[ImageDM] Mapping

[CresitelloDittmar, Mark]

Doug,

What I believe the document shows is that
  - the FITS WCS Serialization ( as encapsulated by the Mapping object ) is
compatible with the STC Model.

Given that FITS-WCS serialization is a widely used standard, it is
important to illustrate that the STC model is compatible with it.
I would expect that to have happened before it became a recommendation.  It
may be useful to have a reference document showing the various FITS-WCS
serialization options and their representations in STC objects.  A lot of
that information is in the document I just put out, but is not directly
shown.

But I don't understand the concern behind the questions below.

It reads like you are asking how many tools/libraries understand the
STC-S/STC-X serializations before considering use of the Model within
ImageDM.
I don't see the relevance.  All we should need to show is that it is
compatible with whatever existing standard serializations are required
(FITS-WCS is all I've heard).
Is there another Ascii/XML representation of WCS that existing tools do
understand?

If the concern is that STC may allow additional options not representable
by FITS-WCS, I don't think that is a constraint.

I feel like we've been around this barn before, so maybe someone else can
help illustrate the issue from another angle to help clarify things for me?

Mark



On Tue, Dec 10, 2013 at 12:34 PM, Douglas Tody <dtody at nrao.edu> wrote:

> Hi Mark -
>
> The document at the link below does not load, at least for me.  I also
> went into Volute and poked around, but could not bring it up, so I was
> not able to review the comparision of capabilties.
>
> This looks like the most in-depth analysis yet of WCS vs STC, which is
> good.  It will be good to have such a comparison to inform thoughts
> about future applications or directions, in particular what capabilities
> are missing or added by each WCS formalism.  In the meantime it would be
> good to know the following:
>
>     o   What libraries are currently available that implement STC-WCS,
>         and in what languages?  (I know that there is something at least
>         STC-related in Starlink AST, for example, but do not know how
>         complete it is).  Do these libraries support capabilities such
>         as forward and inverse transforms for supported WCS functions?
>
>     o   Has the mapping (no pun intended) from FITS WCS to STC WCS and
>         vice versa been worked out and implemented in any libraries?  So
>         for example if we have data with a FITS WCS, can this be easily
>         converted to STC?  How complete is the mapping?  Such easy to
>         use load/save WCS tools would be necessary to enable use the STC
>         formalism with data or applications currently implementing FITS
>         WCS.
>
>     o   Do we know of any current science applications or tools that
>         implement STC for its WCS capabilities?  To what extent is this
>         supported in CIAO or DS9 for example, or other software?
>
>     o   What is the extent of STC WCS support in current archive data
>         collections?  We know that FITS WCS is very widely implemented
>         in current archives (hence supporting it is mandatory), but if
>         STC is becoming more broadly used to describe WCS in archive
>         data, this would increase the priority for supporting it.
>
> Regardless of the technical merits of these two technologies, we need to
> know the answers to the above questions before deciding to favor, or
> possibly even support, STC-WCS for image access and analysis, at least
> in the short term for cube project development over the next 6-12
> months.
>
>         - Doug
>
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