On 18 December 2011 09:13, Malcolm J. Currie <[log in to unmask]> wrote:
>>> Is there any way to define a custom region (say, with an ARD file) and
>>> get
>>> statistics over this region? In KAPPA the commands stats, mstats and
>>> histat
>>> produce statistics from NDFs but it seems to me that they work either
>>> over
>>> rectangular regions or over the full NDF.
>>>
>>
>> Use ARDMASK or REGIONMASK (supports STC regions) from KAPPA and then
>> STATS.
>
>
> A downside to the ARDMASK/REGIONMASK then STATS is that it won't show you
> the number of bad pixels in your region, since it will include
> bad pixels in the masked region too.
This would be true of a any scheme that is implemented within the NDF
library, such as appending an ard/stc-s description to the end of the
NDF name. The NDF library (i.e. ndfMap) can only return rectangular
sections to the calling app. It could set all pixels outside the
region bad, but there would be no way for the app to know which bad
pixels are inside or outside the region. A different "bad" value
could be used for pixels outside the region, but then all apps would
need to be changed to recognise this new "bad" value.
David
David
>
>> I think GAIA has a standalone application that does this in one
>> step but it's not available outside of GAIA (Which I think is a bit
>> annoying).
>
>
> Yes Image Analysis -> Image regions. However, my understanding is that is
> limited to pixel co-ordinates.
>
> As for KAPPA:STATS yes we could add an ARD region restriction, but then
> where do you draw the line adding this feature for other applications?
>
> Many years ago I advanced the idea of being able to specify ARD regions
> after the NDF name. There is the question of syntax and would you permit
> verbatim descriptions or merely indirection to a text file.
> Would you want an ARD dependency in NDF?
>
> Malcolm
>
>
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