Merge pull request #367 from lsst/tickets/DM-47901

DM-47901: Configure streak masking for ComCam

python/lsst/ip/diffim/detectAndMeasure.py

@@ -121,6 +121,10 @@ class DetectAndMeasureConfig(pipeBase.PipelineTaskConfig,
         target=SourceDetectionTask,
         doc="Final source detection for diaSource measurement",
     )
+    streakDetection = pexConfig.ConfigurableField(
+        target=SourceDetectionTask,
+        doc="Separate source detection used only for streak masking",
+    )
     deblend = pexConfig.ConfigurableField(
         target=lsst.meas.deblender.SourceDeblendTask,
         doc="Task to split blended sources into their components."
@@ -217,6 +221,29 @@ def setDefaults(self):
                                             "NO_DATA",
                                             ]
 
+        # Copy configs for binned streak detection from the base detection task
+        self.streakDetection.thresholdType = self.detection.thresholdType
+        self.streakDetection.reEstimateBackground = self.detection.reEstimateBackground
+        self.streakDetection.excludeMaskPlanes = self.detection.excludeMaskPlanes
+        self.streakDetection.thresholdValue = self.detection.thresholdValue
+        # Only detect positive streaks
+        self.streakDetection.thresholdPolarity = "positive"
+        # Do not grow detected mask for streaks
+        self.streakDetection.nSigmaToGrow = 0
+        # Set the streak mask along the entire fit line, not only where the
+        # detected mask is set.
+        self.maskStreaks.onlyMaskDetected = False
+        # Restrict streak masking from growing too large
+        self.maskStreaks.maxStreakWidth = 100
+        # Restrict the number of iterations allowed for fitting streaks
+        # When the fit is good it should solve quickly, and exit a bad fit quickly
+        self.maskStreaks.maxFitIter = 10
+        # Only mask to 2 sigma in width
+        self.maskStreaks.nSigmaMask = 2
+        # Threshold for including streaks after the Hough Transform.
+        # A lower value will detect more features that are less linear.
+        self.maskStreaks.absMinimumKernelHeight = 2
+
         self.measurement.plugins.names |= ["ext_trailedSources_Naive",
                                            "base_LocalPhotoCalib",
                                            "base_LocalWcs",
@@ -240,10 +267,6 @@ def setDefaults(self):
             "STREAK", "INJECTED", "INJECTED_TEMPLATE"]
         self.skySources.avoidMask = ["DETECTED", "DETECTED_NEGATIVE", "BAD", "NO_DATA", "EDGE"]
 
-        # Set the streak mask along the entire fit line, not only where the
-        # detected mask is set.
-        self.maskStreaks.onlyMaskDetected = False
-
 
 class DetectAndMeasureTask(lsst.pipe.base.PipelineTask):
     """Detect and measure sources on a difference image.
@@ -295,6 +318,7 @@ def __init__(self, **kwargs):
             self.makeSubtask("skySources", schema=self.schema)
         if self.config.doMaskStreaks:
             self.makeSubtask("maskStreaks")
+            self.makeSubtask("streakDetection")
 
         # Check that the schema and config are consistent
         for flag in self.config.badSourceFlags:
@@ -702,10 +726,13 @@ def _runStreakMasking(self, difference):
                                              self.config.streakBinFactor)
         binnedExposure = afwImage.ExposureF(binnedMaskedImage.getBBox())
         binnedExposure.setMaskedImage(binnedMaskedImage)
-        binnedExposure.setPsf(difference.psf)  # exposure must have a PSF
+        # Clear the DETECTED mask plane before streak detection
+        binnedExposure.mask &= ~binnedExposure.mask.getPlaneBitMask('DETECTED')
         # Rerun detection to set the DETECTED mask plane on binnedExposure
-        _table = afwTable.SourceTable.make(self.schema)
-        self.detection.run(table=_table, exposure=binnedExposure, doSmooth=True)
+        sigma = difference.psf.computeShape(difference.psf.getAveragePosition()).getDeterminantRadius()
+        _table = afwTable.SourceTable.make(afwTable.SourceTable.makeMinimalSchema())
+        self.streakDetection.run(table=_table, exposure=binnedExposure, doSmooth=True,
+                                 sigma=sigma/self.config.streakBinFactor)
         binnedDetectedMaskPlane = binnedExposure.mask.array & binnedExposure.mask.getPlaneBitMask('DETECTED')
         rescaledDetectedMaskPlane = binnedDetectedMaskPlane.repeat(self.config.streakBinFactor,
                                                                    axis=0).repeat(self.config.streakBinFactor,