def focus_surface(self, surface_to_move: SurfaceData,
previous_surface: SurfaceData) -> None:
"""
move the location of a surface to the closest approach to the target position
given by the user in the configuration file
:param surface_to_move: the surface that will be moved
:param previous_surface: the surface previous to the surface being moved
:return:
"""
self.focus_found = True
# flag surface as being focused
surface_to_move.target_focused = True
# surface_to_move.surface_type = 4
# get position of target
lla_target = np.asarray([
self.cnf.surface_focusing_lat, self.cnf.surface_focusing_lon,
self.cnf.surface_focusing_alt
])
pos_target = lla2ecef(lla_target, self.cst)
# get current position of focus surface & previous
pos_focus = np.asmatrix(surface_to_move.ecef_surf)
pos_prior = np.asmatrix(previous_surface.ecef_surf)
# calculate along-track direction vector
along_track = pos_focus - pos_prior
along_track /= np.linalg.norm(along_track)
# calculate vector from previous surface to target position
rel_target = pos_target - pos_prior
# project relative target vector onto along-track direction
cos_a = (along_track * rel_target.T) / np.linalg.norm(rel_target)
rel_focus = (np.linalg.norm(rel_target) * cos_a) * along_track
# get position to move surface to
x_move, y_move, z_move = np.ravel(rel_focus)
focus_x = previous_surface.x_surf + x_move
focus_y = previous_surface.y_surf + y_move
focus_z = previous_surface.z_surf + z_move
focus_ecef = np.asarray([focus_x, focus_y, focus_z])
# set new position of focus surface
surface_to_move.x_surf = focus_x
surface_to_move.y_surf = focus_y
surface_to_move.z_surf = focus_z
focus_lla = ecef2lla(focus_ecef, self.cst)
focus_lat, focus_lon, focus_alt = np.ravel(focus_lla)
surface_to_move.lat_surf = focus_lat
surface_to_move.lon_surf = focus_lon
surface_to_move.alt_surf = focus_alt
surface_to_move.win_delay_surf =\
(surface_to_move.alt_sat - surface_to_move.alt_surf) * 2. / self.cst.c
