[ka-Map-users] max_extents and EXTENT

[ramesh karra]

Thank you very much Tim!

Thank you for your explanation, I think I understand
the issue now. With some trial and error, I was able
to  determine the correct Maximum scale and extents.

Is there a better way to determine these values other
than trial and error? i.e., for a given extent, is
there a formula to determine exact maximum scale value
for a given display image size (of Width x Height)?

Thanks
Ramesh

--- Tim Schaub <tim at commenspace.org> wrote:

> 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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