[iaufwg] [fitsbits] IAU FWG approval of the new FITS Standard

[Steve Allen]

On Tue 2008-05-27T13:25:12 -0400, William Pence hath writ:

> Rather than store world coordinates separately for each datum (e.g. as
> is done for random groups data), the regular lattice structure of a
> FITS image offers the possibility of defining rules for computing
> world coordinates at each point.

> CRPIXj - [floating-point, indexed, default: 0.0]
>   Location of the reference point in the image for axis j, in units
>   of pixels, corresponding to $r_j$ in Eq. (8.1).  Note that the
>   reference point may lie outside the image and that the first pixel
>   in the image has pixel coordinates $(1.0, 1.0, \ldots)$.

I am not comfortable with the phrases "regular lattice structure" or
"units of pixels".  The data array is metric free, and I think it is
misleading to use any language that indicates it is "regular" or has
"units".  In the absence of WCS even the concept of adjacency in the
array does not necessarily have meaning.

--
Steve Allen                 <sla at ucolick.org>                WGS-84 (GPS)
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