1.104. mkGrid

Full Name: herschel.hifi.dp.otf.MkGridTask
Alias: mkGrid
Type: Java Task - Java Task
Import: from herschel.hifi.dp.otf import MkGridTask
Category

HIFI/Analysis

Description

produces a GridMap from a HifiTimelineProduct.

This task makes the GridMap that defines the regular grid to make a cube for a HifiTimelineProduct.

The images would be produced by performing two dimensional gridding of a number of spectra irregularly distributed over some area of the sky observed in a mapping mode. The spectra are read from a number of HifiSpectrumDatasets within the HifiTimelineProduct.

This task computes a regular grid that covers the region of the sky where the spectra have been observed.

API details

Properties

HifiTimelineProduct htp [INPUT, MANDATORY, default=no default value]

container of the spectra for which a regular grid has to be computed

Double beam [INPUT, OPTIONAL, default=no default value]

No default value.

Provides the antenna beam width (HPBW), in seconds of arc.

Int2d channels [INPUT, OPTIONAL, default=empty by default]

by default, in this case all channels are selected for each segment (subband)

This parameter can be used to "crop" a part of spectral range.

For each segment, this Int2d has a row with two elements, the first element the start channel, and the second element specifies the last channel, i.e. the start and the end of the range of channels to be read per subband

Int1d mapSize [INPUT, OPTIONAL, default=Int1d(2,0) i.e. autocompute optimal]

this parameter may be used to specify the size of the map to be generated; the size is given along the x and y axes, in pixels.

When both sizes are equal, a Double1d with a single element can be provided.

Otherwise, this parameter array must contain two elements:

  • width of the map, size along the x axis

  • height of the map, size along the y axis

By default, this parameter is set to zero, in order to let algorithm choose the optimal map dimensions.

Double1d refPixel [INPUT, OPTIONAL, default=Double1d(2, 0.), i.e. autocompute]

specifies which is the reference pixel (in both axes). The coordinates of this reference pixel can also be specified by means of another optional parameter, refPixelCoordinates.

By default, this parameter is set to NaN, to let the algorithm choose an appropriate reference pixel.

If both x- and y-axis values of the reference pixel are equal, a Double1d array with a single element can be provided.

Otherwise, this parameter must have two elements:

  • first element of the Double1d array specifies the value of the reference pixel in the x axis,

  • second element of the Double1d array specifies the value of the reference pixel in the y axis

This reference pixel is referred to the bottom most, left most pixel of the regular grid that covers the whole area to be mapped. That is, the (0,0) pixel corresponds to the center of bottom-most, left-most pixel of the regular grid computed for the map.

Double1d refPixelCoordinates [INPUT, OPTIONAL, default=Double1d(2, 0.), i.e. autocompute]

specifies the coordinates of the reference point, in the x and y axes, in the same units of the input data (for HifiSpectrumDataset, usually degrees).

By default, this parameter is set to zero to let algorithm compute the offset that corresponds to the reference pixel.

Otherwise, this parameter must have two elements:

  • first element: coordinate of the reference pixel in the x axis,

  • second element: coordinate of the reference pixel in the y axis

Double1d pixelSize [INPUT, OPTIONAL, default=Double1d(2, 0.), i.e. autocompute]

defines the size of the pixels in the x and y axes, measured in arc seconds per pixel.

By default this parameter is set to zero to let algorithm compute the optimal size.

If both x- and y-axis values are equal, a Double1d array with a single parameter can be chosen.

Otherwise, this parameter must have two elements:

  • size along the x-axis in the first element,

  • size along the y-axis in the second one.

Double1d smoothFactor [INPUT, OPTIONAL, default=Double1d(2, 1.0), i.e. autocompute]

provides a smooth factor, increasing (broadening) the area of influence (kernel size) used to compute each pixel.

String1d datasetTypes [INPUT, OPTIONAL, default=String1d(["science"])]

name of the types of HifiSpectrumDatasets that contain the spectra observed by the instrument when aimed to the source.

The spectra used for the gridding are only those from the HifiSpectrumDataset's whose type is equal to the given dataset type and flagged as 'isLine' datasets.

String datasetType [INPUT, OPTIONAL, default="science"]

name of the type of HifiSpectrumDatasets that contain the spectra observed by the instrument when aimed to the source.

The spectra used for the gridding are only those from the HifiSpectrumDataset's whose type is equal to the given dataset type and flagged as 'isLine' datasets.

Int1d datasetIndices [INPUT, OPTIONAL, default=no default value]

indices of the HifiSpectrumDatasets to be used to retrieve spectra to perform the gridding into a cube.

This parameter can be used to grab any datasets within the HifiTimelineProduct.

If this is parameter is given the datasetType parameter will be ignored.

Boolean ignoreOffs [INPUT, OPTIONAL, default=true.]

tells whether ignore datasets whose type matches the given datasetType(s) but which are not took from the source (isLine column of the HTP' summary table is false in those datasets) or, on the contrary, grab also them.

TableDataset offsetsTable [INPUT, OPTIONAL, default=no default value]

auxiliary table which can be used to provide spectra coordinates.

this input is an alternative way to provide the spectra positions when neither the auxiliary products are available nor the latitude and longitude columns are already computed in the HifiSpectrumDatasets.

See also

History

  • 2010-06-28 - ESS: First version. Based on DoGriddingTask.