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Imu fix chart orientation #416

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Imu fix chart orientation #416

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d76ec1c
Fix: Horizontal coordinate orientation (use -parallactic_angle)
Apr 30, 2026
848ef57
Remove duplicate definition of dt
May 1, 2026
29cd601
Encapsulate functionality to set Alt, Az, Roll in solved dict to a func
May 1, 2026
f53401a
1) Ensure that AltAz is calculated when plate solved. 2) Fall back to…
May 1, 2026
b898825
Fix: No need to add 180 deg to -parallactic_angle for horizontal coor…
May 2, 2026
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19 changes: 19 additions & 0 deletions python/PiFinder/calc_utils.py
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Original file line number Diff line number Diff line change
Expand Up @@ -388,6 +388,25 @@ def ra_to_ha(self, ra_deg, dt):

return ha_hrs * 180 / 12 # Hour angle [deg]

def radec_to_pa(self, ra_deg, dec_deg, dt):
"""
Returns the parallactic angle of an object at (ra, dec) as seen from an
observer at latitiude, lat and time, dt. See hadec_to_pa() for how
parallactic angle is defined.

INPUTS:
ra_deg: Right ascension [deg]
dec_deg: Declination [deg]
dt: Python datetime object (must be timezone-aware)

RETURNS:
pa_deg: Parallactic angle [deg]
"""
ha_deg = self.ra_to_ha(ra_deg, dt) # Note that HA is in deg
lat_deg = self._observer_geoid.latitude.degrees
pa_deg = hadec_to_pa(ha_deg, dec_deg, lat_deg)
return pa_deg # Parallactic angle [deg]

def radec_to_roll(self, ra_deg, dec_deg, dt):
"""
Returns the roll (field rotation) of an object at (ra, dec) as
Expand Down
116 changes: 61 additions & 55 deletions python/PiFinder/integrator.py
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Original file line number Diff line number Diff line change
Expand Up @@ -62,9 +62,10 @@ def integrator(shared_state, solver_queue, console_queue, log_queue, is_debug=Fa
# This holds the last image solve position info
# so we can delta for IMU updates
last_image_solve = None
last_solve_time = time.time()
#last_solve_time = time.time()

while True:
pointing_updated = False # Flag to track if pointing was updated in this loop
state_utils.sleep_for_framerate(shared_state)

# Check for new camera solve in queue
Expand All @@ -75,6 +76,7 @@ def integrator(shared_state, solver_queue, console_queue, log_queue, is_debug=Fa
pass

if type(next_image_solve) is dict:
# TODO: Refactor this bit:
# For camera solves, always start from last successful camera solve
# NOT from shared_state (which may contain IMU drift)
# This prevents IMU noise accumulation during failed solves
Expand All @@ -100,20 +102,17 @@ def integrator(shared_state, solver_queue, console_queue, log_queue, is_debug=Fa
# For failed solves, preserve ALL position data from previous solve
# Don't recalculate from GPS (causes drift from GPS noise)

# Set solve_source and push camera solves immediately
if solved["RA"] is not None:
# Successfully plate-solved:
last_image_solve = copy.deepcopy(solved)
solved["solve_source"] = "CAM"
# Calculate constellation for successful solve
solved["constellation"] = (
calc_utils.sf_utils.radec_to_constellation(
solved["RA"], solved["Dec"]
)
)
shared_state.set_solve_state(True)
# We have a new image solve: Use plate-solving for RA/Dec
update_plate_solve_and_imu(imu_dead_reckoning, solved)
#last_solve_time = solved["solve_time"]
pointing_updated = True
else:
# TODO: In this case, it should run update_imu()
# Failed solve - clear constellation
solved["solve_source"] = "CAM_FAILED"
solved["constellation"] = ""
Expand All @@ -123,50 +122,26 @@ def integrator(shared_state, solver_queue, console_queue, log_queue, is_debug=Fa
shared_state.set_solution(solved)
shared_state.set_solve_state(False)

elif imu_dead_reckoning.tracking:
if imu_dead_reckoning.tracking and not pointing_updated:
# Previous plate-solve exists so use IMU dead-reckoning from
# the last plate solved coordinates.
imu = shared_state.imu()
if imu:
#last_solve_time = time.time()
update_imu(imu_dead_reckoning, solved, last_image_solve, imu)
pointing_updated = True

# Push IMU updates only if newer than last push
if (
solved["RA"] and solved["solve_time"] > last_solve_time
# and solved["solve_source"] == "IMU"
):
last_solve_time = time.time() # TODO: solve_time is ambiguous because it's also used for IMU dead-reckoning

# Update Alt, Az, Roll only if newer than last push
if pointing_updated:
#last_solve_time = time.time()
# Set location for roll and altaz calculations.
# TODO: Is it necessary to set location?
# TODO: Altaz doesn't seem to be required for catalogs when in
# EQ mode? Could be disabled in future when in EQ mode?
location = shared_state.location()
dt = shared_state.datetime()
if location:
calc_utils.sf_utils.set_location(
location.lat, location.lon, location.altitude
)

# Set the roll so that the chart is displayed appropriately for the mount type
solved["Roll"] = get_roll_by_mount_type(
solved["RA"], solved["Dec"], location, dt, mount_type
)

# Update remaining solved keys
# Calculate constellation for current position
solved["constellation"] = calc_utils.sf_utils.radec_to_constellation(
solved["RA"], solved["Dec"]
) # TODO: Can the outer brackets be omitted?

# Set Alt/Az because it's needed for the catalogs for the
# Alt/Az mount type. TODO: Can this be moved to the catalog?
dt = shared_state.datetime()
if location and dt:
solved["Alt"], solved["Az"] = calc_utils.sf_utils.radec_to_altaz(
solved["RA"], solved["Dec"], dt
)

update_solved_coords(solved,
location=shared_state.location(),
dt=shared_state.datetime(),
mount_type=mount_type)
# Push IMU update
shared_state.set_solution(solved)
shared_state.set_solve_state(True)
Expand All @@ -177,7 +152,6 @@ def integrator(shared_state, solver_queue, console_queue, log_queue, is_debug=Fa

# ======== Wrapper and helper functions ===============================


def update_plate_solve_and_imu(imu_dead_reckoning: ImuDeadReckoning, solved: dict):
"""
Wrapper for ImuDeadReckoning.update_plate_solve_and_imu() to
Expand Down Expand Up @@ -275,6 +249,36 @@ def update_imu(
)


def update_solved_coords(solved, location, dt, mount_type):
"""
Based on RA/Dec, update the following in dictionary 'solved':
solved["Alt"], solved["Az"], solved["Roll"], solved["constellation"]
"""
if solved["RA"] is None or solved["Dec"] is None:
solved["constellation"] = None
solved["Alt"], solved["Az"] = None, None
solved["Roll"] = None
return

# Calculate constellation for current position
solved["constellation"] = calc_utils.sf_utils.radec_to_constellation(
solved["RA"], solved["Dec"]
)

if location and dt:
# Location needs to be set for Alt/Az and roll calculations
calc_utils.sf_utils.set_location(location.lat, location.lon, location.altitude)
# Set Alt/Az
solved["Alt"], solved["Az"] = calc_utils.sf_utils.radec_to_altaz(
solved["RA"], solved["Dec"], dt)
# Set the roll so that the chart is displayed appropriately for the mount type
solved["Roll"] = get_roll_by_mount_type(
solved["RA"], solved["Dec"], location, dt, mount_type)
else:
solved["Alt"], solved["Az"] = None, None
solved["Roll"] = None


def set_cam2scope_alignment(imu_dead_reckoning: ImuDeadReckoning, solved: dict):
"""
Set alignment.
Expand Down Expand Up @@ -319,6 +323,7 @@ def get_roll_by_mount_type(
if mount_type == "Alt/Az":
# Altaz mounts: Display chart in horizontal coordinates
if location and dt:
"""
# We have location and time/date (and assume that location has been set)
# Roll at the target RA/Dec in the horizontal frame
roll_deg = calc_utils.sf_utils.radec_to_roll(ra_deg, dec_deg, dt)
Expand All @@ -332,21 +337,22 @@ def get_roll_by_mount_type(
roll_deg - np.sign(ha_deg) * 180
) # In essence, gives: roll_deg = -pa_deg
# End of HACK
"""
# chart.py uses roll to rotate the chart around the target center
# by roll in anti-clockwise direction. Use -parallactic_angle
roll_deg = -calc_utils.sf_utils.radec_to_pa(ra_deg, dec_deg, dt)
else:
# No position or time/date available, so set roll to 0.0
roll_deg = 0.0
# No position or time/date available. Default to display in equatorial coordinate
roll_deg = 0.0 # NCP up
elif mount_type == "EQ":
# EQ-mounts: Display chart with NCP up so roll = 0.0
roll_deg = 0.0
# EQ-mounts: Display chart in equatorial coordinates
roll_deg = 0.0 # NCP up
# If location is available, adjust roll for hemisphere:
if location:
if location.lat < 0.0:
roll_deg = 180.0 # SCP up (for southern hemisphere)
else:
logger.error(f"Unknown mount type: {mount_type}. Cannot set roll.")
roll_deg = 0.0

# If location is available, adjust roll for hemisphere:
# Altaz: North up in northern hemisphere, South up in southern hemisphere
# EQ mounts: NCP up in northern hemisphere, SCP up in southern hemisphere
if location:
if location.lat < 0.0:
roll_deg += 180.0 # Southern hemisphere
roll_deg = 0.0 # NCP up

return roll_deg
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