system at (lat, lon, h)); call this representation v1.
• in x, y, z coordinates (where the components are relative to the local coordinate system at (lat0, lon0, h0)); call this representation v0.

Then we have v0 = M ⋅ v1.

Definition at line 135 of file LocalCartesian.hpp.

◆ Reverse() [1/2]

Convert from local cartesian to geodetic coordinates.

Parameters

In general, there are multiple solutions and the result which minimizes |h |is returned, i.e., (lat, lon) corresponds to the closest point on the ellipsoid. The value of lon returned is in the range [−180°, 180°].

Definition at line 161 of file LocalCartesian.hpp.

Referenced by main().

◆ Reverse() [2/2]

Convert from local cartesian to geodetic coordinates and return rotation matrix.

Parameters

Let v be a unit vector located at (lat, lon, h). We can express v as column vectors in one of two ways

• in east, north, up coordinates (where the components are relative to a local coordinate system at (lat, lon, h)); call this representation v1.
• in x, y, z coordinates (where the components are relative to the local coordinate system at (lat0, lon0, h0)); call this representation v0.

Then we have v1 = _M_T ⋅ v0, where _M_T is the transpose of M.

Definition at line 191 of file LocalCartesian.hpp.

◆ LatitudeOrigin()

◆ LongitudeOrigin()

◆ HeightOrigin()

◆ EquatorialRadius()

◆ Flattening()

The documentation for this class was generated from the following files:

• LocalCartesian.hpp
• LocalCartesian.cpp