def locdir_at(self, phi, theta, psi, row, col, alt=0, geo=True):
"""
Given the satellite attitude, computes lon, lat of point row, col, alt.
Args:
phi, theta, psi: attitude angles of the satellite camera
row, col: pixel coordinates in the image plane
alt: altitude of the 3d point above the Earth surface
geo: boolean flag telling whether to return geographic
coordinates or Cartesian coordinates.
Returns:
geographic coordinates (lon, lat), or Cartesian coordinates
(x, y, z). Cartesian coordinates are computed with respect to the
orbital frame.
"""
# first compute coordinates of the 3-space point in the orbital frame
orbital_to_camera = utils.rotation_3d('xyz', phi, theta, psi)
v = np.dot(orbital_to_camera, self.instrument.sight_vector(col))
c = np.array([0, 0, self.orbit.radius])
r = PhysicalConstants.earth_radius + alt
p = utils.intersect_line_and_sphere(v, c, r)
if not geo:
return p
# then convert them to lon, lat, using t to get the satellite position
if p is None:
return p
else:
t = row * self.instrument.dwell_time
mat_t_ol = self.rotational_to_orbital(t)
return utils.lon_lat(np.dot(mat_t_ol, -c + p))
def locdir_at(self, phi, theta, psi, row, col, alt=0, geo=True):
"""
Given the satellite attitude, computes lon, lat of point row, col, alt.
Args:
phi, theta, psi: attitude angles of the satellite camera
row, col: pixel coordinates in the image plane
alt: altitude of the 3d point above the Earth surface
geo: boolean flag telling whether to return geographic
coordinates or Cartesian coordinates.
Returns:
geographic coordinates (lon, lat), or Cartesian coordinates
(x, y, z). Cartesian coordinates are computed with respect to the
orbital frame.
"""
# first compute coordinates of the 3-space point in the orbital frame
orbital_to_camera = utils.rotation_3d('xyz', phi, theta, psi)
v = np.dot(orbital_to_camera, self.instrument.sight_vector(col))
c = np.array([0, 0, self.orbit.radius])
r = PhysicalConstants.earth_radius + alt
p = utils.intersect_line_and_sphere(v, c, r)
if not geo:
return p
# then convert them to lon, lat, using t to get the satellite position
if p is None:
return p
else:
t = row * self.instrument.dwell_time
mat_t_ol = self.rotational_to_orbital(t)
return utils.lon_lat(np.dot(mat_t_ol, -c + p))
def pushbroom_direction_on_the_ground(self, cap, p, t):
"""
Computes the projection of the pushbroom direction on the ground.
Args:
cap: direction of the pushbroom array movement, on the ground, in
degrees. North is 0, Sud is 180 and East is 90.
p: orbital coordinates of the ground point currently targeted
t: time elapsed since the beginning of the acquisition, in seconds
Returns:
the orbital coordinates of a vector giving the pushbroom movement
direction, projected on the ground.
"""
# coordinates of the Earth center in the orbital frame
c = np.array([0, 0, self.orbit.radius])
# direction of the pushbroom movement, projected on the ground, in
# local geographic coordinates (z, easting, northing)
v = np.array([0, np.sin(cap * np.pi/180), np.cos(cap * np.pi/180)])
# convert v from local geographic coordinates to orbital coordinates
rot_to_orb = self.rotational_to_orbital(t)
p_rot = np.dot(rot_to_orb, -c + p)
lon, lat = utils.lon_lat(p_rot)
rot_to_geo = utils.rotational_to_local_geographic(lon, lat)
return np.dot(rot_to_orb.T, np.dot(rot_to_geo, v))
def pushbroom_direction_on_the_ground(self, cap, p, t):
"""
Computes the projection of the pushbroom direction on the ground.
Args:
cap: direction of the pushbroom array movement, on the ground, in
degrees. North is 0, Sud is 180 and East is 90.
p: orbital coordinates of the ground point currently targeted
t: time elapsed since the beginning of the acquisition, in seconds
Returns:
the orbital coordinates of a vector giving the pushbroom movement
direction, projected on the ground.
"""
# coordinates of the Earth center in the orbital frame
c = np.array([0, 0, self.orbit.radius])
# direction of the pushbroom movement, projected on the ground, in
# local geographic coordinates (z, easting, northing)
v = np.array([0, np.sin(cap * np.pi / 180), np.cos(cap * np.pi / 180)])
# convert v from local geographic coordinates to orbital coordinates
rot_to_orb = self.rotational_to_orbital(t)
p_rot = np.dot(rot_to_orb, -c + p)
lon, lat = utils.lon_lat(p_rot)
rot_to_geo = utils.rotational_to_local_geographic(lon, lat)
return np.dot(rot_to_orb.T, np.dot(rot_to_geo, v))