def ecef_from_topocentric_transform_finite_diff()

in metropolis/utils/geo.py [0:0]

• 38 lines of code
• 1 McCabe index (conditional complexity)

def ecef_from_topocentric_transform_finite_diff(lat, lon, alt):
    """
    Transformation from a topocentric frame at reference position to ECEF.

    The topocentric reference frame is a metric one with the origin
    at the given (lat, lon, alt) position, with the X axis heading east,
    the Y axis heading north and the Z axis vertical to the ellipsoid.
    """
    eps = 1e-2
    x, y, z = ecef_from_lla(lat, lon, alt)
    v1 = (
        (
            np.array(ecef_from_lla(lat, lon + eps, alt))
            - np.array(ecef_from_lla(lat, lon - eps, alt))
        )
        / 2
        / eps
    )
    v2 = (
        (
            np.array(ecef_from_lla(lat + eps, lon, alt))
            - np.array(ecef_from_lla(lat - eps, lon, alt))
        )
        / 2
        / eps
    )
    v3 = (
        (
            np.array(ecef_from_lla(lat, lon, alt + eps))
            - np.array(ecef_from_lla(lat, lon, alt - eps))
        )
        / 2
        / eps
    )
    v1 /= np.linalg.norm(v1)
    v2 /= np.linalg.norm(v2)
    v3 /= np.linalg.norm(v3)
    return np.array(
        [
            [v1[0], v2[0], v3[0], x],
            [v1[1], v2[1], v3[1], y],
            [v1[2], v2[2], v3[2], z],
            [0, 0, 0, 1],
        ]
    )