[ImageDM] Mapping

[Peter Teuben]

On 11/21/2013 10:23 AM, Tim Jenness wrote:
> On Nov 20, 2013, at 15:38 , CresitelloDittmar, Mark <mdittmar at cfa.harvard.edu> wrote:
>
>>
>> 3) Can you give an example of the content for "Mapping.AxisMap"?
>>     Say I have an image with WCS ("RA", "DEC", "Time"), pixel axes (#1, #2, #3) plus value
>>     The 'Linear' portion is applied (CD matrix) to (#1, #2, #3) producing intermediate axes.
>>     a) do these have names?
>>
>>     AxisMap (pg 29) "is used to map the axes of the intermediate world coordinates (i.e., after the CD or PC transform, which may transpose or rotate the image axes) to the axes of
>> the final world coordinate system.
>>
> Do I get the impression that the VO WCS model is entirely based on the FITS WCS model? Has there been any thought to having a more flexible model that can, for example, support chained mappings (as implemented in the AST library and internally by HST)? Can the model support an IFU? Or a radio-style “channel map”?
>
> — 
> Tim Jenness
>

Related to Mark's comment on allowing having multiple instances of
Mapping, I can imagine the use case in the spectral domain, where a data
cube (channel maps) get a different doppler velocity depending on what
reference line you pick. A very common thing in modern day ALMA and JVLA
datasets.

peter