Post by Robin on Aug 9, 2017 15:37:38 GMT 8
Hi all,
I thought I might show a particularly nice case of where using a profound segmentation with a further dilation on top can be quite powerful. This banks on the idea that if you are able to accurately identify the sources outside of the main target, then one can expand the segmentation of the main target quite freely and without contributions from those external sources.
I use the following function calls to create the segmentation map:
Which produces the following segmentations:
(Left) ProFound only. (Right) with extra dilation step.
The extra step of dilation allows for a segmentation that encompasses many more sky pixels and hence provides a better, let's say, "anchor point" for fitting a profile. The same could also be achieved with a similar call to profitSegImExpand( ).
*Note* that some of these function names are likely to be changing in upcoming versions of ProFit/ProFound
** EDIT **
Further to Soheil's post below, here is what the default setting look like for this particular galaxy:
Which unfortunately does not capture the diffuse wings of the galaxy. In most cases, the defaults work pretty well but it's worth doing some extra dilation for these types of galaxies.
I thought I might show a particularly nice case of where using a profound segmentation with a further dilation on top can be quite powerful. This banks on the idea that if you are able to accurately identify the sources outside of the main target, then one can expand the segmentation of the main target quite freely and without contributions from those external sources.
I use the following function calls to create the segmentation map:
segmentation = profitProFound(image, sigma=2.75, skycut=1.0, tolerance=4, size=21,
magzero=ZERO_POINT, gain=GAIN, header=header,
stats=TRUE, rotstats=TRUE, boundstats=TRUE, plot=TRUE)
# Find the main (central) source
mainID = find_main(segmentation$segstats,dims) # a function to find the centre-most source
segmentation = profitMakeSegimDilate(image, segmentation$segim, plot=TRUE, size= 85,expand=mainID)
Which produces the following segmentations:
(Left) ProFound only. (Right) with extra dilation step.
The extra step of dilation allows for a segmentation that encompasses many more sky pixels and hence provides a better, let's say, "anchor point" for fitting a profile. The same could also be achieved with a similar call to profitSegImExpand( ).
*Note* that some of these function names are likely to be changing in upcoming versions of ProFit/ProFound
** EDIT **
Further to Soheil's post below, here is what the default setting look like for this particular galaxy:
Which unfortunately does not capture the diffuse wings of the galaxy. In most cases, the defaults work pretty well but it's worth doing some extra dilation for these types of galaxies.
