Peter,
> > You can use AST_SIMPLIFY on FrameSets as well as Mappings (since FrameSet
> > inherits from Mapping). The FrameSet implementation of AST_SIMPLIFY
> > simplifies all the Mappings in the FrameSet.
>
> And returns you a single mapping from base to current, I thought... Are
> you saying that I can simplify a FrameSet and what I get back is a
> FrameSet with the intra-frame mappings simplified (and all Frames still in
> place etc.)? That's what I want. If that's the case I didn't know that and
> I could get the effect I need after stage 1 below I guess.
If you use AST_SIMPLIFY on a FrameSet, it returns a copy of the FrameSet
in which all the Mappings have been simplified. I've just looked in the
docs and indeed this is not mentioned - I'll update the docs.
> > > Anyway by the time I see this it's too late for the efficiency gains
> > > to useful (having passed an array of 8192 double precision values into
> > > strings once already).
> >
> > Can you spell out the chain of format conversions which GAIA performs?
>
> -> Get FrameSet from NDF_GTWCS
Yep - stick a call to AST_SIMPLIFY in here.
>
> -> Convert FrameSet into FITS headers (slow for large LutMaps)
>
> -> Passed through Skycat into GAIA
>
> -> Read FITS headers to recover FrameSet (slow for large LutMaps)
David
|