surf_pos_from_surf_coord

Ellipsoid.surf_pos_from_surf_coord(self, lat: double | ndarray[double], lon: double | ndarray[double]) → ndarray[double]

Compute the ECEF surface position vector(s) on the reference ellipsoid.

Given a scalar or 1-D array of geodetic latitudes \(\phi\) and longitudes \(\lambda\) (in radians, SI), return the corresponding surface radius vector(s) in Earth-Centered, Earth-Fixed (ECEF) coordinates.

Parameters:

latfloat or ndarray of float, shape (N,)

Geodetic latitude(s) \(\phi\) in radians.

lonfloat or ndarray of float, shape (N,)

Geodetic longitude(s) \(\lambda\) in radians.

Returns:

r_surfndarray of float, shape (3,) or (N, 3)

Surface position vector(s) \(\mathbf{r}\) in metres. - If both lat and lon are scalars, returns a 1-D array

of length 3: [x, y, z].

• If they are 1-D arrays of length N, returns an (N × 3) array where each row is [x, y, z].

Raises:

AssertionError

If lat and lon are arrays with differing shapes.

See also

c_r_surf

Core C implementation (nogil) computing a single r_surf.

Notes

Internally dispatches to the low-level C function c_r_surf for each point, releasing the GIL.

\[\mathbf{r}(\phi,\lambda) = egin{bmatrix} N(\phi)\cos\phi\cos\lambda \[6pt] N(\phi)\cos\phi\sin\lambda \[6pt] igl(N(\phi)\,(1 - e^2)igr)\sin\phi \end{bmatrix},\]

where

\[N(\phi) = \]

rac{a}{sqrt{1 - e^2,sin^2phi}}