[Mapserver-users] default extent

[Daniel Morissette]

Jan Hartmann wrote:
> 
> I put a request in Bugzilla to let a mapfile's extent default to the
> bounding box of all layers combined. This would come in very handy for
> peaple starting with a bunch of GIS- and raster-files they are not
> acquainted with. Setting a false extent will generally produce a blank
> map. When one could leave out extent altogether, something would be
> visible in any case (provided STATUS DEFAULT is set of course -:) ),
> though probably not at the expected position or scale.
> 

Note that this feature will come with a performance cost, which may be
huge for some layer types... so the documentation should be clear on the
fact that setting explicit extents in the mapfile is still very strongly
recommended.  (I would personally have opted for creating a command-line
utility that would scan all layers in a mapfile and report the extents.)

For instance, this will be very slow with OGR CONNECTIONs to ASCII file
formats, or even some binary formats that don't carry any extents
information in the file header.  It will also be slow with connections
to spatial databases since the databases will have to evaluate the SQL
query in order to return the extents.  Finally, I'm not even sure how
this lack of extents would/should be handled in the case of WMS or WFS
layers.

> 
> BTW I saw that some items in Bugzilla were put in a language vaguely
> reminiscent of French, e.g:
> 
> "J'ai roule mapserver 3.5 (avec la getgeatureinfo) et voici les memory
> leaks reportes" (bug 42)
> 
> Is this native Canadian?
> 

I'm not sure what you meant by native Canadian, but this is not written
in any official language, it's simply an unfortunate mix of French and
English.  Since we often don't know of a good French equivalent to
describe some technical things then we'll sometimes just use an English
expression in the middle of a French sentence, or switch back and forth
between languages without really noticing it.

FYI the reason why this half-French half-English bug report ended up
there is that it comes from a note exchanged between me and Assefa which
was not initially intended to end up in a bug report, sorry if it lead
to any confusion.

Daniel
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 Daniel Morissette               morissette at dmsolutions.ca
 DM Solutions Group              http://www.dmsolutions.ca/
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