comp.lang.idl-pvwave archive: archive » Re: Fractional Pixels Origin?

Home » Public Forums » archive » Re: Fractional Pixels Origin?

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: Fractional Pixels Origin? [message #47642 is a reply to message #47547]

Thu, 16 February 2006 23:50

Wayne Landsman
Messages: 117
Registered: January 1997

Senior Member

> I must be the only one *reading* Wayne's article. :-(
>
> Let me quote it again:
>
> "I'll say that the FITS convention is
> that [0,0] locates the center of the pixel."
>
> This whole thing just get curiousier and curiousier. :-)

Well, you must not take Wayne too literally. The correct statement is that
the FITS convention is that [1,1] locates the center of the pixel. My
conversion of the "first pixel is [1,1]" in FITS (or FORTRAN) to "first
pixel is [0,0]"
of IDL is so automatic that I hardly think about it, and I was just pointing
out that in FITS an integer value refers to the center of the pixel (whereas
in a "ruler" convention it refers to a corner of a pixel).

The main reason this matters in astronomy is for conversion between the X,Y
pixel centroid of a star to longitude, latitude. So I suppose the
poster's original question is also relevant for the MAP_PROJ_INVERSE,
MAP_PROJ_FORWARD routines in IDL.

--Wayne

Report message to a moderator

[Message index]

		Re: Fractional Pixels Origin? By: David Fanning on Thu, 16 February 2006 21:15
		Re: Fractional Pixels Origin? By: Greg Hennessy on Thu, 16 February 2006 20:20
		Re: Fractional Pixels Origin? By: David Fanning on Thu, 16 February 2006 16:02
		Re: Fractional Pixels Origin? By: JD Smith on Thu, 16 February 2006 14:48
		Re: Fractional Pixels Origin? By: rm on Thu, 16 February 2006 06:24
		Re: Fractional Pixels Origin? By: Craig Markwardt on Wed, 15 February 2006 14:28
		Re: Fractional Pixels Origin? By: Wayne Landsman on Wed, 15 February 2006 13:31
		Re: Fractional Pixels Origin? By: David Fanning on Wed, 15 February 2006 13:03
		Re: Fractional Pixels Origin? By: JD Smith on Fri, 17 February 2006 13:25
		Re: Fractional Pixels Origin? By: mmiller3 on Fri, 17 February 2006 05:36
		Re: Fractional Pixels Origin? By: Greg Hennessy on Fri, 17 February 2006 05:06
		Re: Fractional Pixels Origin? By: Wayne Landsman on Thu, 16 February 2006 23:50

Previous Topic:	naming PS plots: variable+ string?
Next Topic:	IDLWAVE 6.0 -- idlwave.org

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Wed Oct 08 11:09:43 PDT 2025

Total time taken to generate the page: 0.00500 seconds