SingleFrameNaiveTrailPlugin¶

class lsst.meas.extensions.trailedSources.SingleFrameNaiveTrailPlugin(config, name, schema, metadata)¶

Bases: lsst.meas.base.SingleFramePlugin

Naive trailed source measurement plugin

Measures the length, angle from +x-axis, and end points of an extended source using the second moments.

Parameters:	config: `SingleFrameNaiveTrailConfig` Plugin configuration. name: `str` Plugin name. schema: `lsst.afw.table.Schema` Schema for the output catalog. metadata: `lsst.daf.base.PropertySet` Metadata to be attached to output catalog.

See also

lsst.meas.base.SingleFramePlugin

Notes

This measurement plugin aims to utilize the already measured adaptive second moments to naively estimate the length and angle, and thus end-points, of a fast-moving, trailed source. The length is solved for via finding the root of the difference between the numerical (stack computed) and the analytic adaptive second moments. The angle, theta, from the x-axis is also computed via adaptive moments: theta = arctan(2*Ixy/(Ixx - Iyy))/2. The end points of the trail are then given by (xc +/- (length/2)*cos(theta) and yc +/- (length/2)*sin(theta)), with xc and yc being the centroid coordinates.

Attributes Summary

`APCORR_ORDER`
`CENTROID_ORDER`
`DEFAULT_CATALOGCALCULATION`
`FLUX_ORDER`
`SHAPE_ORDER`
`registry`

Methods Summary

`computeLength`(Ixx, Iyy)	Compute the length of a trail, given unweighted second-moments.
`computeRaDec`(exposure, x, y)	Convert pixel coordinates to RA and Dec.
`fail`(measRecord[, error])	Record failure
`findLength`(Ixx, Iyy)	Find the length of a trail, given adaptive second-moments.
`getExecutionOrder`()	Get the relative execution order of this plugin.
`getLogName`()
`getTransformClass`()	Get the measurement transformation appropriate to this plugin.
`measure`(measRecord, exposure)	Run the Naive trailed source measurement algorithm.
`measureN`(measCat, exposure)	Measure the properties of blended sources on a single image.

Attributes Documentation

APCORR_ORDER = 3.0¶

CENTROID_ORDER = 0.0¶

DEFAULT_CATALOGCALCULATION = 4.0¶

FLUX_ORDER = 2.0¶

SHAPE_ORDER = 1.0¶

registry = <lsst.meas.base.pluginRegistry.PluginRegistry object>¶

Methods Documentation

static computeLength(Ixx, Iyy)¶: Compute the length of a trail, given unweighted second-moments.

static computeRaDec(exposure, x, y)¶

Convert pixel coordinates to RA and Dec.

Parameters:	exposure : `lsst.afw.image.ExposureF` Exposure object containing the WCS. x : `float` x coordinate of the trail centroid y : `float` y coodinate of the trail centroid
Returns:	ra : `float` Right ascension. dec : `float` Declination.

fail(measRecord, error=None)¶

Record failure

See also

lsst.meas.base.SingleFramePlugin.fail

classmethod findLength(Ixx, Iyy)¶

Find the length of a trail, given adaptive second-moments.

Uses a root finder to compute the length of a trail corresponding to the adaptive second-moments computed by previous measurements (ie. SdssShape).

Parameters:	Ixx : `float` Adaptive second-moment along x-axis. Iyy : `float` Adaptive second-moment along y-axis.
Returns:	length : `float` Length of the trail. results : `scipy.optimize.RootResults` Contains messages about convergence from the root finder.

classmethod getExecutionOrder()¶

Get the relative execution order of this plugin.

Must be reimplemented as a class method by concrete derived classes.

getLogName()¶

static getTransformClass()¶

Get the measurement transformation appropriate to this plugin.

This returns a subclass of transforms.MeasurementTransform, which may be instantiated with details of the algorithm configuration and then called with information about calibration and WCS to convert from raw measurement quantities to calibrated units. Calibrated data is then provided in a separate output table.

Notes

By default, we copy everything from the input to the output without transformation.

measure(measRecord, exposure)¶

Run the Naive trailed source measurement algorithm.

Parameters:	measRecord : `lsst.afw.table.SourceRecord` Record describing the object being measured. exposure : `lsst.afw.image.Exposure` Pixel data to be measured.

Navigation

SingleFrameNaiveTrailPlugin¶