[Mapserver-users] how to restrict layers based on location?

[Ed McNierney]

Dana et al. -

It's a rather cheesy solution, but you can also put the high-quality
layers on top of everything else, and have an opaque polygon just
underneath the high-quality layers that just matches their footprint.
This, of course, means you still draw the low-quality data first and
then obliterate it, but it would give you some sort of solution.

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
Phone: (978) 251-4242  Fax: (978) 251-1396
ed at topozone.com


-----Original Message-----
From: Dave McIlhagga [mailto:mcilhagga at dmsolutions.ca] 
Sent: Tuesday, February 18, 2003 9:50 PM
To: Dana Quinn
Cc: mapserver-users at lists.gis.umn.edu
Subject: Re: [Mapserver-users] how to restrict layers based on location?

We haven't actually done this, but I have thought about this problem in 
the past since it is relevant to us as well.  I'd love to hear if anyone

has had any success solving this.

One thought would be to clip the low quality data to remove the region 
of high quality and show this layer in addition to the high quality when

zoomed in but not the low quality where it intersects with the city.

If you want to use the low quality data all the time when you're zoomed 
out -- you can just have this layer included twice and set visibility 
scales such that the complete layer is shown at small scales, and the 
one with the hole in it is shown at zommed in scales.

A thought.
Dave


Dana Quinn wrote:
> 
> Hi - I have a problem I'm not sure how to solve
> within the mapfile.  I received high quality
> data for one of the cities that display in our
> application often.  I'd like to define a layer
> that uses this high quality data when displaying
> parts of this city, but uses the lower quality data
> when not displaying parts of the city.
> 
> I guess getting the high quality data to NOT display
> outside of the city isn't a problem, since the data
> doesn't exist for locations outside of the city,
> but I don't want the low quality data to show up
> along with the high quality stuff in the city.
> Is there a way to restrict what displays in the
> way I've described in the mapfile?  I couldn't
> really find any way to do this in the
> documentation.
> 
> dana
> 


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