lsst.meas.base.transforms Namespace Reference

Classes
class	MeasurementTransform
class	NullTransform
class	PassThroughTransform
class	SimpleCentroidTransform

Detailed Description

Measurement transformations.

When a measurement plugin is run, it provides raw, uncalibrated outputs such
as pixel positions. A transformation may be run as a post-processing step to
convert those outputs to calibrated quantities, such as celestial coordinates.

At construction, the transformation is passed the configuration and name of
the plugin whose outputs it will be transforming (all fields in the input
table produced by that plugin will have their field names prefixed by the
plugin name) and a `~lsst.afw.table.SchemaMapper` which holds the schemata for
the input and output catalogs and which may be used to directly map fields
between the catalogs.

When a transformer is called, it is handed a `~lsst.afw.table.SourceCatalog`
containing the measurements to be transformed, a `~lsst.afw.table.BaseCatalog`
in which to store results, and information about the WCS and calibration of
the data. It may be safely assumed that both are contiguous in memory, thus a
``ColumnView`` may be used for efficient processing. If the transformation is
not possible, it should be aborted by throwing an exception; if this happens,
the caller should assume that the contents of the output catalog are
inconsistent.

Transformations can be defined in Python or in C++. Python code should inherit
from `MeasurementTransform`, following its interface.