nonsquare pixels (was: Questions about extents and projections)

[Frank Warmerdam]

On 2/3/06, Brian Peschel <brianp at occinc.com> wrote:
> Well, I am not using the WMS dispatcher, so I see in msPrepareImage()
> where the extents are changing for the 'fudge'.  I do want non-square
> pixels.  So, I guessed that if I call:
>     msSetConfigOption(map, "MS_NONSQUARE", "YES");
> before msDrawMap() I would get the exact extent I requested.  However,
> the extents are still changing, so I am missing another spot where the
> extents are changing.

Brian,

I think this should be sufficient.

> My extent before calling msDrawMap is
>   EXTENT -113.981498074503 50.7247102624229 -113.961752952407
> 50.7319757375771
> my extent after the call is:
>   EXTENT -113.981498074503 50.7226042699327 -113.961752952407
> 50.7340817300673
>
> whether I make the call to msSetConfigOoption() or not (I am using
> msSaveMap() before and after the call to msDrawMap() to get the
> extents).  My image is 609x354 pixels (width x height).
>
> My resulting images are also blank (just the background color from my
> map file).
>
> I am also running mapserver 4.6.2.  I see that 4.8.0 is out.  Would
> upgrading help here?

I don't think you will fine much difference between 4.6.2 and
4.8.1 in this regard, but of course it is more interesting for
the developers to debug if it is reproduced a recent version.

Would it be possible for you to submit a demonstration of
the problem via bugzillla?  You can assign it directly to me
since I am responsible for the messiness that is MS_NONSQUARE.

Best regards,
--
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent