QuickFrameMeasurementTask¶
- class lsst.pipe.tasks.quickFrameMeasurement.QuickFrameMeasurementTask(config, *, display=None, **kwargs)¶
Bases:
Task
WARNING: An experimental new task with changable API! Do not rely on yet!
This task finds the centroid of the brightest source in a given CCD-image and returns its centroid and a rough estimate of the seeing/PSF.
It is designed for speed, such that it can be used in observing scripts to provide pointing offsets, allowing subsequent pointings to place a source at an exact pixel position.
The approach taken here is deliberately sub-optimal in the detection and measurement sense, with all optimisation being done for speed and robustness of the result.
A small set of unit tests exist for this task, which run automatically if afwdata is setup. These, however, are stricky unit tests, and will not catch algorithmic regressions. TODO: DM-29038 exists to merge a regression real test which runs against 1,000 LATISS images, but is therefore slow and requires access to the data.
- Parameters:
- config
lsst.pipe.tasks.quickFrameMeasurement.QuickFrameMeasurementTaskConfig
Configuration class for the QuickFrameMeasurementTask.
- display
lsst.afw.display.Display
, optional The display to use for showing the images, detections and centroids.
- config
- Returns:
- result
lsst.pipe.base.Struct
Return strucure containing whether the task was successful, the main source’s centroid, its the aperture fluxes, the ixx and iyy of the source, and the median ixx, iyy of the detections in the exposure. See run() method for further details.
- result
- Raises:
- This task should never raise, as the run() method is enclosed in an
- except Exception block, so that it will never fail during observing.
- Failure modes should be limited to returning a return Struct() with the same
- structure as the success case, with all value set to np.nan but with
- result.success=False.
Methods Summary
checkResult
(exp, centroid, srcNum, percentile)Perform a final check that centroid location is actually bright.
detectObjectsInExp
(exp, nSigma, nPixMin[, grow])Run a very basic but fast threshold-based object detection on an exposure Return the footPrintSet for the objects in a postISR exposure.
Empty (clear) the metadata for this Task and all sub-Tasks.
Get metadata for all tasks.
Get the task name as a hierarchical name including parent task names.
getName
()Get the name of the task.
Get a dictionary of all tasks as a shallow copy.
makeField
(doc)Make a
lsst.pex.config.ConfigurableField
for this task.makeSubtask
(name, **keyArgs)Create a subtask as a new instance as the
name
attribute of this task.run
(exp, *[, donutDiameter, doDisplay])Calculate position, flux and shape of the brightest star in an image.
timer
(name[, logLevel])Context manager to log performance data for an arbitrary block of code.
Methods Documentation
- static checkResult(exp, centroid, srcNum, percentile)¶
Perform a final check that centroid location is actually bright.
- Parameters:
- exp
lsst.afw.image.Exposure
The exposure on which to operate
- centroid
tuple
offloat
Location of the centroid in pixel coordinates
- scrNum
int
Number of the source in the source catalog. Only used if the check is failed, for debug purposes.
- percentile
float
Image’s percentile above which the pixel containing the centroid must be in order to pass the check.
- exp
- Raises:
- ValueError
Raised if the centroid’s pixel is not above the percentile threshold
- static detectObjectsInExp(exp, nSigma, nPixMin, grow=0)¶
Run a very basic but fast threshold-based object detection on an exposure Return the footPrintSet for the objects in a postISR exposure.
- Parameters:
- Returns:
- footPrintSet
lsst.afw.detection.FootprintSet
FootprintSet containing the detections.
- footPrintSet
- getFullMetadata() TaskMetadata ¶
Get metadata for all tasks.
- Returns:
- metadata
TaskMetadata
The keys are the full task name. Values are metadata for the top-level task and all subtasks, sub-subtasks, etc.
- metadata
Notes
The returned metadata includes timing information (if
@timer.timeMethod
is used) and any metadata set by the task. The name of each item consists of the full task name with.
replaced by:
, followed by.
and the name of the item, e.g.:topLevelTaskName:subtaskName:subsubtaskName.itemName
using
:
in the full task name disambiguates the rare situation that a task has a subtask and a metadata item with the same name.
- getFullName() str ¶
Get the task name as a hierarchical name including parent task names.
- Returns:
- fullName
str
The full name consists of the name of the parent task and each subtask separated by periods. For example:
The full name of top-level task “top” is simply “top”.
The full name of subtask “sub” of top-level task “top” is “top.sub”.
The full name of subtask “sub2” of subtask “sub” of top-level task “top” is “top.sub.sub2”.
- fullName
- getName() str ¶
Get the name of the task.
- Returns:
- taskName
str
Name of the task.
- taskName
See also
getFullName
Get the full name of the task.
- getTaskDict() dict[str, weakref.ReferenceType[lsst.pipe.base.task.Task]] ¶
Get a dictionary of all tasks as a shallow copy.
- Returns:
- taskDict
dict
Dictionary containing full task name: task object for the top-level task and all subtasks, sub-subtasks, etc.
- taskDict
- classmethod makeField(doc: str) ConfigurableField ¶
Make a
lsst.pex.config.ConfigurableField
for this task.- Parameters:
- doc
str
Help text for the field.
- doc
- Returns:
- configurableField
lsst.pex.config.ConfigurableField
A
ConfigurableField
for this task.
- configurableField
Examples
Provides a convenient way to specify this task is a subtask of another task.
Here is an example of use:
class OtherTaskConfig(lsst.pex.config.Config): aSubtask = ATaskClass.makeField("brief description of task")
- makeSubtask(name: str, **keyArgs: Any) None ¶
Create a subtask as a new instance as the
name
attribute of this task.- Parameters:
- name
str
Brief name of the subtask.
- **keyArgs
Extra keyword arguments used to construct the task. The following arguments are automatically provided and cannot be overridden:
config
.parentTask
.
- name
Notes
The subtask must be defined by
Task.config.name
, an instance ofConfigurableField
orRegistryField
.
- run(exp, *, donutDiameter=None, doDisplay=False)¶
Calculate position, flux and shape of the brightest star in an image.
Given an an assembled (and at least minimally ISRed exposure), quickly and robustly calculate the centroid of the brightest star in the image.
- Parameters:
- exp
lsst.afw.image.Exposure
The exposure in which to find and measure the brightest star.
- donutDiameter
int
orfloat
, optional The expected diameter of donuts in pixels for use in the centre of mass centroid measurement. If None is provided, the config option is used.
- doDisplay
bool
Display the image and found sources. A diplay object must have been passed to the task constructor.
- exp
- Returns:
- result
lsst.pipe.base.Struct
- Struct containing:
Whether the task ran successfully and found the object (bool) The object’s centroid (float, float) The object’s ixx, iyy (float, float) The object’s 70 pixel aperture flux (float) The object’s 25 pixel aperture flux (float) The images’s median ixx, iyy (float, float)
If unsuccessful, the success field is False and all other results are np.nan of the expected shape.
- result
Notes
Because of this task’s involvement in observing scripts, the run method should never raise. Failure modes are noted by returning a Struct with the same structure as the success case, with all value set to np.nan and result.success=False.