hermes.pipeline.components.modelbackground.modelBackground Class Reference

Compute a model for the background over the whole frame. More...

Inheritance diagram for hermes.pipeline.components.modelbackground.modelBackground:

Public Member Functions
def	__init__
	Make a Hermes component and initialize variables.
def	optionsAreValid
	Check user options, or use default values. More...
def	__call__
	Run begins here.
def	averageFilter
	average filter could be improved for speed
def	averageFilterLarger
	average filter
Public Member Functions inherited from hermes.pipeline.core.pipelinecomponent.PipelineComponent
def	__init__
def	__call__
def	optionsAreValid
def	getOptions
def	setOptions
def	checkExistShapeUnits
def	isOption

Public Attributes
	gOrder
	Set gOrder to the user given value, or use default 8.
	longOrder
	Set longOrder to the user given value, or use default 30.
	halfLengthFilterCrossOrder
	Set halfLengthFilterCrossOrder to the user given value, or use default 2.
	halfLengthLocalBackgroundFeature
	Set halfLengthLocalBackgroundFeature to the user given value, or use default 250.
	isDebug
	Set isDebug to the user given value, or use default False.
	results
	rowMid
	set rowMid according relative coordinates or not
Public Attributes inherited from hermes.pipeline.core.pipelinecomponent.PipelineComponent
	options
	logger
	ConsoleLogSeverity
	default value
	canShowGraphics
	when machine does not run matplotlib. More...

Detailed Description

Compute a model for the background over the whole frame.

PURPOSE :

This module uses the estimated background intensities mid-between the
spectral orders to generate model intensities in all pixels. The model
is computed on a grid of 'relative background coordinates' (see the
module measureBackground) and then interpolated to the actual pixels.

The algorithm uses five-point Lagrangian interpolation in rows, using
'column-smoothed' input data, with an additonal local smoothing operation
before interpolation to the actual pixel coordinates. Its success depends
critically on the level of smoothness of the input data. The choice of the
algorithm should possibly be re-considered when commissioning data are
available.



COMMENTS :

The principle to use mid-between spectral order intensities as anchor
points for the background model assumes that SPECTRAL ORDERS DO NOT OVERLAP.
If untrue, then the background will be overestimated (especially in the
centre of the spectral orders and in deep absorption lines) and, as a
consequence, the apparent normalized cross-order profile in a spectral
order will be biased in a manner that is correlated with the shape of the
spectrum. A test on the spectral order overlap can be performed on the
extracted spectra, checking how precisely completely black telluric lines
have zero flux.



SYNTAX :



INPUT CONSTANTS FROM INSTRUMENT MODEL :




INPUT DATA FROM RESULTDICT :

midInterorderBackground
backgroundOrderPositions




OPTIONS READ FROM OPTIONDICT :

MANDATORY :

OPTIONAL :
    isDebug (Boolean : True or False)
        default value : False
        writes two fits files with the results :
            splinedModelAndResiduals    in 'T30splinedmr.fits')
            modelAndResiduals[1000,:]   in 'T31mr.fits')
    definition of range for filter used to identify local features in background
        halfLengthFilterAlongOrder, default = 30
        halfLengthFilterCrossOrder, default = 2
        halfLengthLocalBackgroundFeature, default = 250
    degree of polynomial for fit along a specific mid-interorder cut
        degreeBackPolAlongOrder, default = 8


# TO CHECK :



OUTPUT written in the self.results :

    "modelBackgroundImage"
    "modelAndResiduals"
    "modelBackgroundVarImage"
    "modelBackgroundCoefficients"

Member Function Documentation

def hermes.pipeline.components.modelbackground.modelBackground.optionsAreValid	(		self,
			optionDict
	)

Check user options, or use default values.

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The documentation for this class was generated from the following file:

• pipeline/components/modelbackground.py