[ka-Map-users] max_extents and EXTENT

Tim Schaub tim at commenspace.org
Wed Jun 7 11:17:04 EDT 2006


Hey Ramesh-
 
> Sorry for not mentioning that my EXTENT and max_extents are 
> exactly same! In that case I do not expect any difference in 
> the behavior!

I should have mentioned that both EXTENT and max_extents can both be
overridden by scale.  

It could be that I am misunderstanding your problem, but I'm guessing
that your largest scale (in mapserver terms) forces ka-Map to render an
area larger than your EXTENT (and max_extents).  If this is the case,
your EXTENT will be centered in the map viewport - but the viewport will
show an area beyond your EXTENT (and you should not be able to pan
around due to max_extents).  When you zoom in to your next scale, you
can no longer pan to the area outside of your EXTENT because of your
max_extents.

So, the bottom line is that you'll always be able to specify a scale
that violates your EXTENT and max_extents.  Note that this is a
dangerous practice (to specify a scale that requires tiles to be
rendered outside of your EXTENT) if you are relying on pre-caching
tiles.  The pre-caching script doesn't know how big your viewport is
going to be, so it assumes that you don't need more than a 1 metatile
buffer around your EXTENT or max_extents - if specified.

Tim

> 
> Ramesh
> 
> --- Tim Schaub <tim at commenspace.org> wrote:
> 
> > Hey Ramesh-
> > 
> > > I have a question regarding max_extents METADATA.
> > I have both
> > > EXTENT and METADATA max_extents defined in my map
> > file. At
> > > the highest zoom level(maximum scale), the map
> > shows a point
> > > X which is very close to the left border of
> > 'max_extents' I
> > > have defined. But when I zoom-in one level I
> > cannot see this. 
> > > Basically, I cannot drag that far left. Any ideas
> > on why this
> > > could be happening?
> > 
> > The max_extents METADATA option does not override your 
> scale settings.
> > So, if you have a max_extent defined that is smaller than 
> the extent 
> > of the map at your highest zoom level (at some browser 
> window size), 
> > ka-Map will still display the area outside the max_extents.
> >  So, the zoom level
> > (scale) has precedence when there is a conflict.
> > 
> > When you zoom in a bit, you are restricted in panning by 
> max_extents.
> > 
> > Let me know if you think something else is going on.
> > 
> > Tim
> > 
> > > 
> > > Thanks
> > > Ramesh
> > > 
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