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NRAO Home > CASA > CASA Task Reference Manual |
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0.1.6 boxit
Requires:
Synopsis
Box regions in image above given threshold value.
Description
Returns a list of boxes, one for each contiguous set of pixels above the
threshold value. If given ”regionfile”, outputs boxes in regionfile+’.rgn’
Arguments
Inputs |
| ||
imagename |
| Name of image to threshold
| |
| allowed: | string |
|
| Default: |
| |
regionfile |
| Output region file
| |
| allowed: | string |
|
| Default: |
| |
threshold | mJy | Threshold value. Must include units.
| |
| allowed: | doublemJy |
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| Default: | 0.0 |
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maskname |
| Output mask name (optional).
| |
| allowed: | string |
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| Default: |
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chanrange |
| Range of channel ids
| |
| allowed: | string |
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| Default: |
|
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polrange |
| Range of polarization ids
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| allowed: | string |
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| Default: |
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minsize |
| Minimum number of pixels for a boxable island
| |
| allowed: | int |
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| Default: | 2 |
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diag |
| Count diagonal connections?
| |
| allowed: | bool |
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| Default: | False |
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boxstretch |
| Increase box sizes by this many pixels beyond
thresholded pixels.
| |
| allowed: | int |
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| Default: | 1 |
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overwrite |
| Overwrite existing region file?
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| allowed: | bool |
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| Default: | False |
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void
Example
This tool finds all 2-dimensional (RA/dec) regions in the given
4D (only!) image which are contiguous sets of pixels (islands) above the given ]
threshold. It creates a box for each island, a rectangular "cutout".
The boxes are stored as regions in the output regionfile. Works on
multi-plane images, but only boxes 2-D regions in each plane.
(Doesn’t create cubes/3D boxes.)
NOTE: THIS TASK WILL NOT WORK ON IMAGES THAT DO NOT HAVE 4 DIMENSIONS WHICH INCLUDE
A DIRECTION COORDINATE, A SPECTRAL COORDINATE, AND A STOKES COORDINATE. If your image
has, eg just a direction coordinate, you can add the required axes using ia.adddegaxes()
and remove them post-run with imsubimage with dropdeg=T.
imagename -- Name of input images:
default: none; example: imagename=’myimage.image’
regionfile -- Name of output region file (adds extension .rgn).
default: none; if not given uses imagename+’.rgn’
threshold -- value (with units) to use for island threshold.
default: 0.0.
maskname -- Optional output mask name.
default: ’’ (do not write mask image)
chanrange -- Range of channel ids
default: ’’ (find boxes for all channels)
example: ’5~7’ (find boxes for channel 5,6,7
polrange -- Range of polarization ids
default: ’’ (find boxes for all polarizations)
example: ’0~1’ (find boxes for polarization 0,1
minsize -- minimum size of island to get a box (in number of pixels)
default: 2
diag -- count diagonal connections as same island or not
default: False
boxstretch -- number of pixels to increase outward size of each box; can
range from -1 to 5.
default: 1
overwrite -- Overwrite existing region file and/or mask?
default: False. If False, gives warning if file exists.
More information about CASA may be found at the
CASA web page
Copyright © 2016 Associated Universities Inc., Washington, D.C.
This code is available under the terms of the GNU General Public Lincense
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