Agenda Changes: ImageDM discussion during Education I
Rots, Arnold
arots at cfa.harvard.edu
Tue Jun 4 06:48:46 PDT 2013
I suppose I was - but I heard or saw no announcement of when and where this
was
going to happen and no one told me. There was a glaring lack of
communication.
- Arnold
On Tue, Jun 4, 2013 at 5:15 AM, François Bonnarel <
francois.bonnarel at astro.unistra.fr> wrote:
> Hi Arnold,Hi everybody,
> Le 17/05/2013 09:46, Rots, Arnold a écrit :
>
> I presented these two alternatives for an open discussion. But you were in
> another room !!!
>
> Best regards
> François
>
>
-------------------------------------------------------------------------------------------------------------
Arnold H. Rots Chandra X-ray
Science Center
Smithsonian Astrophysical Observatory tel: +1 617 496
7701
60 Garden Street, MS 67 fax: +1 617
495 7356
Cambridge, MA 02138
arots at cfa.harvard.edu
USA
http://hea-www.harvard.edu/~arots/
--------------------------------------------------------------------------------------------------------------
On Tue, Jun 4, 2013 at 5:15 AM, François Bonnarel <
francois.bonnarel at astro.unistra.fr> wrote:
> Hi Arnold,Hi everybody,
> Le 17/05/2013 09:46, Rots, Arnold a écrit :
>
> Since that session was not really completed (or, if it did,
> I wasn't able to find out where and when), I posted some
> comments on the DM sessions Twiki page, in the form of
> some slides regarding the implementation of WCS in STC.
> You may recall that Francois asserted that there was no
> such support.
>
> This is not true. I said it could be difficult or heavy in the first DAL
> session. But I didn't say there was no support. In the small Image DM
> session I presented slides (there are on the DM Heidelberg session page)
> where I proposed STC utypes for the ref pos and the CDmatrix and
> projection. I identified Cart2DRefFrame as the package to do that. And I
> also identified PixelCoordSystem as the package able to describe the
> Reference pixel (CRPIX). I didn't notice your slides at that moment,
> sorry. Below I discuss your example in term of ImageDM utypes (path
> utypes) to be used in DAL services query responses.
>
> There is; see: table 4, Appendix A, and the
> example in Appendix B.2.
> The main issue is that STC data model was designed to provide a
> characterization of the data it referred to along its coordinates.
> Part of that was the WCS projection.
> When the characterization role is rejected and one starts
> cherry-picking pieces from the data model, it becomes more
> difficult to put the WCS information back in, since the integrity
> of the data model has been lost.
> To be blunt: the WCS support is there, but the way you choose
> to use STC may make it very difficult to take advantage of it.
>
> If we think to provide WCS (or Mapping) for an image along the lines of
> the example in your slides what would be the utypes ?
> I found those with their equivalent WCS FITS Keywords
> PixelCoordSystem.PixelCoordFrame.Cart2DrefFrame.projection ---> second
> part of CTYPE
> PixelCoordSystem.PixelCoordFrame.Cart2DrefFrame.Transform2 ----> "CDELT"
> keywords
> PixelCoordSystem.PixelCoordFrame.CoordRefPos.Vector2DCoordinate ---->
> "CRVAL" Keywords
> PixelCoordSystem.PixelCoordFrame.CARTESIAN.naxes ----> NAXES
> PixelCoordSystem.PixelCoordFrame.ReferencePixel.Pixel2D.Name1 ----> First
> part of CTYPE1
> PixelCoordSystem.PixelCoordFrame.ReferencePixel.Pixel2D.Name2 -----> First
> part of CTYPE2
> PixelCoordSystem.PixelCoordFrame.ReferencePixel.Pixel2D.Value2 ------>
> CRPIX Keywords
>
> Of course this works. The STC/WCS solution I had in mind was a little
> different because WCS is actually at least a two step transformation
> Sphere ------> projected plane (Wolrld coordinates to "standard"
> coordinates)
> projected plane ----> pixel plane
> I thought the first transformation is best rendered SEMANTICALLY by a real
> AstroCoordSystem with a Custom Cart2DSpaceRefFrame and a Custom RefPos.
> These features do not really belong to Pixel space in my sense.
> Then the second transformation (using the matrix/CDELT Transform2 and
> Pixel reference position) could be rendered by the PixelCoordinateSystem
>
> Alternatively I also proposed the Mapping stuff as it is done in the
> ImageDM draft. Something much closer the organisation of WCS keywords like
>
> Mapping.CoordRefPixel
> Mapping.CDmatrix
> Mapping.Projection
> etc...
>
>
> I presented these two alternatives for an open discussion. But you were in
> another room !!!
>
> Best regards
> François
>
>
> Cheers,
>
> - Arnold
>
>
> On Mon, May 13, 2013 at 1:24 PM, Jesus Salgado <jsalgado at sciops.esa.int>wrote:
>
>> Dear all,
>>
>> Massimo Ramella has kindly provided part of the time of his Education 1
>> session on
>> Thursday 11:00–12:30 to finish the discussion on ImageDM draft that we
>> were having
>> during DM1 session.
>>
>> That means, we will have F. Bonnarel presentation that could not give
>> today plus
>> the brainstorming.
>>
>> Please take note of that :)
>> Cheers,
>> Jesus
>>
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>
>
> --
>
> -------------------------------------------------------------------------------------------------------------
> Arnold H. Rots Chandra X-ray
> Science Center
> Smithsonian Astrophysical Observatory tel: +1 617 496
> 7701
> 60 Garden Street, MS 67 fax: +1 617
> 495 7356
> Cambridge, MA 02138
> arots at cfa.harvard.edu
> USA
> http://hea-www.harvard.edu/~arots/
>
> --------------------------------------------------------------------------------------------------------------
>
>
>
>
--
-------------------------------------------------------------------------------------------------------------
Arnold H. Rots Chandra X-ray
Science Center
Smithsonian Astrophysical Observatory tel: +1 617 496
7701
60 Garden Street, MS 67 fax: +1 617
495 7356
Cambridge, MA 02138
arots at cfa.harvard.edu
USA
http://hea-www.harvard.edu/~arots/
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