#1
|
|||
|
|||
[fitsbits] CDELTn
Section 2.1.2 of FITS-WCS paper 1 says "Furthermore, all CDELTi must
be non-zero." Even if NAXISn is 1, that one pixel should still have some width. If any CDELT is zero then the transformation from pixel to WCS cannot be inverted. David On 18/09/2007, Francois Ochsenbein wrote: Hello, I just found a curiosity: FITS files having CDELTn axis set to zero. This may look strange, but when the corresponding NAXISn is 1, this should be harmless. Is the value zero actually forbidden in the FITS definition ? (I did not find this restriction in the FITS definition). It seems that fv does not like such FITS file, it generates an error. --Francois ================================================== ============================== Francois Ochsenbein ------ Observatoire Astronomique de Strasbourg 11, rue de l'Universite F-67000 STRASBOURG Phone: +33-(0)390 24 24 29 Email: (France) Fax: +33-(0)390 24 24 17 ================================================== ============================== _______________________________________________ fitsbits mailing list http://listmgr.cv.nrao.edu/mailman/listinfo/fitsbits -- Note my change of e-mail address. Please send e-mail to from now on. |
#2
|
|||
|
|||
[fitsbits] CDELTn
On Tue, 18 Sep 2007, David Berry wrote:
Section 2.1.2 of FITS-WCS paper 1 says "Furthermore, all CDELTi must be non-zero." And the WCS paper is "incorporated by reference" in the draft FITS standard 3.0. So it looks like Francois has spotted something which is best to spell out clearly and explicitly also in the standard (and we in the technical panel have missed). .... oh, wait a moment ... if this wasn't stated before WCS came out, FITS file created before then would be exempt from the "new" requirement, wont't they ? How do these go together ? -- ---------------------------------------------------------------------- is a newsreading account used by more persons to avoid unwanted spam. Any mail returning to this address will be rejected. Users can disclose their e-mail address in the article if they wish so. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
[fitsbits] CDELTn | Phil Hodge | FITS | 0 | September 18th 07 01:44 PM |
[fitsbits] CDELTn | Francois Ochsenbein | FITS | 0 | September 18th 07 12:17 PM |
[fitsbits] fitsbits--sci.astro.fits gateway fully operationalagain | Don Wells | FITS | 0 | September 29th 06 05:17 PM |
[fitsbits] sci.astro.fits link to FITSBITS is still broken | William Pence | FITS | 0 | May 31st 06 07:21 PM |
[fitsbits] fitsbits and spam (test) | Lucio Chiappetti | FITS | 1 | March 22nd 04 05:52 PM |