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

classDynamicDetectionTask(*args, **kwargs): Detection of sources on an image with a dynamic threshold...

attributeconfig: Access configuration fields and retargetable subtasks.

methodrun(table, exposure, doSmooth=True, sigma=None, clearMask=True, expId=None): Detect sources and return catalog(s) of detections...

Retargetable subtasks¶

background¶

Default: lsst.meas.algorithms.subtractBackground.SubtractBackgroundTask
Field type: ConfigurableField

Background re-estimation; ignored if reEstimateBackground false

skyObjects¶

Default: lsst.meas.algorithms.skyObjects.SkyObjectsTask
Field type: ConfigurableField

Generate sky objects

tempLocalBackground¶

Default: lsst.meas.algorithms.subtractBackground.SubtractBackgroundTask
Field type: ConfigurableField

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¶

Default: lsst.meas.algorithms.subtractBackground.SubtractBackgroundTask
Field type: ConfigurableField

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¶

Default: 0.0
Field type: float Field

Fiddle factor to add to the background; debugging only

combinedGrow¶

Default: True
Field type: bool Field

Grow all footprints at the same time? This allows disconnected footprints to merge.

doBackgroundTweak¶

Default: True
Field type: bool Field

Tweak background level so median PSF flux of sky objects is zero?

doTempLocalBackground¶

Default: True
Field type: bool Field

Enable temporary local background subtraction? (see tempLocalBackground)

doTempWideBackground¶

Default: False
Field type: bool Field

Do temporary wide (large-scale) background subtraction before footprint detection?

includeThresholdMultiplier¶

Default: 1.0
Field type: float RangeField
Range: [0.0,inf)

Include threshold relative to thresholdValue

isotropicGrow¶

Default: False
Field type: bool Field

Pixels should be grown as isotropically as possible (slower)

minNumSources¶

Default: 10
Field type: int Field

Minimum number of sky sources in statistical sample; if below this number, we refuse to modify the threshold.

minPixels¶

Default: 1
Field type: int RangeField
Range: [0,inf)

detected sources with fewer than the specified number of pixels will be ignored

nPeaksMaxSimple¶

Default: 1
Field type: int Field

The maximum number of peaks in a Footprint before trying to replace its peaks using the temporary local background

nSigmaForKernel¶

Default: 7.0
Field type: float Field

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¶

Default: 2.4
Field type: float Field

Grow detections by nSigmaToGrow * [PSF RMS width]; if 0 then do not grow

prelimThresholdFactor¶

Default: 0.5
Field type: float Field

Fraction of the threshold to use for first pass (to find sky objects)

reEstimateBackground¶

Default: True
Field type: bool Field

Estimate the background again after final source detection?

returnOriginalFootprints¶

Default: False
Field type: bool Field

Grow detections to set the image mask bits, but return the original (not-grown) footprints

statsMask¶

Default: ['BAD', 'SAT', 'EDGE', 'NO_DATA']
Field type: str ListField

Mask planes to ignore when calculating statistics of image (for thresholdType=stdev)

thresholdPolarity¶

Default

'positive'

Field type

str ChoiceField

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¶