DynamicDetectionTask¶
DynamicDetectionTask detects sources on an image with a dynamic threshold.
Processing summary¶
DynamicDetectionTask runs this sequence of operations:
Detects sources using a lower threshold than normal in order to identify good sky regions.
Performs forced PSF photometry on identified sky regions.
Sets threshold so that the standard deviation of measurements matches median estimated error using PSF flux measurements and estimated errors.
Python API summary¶
from lsst.meas.algorithms.dynamicDetection import DynamicDetectionTask
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class
DynamicDetectionTask(*args, **kwargs) Detection of sources on an image with a dynamic threshold
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- attributeconfig
Access configuration fields and retargetable subtasks.
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method
run(table, exposure, doSmooth=True, sigma=None, clearMask=True, expId=None) Run source detection and create a SourceCatalog of detections
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See also
See the DynamicDetectionTask API reference for complete details.
Retargetable subtasks¶
background¶
Background re-estimation; ignored if reEstimateBackground false
skyObjects¶
- Default
- Field type
Generate sky objects
tempLocalBackground¶
A local (small-scale), temporary background estimation step run between detecting above-threshold regions and detecting the peaks within them; used to avoid detecting spuerious peaks in the wings.
tempWideBackground¶
A wide (large-scale) background estimation and removal before footprint and peak detection. It is added back into the image after detection. The purpose is to suppress very large footprints (e.g., from large artifacts) that the deblender may choke on.
Configuration fields¶
adjustBackground¶
Fiddle factor to add to the background; debugging only
combinedGrow¶
Grow all footprints at the same time? This allows disconnected footprints to merge.
doBackgroundTweak¶
Tweak background level so median PSF flux of sky objects is zero?
doTempLocalBackground¶
Enable temporary local background subtraction? (see tempLocalBackground)
doTempWideBackground¶
Do temporary wide (large-scale) background subtraction before footprint detection?
includeThresholdMultiplier¶
- Default
1.0- Field type
- Range
[0.0,inf)
Include threshold relative to thresholdValue
isotropicGrow¶
Pixels should be grown as isotropically as possible (slower)
minNumSources¶
Minimum number of sky sources in statistical sample; if below this number, we refuse to modify the threshold.
minPixels¶
- Default
1- Field type
- Range
[0,inf)
detected sources with fewer than the specified number of pixels will be ignored
nPeaksMaxSimple¶
The maximum number of peaks in a Footprint before trying to replace its peaks using the temporary local background
nSigmaForKernel¶
Multiple of PSF RMS size to use for convolution kernel bounding box size; note that this is not a half-size. The size will be rounded up to the nearest odd integer
nSigmaToGrow¶
Grow detections by nSigmaToGrow * [PSF RMS width]; if 0 then do not grow
prelimThresholdFactor¶
Fraction of the threshold to use for first pass (to find sky objects)
reEstimateBackground¶
Estimate the background again after final source detection?
returnOriginalFootprints¶
Grow detections to set the image mask bits, but return the original (not-grown) footprints
statsMask¶
Mask planes to ignore when calculating statistics of image (for thresholdType=stdev)
thresholdPolarity¶
- Default
'positive'- Field type
- Choices
'positive'detect only positive sources
'negative'detect only negative sources
'both'detect both positive and negative sources
specifies whether to detect positive, or negative sources, or both
thresholdType¶
- Default
'stdev'- Field type
- Choices
'variance'threshold applied to image variance
'stdev'threshold applied to image std deviation
'value'threshold applied to image value
'pixel_stdev'threshold applied to per-pixel std deviation
specifies the desired flavor of Threshold
thresholdValue¶
- Default
5.0- Field type
- Range
[0.0,inf)
Threshold for footprints; exact meaning and units depend on thresholdType.