DeblenderMetrics

class lsst.meas.extensions.scarlet.DeblenderMetrics(maxOverlap: array, fluxOverlap: array, fluxOverlapFraction: array, blendedness: array)

Bases: object

Metrics and measurements made on single sources.

Store deblender metrics to be added as attributes to a scarlet source before it is converted into a SourceRecord. TODO: When DM-34414 is finished this class will be eliminated and the metrics will be added to the schema using a pipeline task that calculates them from the stored deconvolved models.

All of the parameters are one dimensional numpy arrays, with an element for each band in the observed images.

maxOverlap is useful as a metric for determining how blended a source is because if it only overlaps with other sources at or below the noise level, it is likely to be a mostly isolated source in the deconvolved model frame.

fluxOverlapFraction is potentially more useful than the canonical “blendedness” (or purity) metric because it accounts for potential biases created during deblending by not weighting the overlapping flux with the flux of this sources model.

Attributes:

maxOverlap:

The maximum overlap that the source has with its neighbors in a single pixel.

fluxOverlap:

The total flux from neighbors overlapping with the current source.

fluxOverlapFraction:

The fraction of flux from neighbors/source flux for a given source within the source’s footprint.

blendedness:

The metric for determining how blended a source is using the Bosch et al. 2018 metric for “blendedness.” Note that some surveys use the term “purity,” which is 1-blendedness.