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DM-52677: Add functors for trailLengthErr and trailAngleErr #1237

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3468200
Add ConvertDetectorAngleErrToPositionAngleErr Functor
bsmartradio Oct 10, 2025
95b2123
Test position angle error prop
bsmartradio Oct 16, 2025
bc6bbd5
Fix
bsmartradio Oct 16, 2025
d197992
Fix functor
bsmartradio Oct 17, 2025
971a918
Test new functor
bsmartradio Oct 24, 2025
0397500
Without debuging
bsmartradio Oct 24, 2025
2135770
Logging for testing
bsmartradio Oct 24, 2025
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96 changes: 96 additions & 0 deletions python/lsst/pipe/tasks/functors.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1394,6 +1394,55 @@ def getPositionAngleFromDetectorAngle(self, theta, cd11, cd12, cd21, cd22):
# Position angle of vector from (RA1, Dec1) to (RA2, Dec2)
return np.rad2deg(self.computePositionAngle(ra1, dec1, ra2, dec2))

def getPositionAngleErrFromDetectorAngleErr(self, theta, theta_err, cd11, cd12, cd21, cd22):
"""Compute position angle error (E of N) from detector angle error.

Parameters
----------
theta : `float`
detector angle [radian]
theta_err : `float`
detector angle err [radian]
cd11 : `float`
[1, 1] element of the local Wcs affine transform.
cd12 : `float`
[1, 2] element of the local Wcs affine transform.
cd21 : `float`
[2, 1] element of the local Wcs affine transform.
cd22 : `float`
[2, 2] element of the local Wcs affine transform.
Returns
-------
Position Angle Error: `~pandas.Series`
Position angle error in degrees
"""
# Need to compute abs(dPA/dtheta)*theta_Err to get propogated errors

# Get unit direction
dx = np.cos(theta)
dy = np.sin(theta)

# Transform it using WCS?
u = dx * cd11 + dy * cd12
v = dx * cd21 + dy * cd22
# Now we are computing the tangent
ratio = u / v

# Get derivative of theta
du_dtheta = -np.sin(theta) * cd11 + np.cos(theta) * cd12
dv_dtheta = -np.sin(theta) * cd21 + np.cos(theta) * cd22

# Get derivative of tangent
d_ratio_dtheta = (v * du_dtheta - u * dv_dtheta) / v ** 2
dPA_dtheta = (1 / (1 + ratio ** 2)) * d_ratio_dtheta

pa_err = np.rad2deg(np.abs(dPA_dtheta) * theta_err)

logging.info("PA Error: %s" % pa_err)
logging.info("theta_err: %s" % theta_err)

return pa_err


class ComputePixelScale(LocalWcs):
"""Compute the local pixel scale from the stored CDMatrix.
Expand Down Expand Up @@ -1554,6 +1603,53 @@ def _func(self, df):
)


class ConvertDetectorAngleErrToPositionAngleErr(LocalWcs):
"""Compute a position angle error from a detector angle error and the
stored CDMatrix.

Returns
-------
position angle error : degrees
"""

name = "PositionAngleErr"

def __init__(
self,
theta_col,
theta_err_col,
colCD_1_1,
colCD_1_2,
colCD_2_1,
colCD_2_2,
**kwargs
):
self.theta_col = theta_col
self.theta_err_col = theta_err_col
super().__init__(colCD_1_1, colCD_1_2, colCD_2_1, colCD_2_2, **kwargs)

@property
def columns(self):
return [
self.theta_col,
self.theta_err_col,
self.colCD_1_1,
self.colCD_1_2,
self.colCD_2_1,
self.colCD_2_2
]

def _func(self, df):
return self.getPositionAngleErrFromDetectorAngleErr(
df[self.theta_col],
df[self.theta_err_col],
df[self.colCD_1_1],
df[self.colCD_1_2],
df[self.colCD_2_1],
df[self.colCD_2_2]
)


class ReferenceBand(Functor):
"""Return the band used to seed multiband forced photometry.

Expand Down
67 changes: 65 additions & 2 deletions tests/test_functors.py
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Original file line number Diff line number Diff line change
Expand Up @@ -49,11 +49,10 @@
ConvertDetectorAngleToPositionAngle,
HtmIndex20, Ebv, MomentsIuuSky, MomentsIvvSky, MomentsIuvSky,
SemimajorAxisFromMoments, SemiminorAxisFromMoments,
PositionAngleFromMoments,
CorrelationIuuSky, CorrelationIvvSky, CorrelationIuvSky,
SemimajorAxisFromCorrelation, SemiminorAxisFromCorrelation,
PositionAngleFromCorrelation
)
PositionAngleFromMoments, ConvertDetectorAngleErrToPositionAngleErr)

Check failure on line 55 in tests/test_functors.py

View workflow job for this annotation

GitHub Actions / call-workflow / lint

E999 

SyntaxError: invalid syntax

ROOT = os.path.abspath(os.path.dirname(__file__))

Expand Down Expand Up @@ -762,6 +761,70 @@

np.testing.assert_allclose(coord_diff, 0, rtol=0, atol=5e-6)

# Test position angle error propogation
def testConvertDetectorAngleErrToPositionAngleErr(self):
"""Test conversion of position angle err in detector degrees to
position angle erron sky
"""
dipoleSep = 10
ixx = 10
testPixelDeltas = np.random.uniform(-100, 100, size=(self.nRecords, 2))
# testConvertPixelToArcSecond uses a meas_base LocalWcsPlugin
# but we're using a simple WCS as our example, so this doesn't really matter
# and we'll just use the WCS directly
for dec in np.linspace(-90, 90, 10):
for theta in (-45, 0, 90):
for x, y in zip(np.random.uniform(2 * 1109.99981456774, size=10),
np.random.uniform(2 * 560.018167811613, size=10)):
wcs = self._makeWcs(dec=dec, theta=theta)
cd_matrix = wcs.getCdMatrix()

self.dataDict["dipoleSep"] = np.full(self.nRecords, dipoleSep)
self.dataDict["ixx"] = np.full(self.nRecords, ixx)
self.dataDict["slot_Centroid_x"] = np.full(self.nRecords, x)
self.dataDict["slot_Centroid_y"] = np.full(self.nRecords, y)
self.dataDict["someCentroid_x"] = x + testPixelDeltas[:, 0]
self.dataDict["someCentroid_y"] = y + testPixelDeltas[:, 1]
self.dataDict["orientation"] = np.arctan2(
self.dataDict["someCentroid_y"] - self.dataDict["slot_Centroid_y"],
self.dataDict["someCentroid_x"] - self.dataDict["slot_Centroid_x"],
)
self.dataDict["orientation_err"] = np.arctan2(
self.dataDict["someCentroid_y"] - self.dataDict[ "slot_Centroid_y"],
self.dataDict["someCentroid_x"] - self.dataDict["slot_Centroid_x"],
)*.001

self.dataDict["base_LocalWcs_CDMatrix_1_1"] = np.full(self.nRecords,
cd_matrix[0, 0])
self.dataDict["base_LocalWcs_CDMatrix_1_2"] = np.full(self.nRecords,
cd_matrix[0, 1])
self.dataDict["base_LocalWcs_CDMatrix_2_1"] = np.full(self.nRecords,
cd_matrix[1, 0])
self.dataDict["base_LocalWcs_CDMatrix_2_2"] = np.full(self.nRecords,
cd_matrix[1, 1])
df = self.getMultiIndexDataFrame(self.dataDict)

# Test detector angle to position angle conversion
func = ConvertDetectorAngleErrToPositionAngleErr(
"orientation",
"orientation_err",
"base_LocalWcs_CDMatrix_1_1",
"base_LocalWcs_CDMatrix_1_2",
"base_LocalWcs_CDMatrix_2_1",
"base_LocalWcs_CDMatrix_2_2"
)

func_pa = ConvertDetectorAngleToPositionAngle(
"orientation",
"base_LocalWcs_CDMatrix_1_1",
"base_LocalWcs_CDMatrix_1_2",
"base_LocalWcs_CDMatrix_2_1",
"base_LocalWcs_CDMatrix_2_2"
)
val = self._funcVal(func, df)
val_pa = self._funcVal(func_pa, df)


def testConvertPixelToArcseconds(self):
"""Test calculations of the pixel scale, conversions of pixel to
arcseconds.
Expand Down
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