[mapserver-users] turning on layers at a particular zoom level
Bill Thoen
bthoen at gisnet.com
Wed Sep 2 19:26:13 PDT 2009
sunny74 wrote:
> Hi,
>
> Thanks for ur reply.
> 1)What is the syntax for send request against a Group?
> 2)If I just write the name of the group within layer then will it be placed
> against the group?
> 3) What is the syntax for checking the zoom level of a map so that once a
> zoom level is reached I can call a group of layers?
>
1. You call it just like you do a layer. Just use the group name instead
of the file name.
2. Yes.
3. Just make separate LAYERs as you do normally, but do a set for each
scale zone, and then assign MAX ansd MIN SCALEDENOM for each one so that
when you only one set is active at any scale. (i.e., don't overlap scale
intervals)
I don't know happens at the transition points though. For example,
suppose you have your large scale symbology visible from a MINSCALEDENOM
of 1 to a MAAXSCALEDENOM of 100,000. Then at 100,000, your small scale
symbology layers take over. But what happens at 100,000? Do you get both
layer sets, or neither? Or does it do something clever like
MINSCALEDENOM starts right on the value and up, while the MAXSCALEDENOM
goes up to, but never equals the specified value?
Maybe while you're at it, could you check that and let us know?
Also, you ought to look this over: http://www.mapserver.org/mapfile/ In
particular, check out MIN and MAXSCALEDENOM under "LAYER".
Good luck!
- Bill Thoen
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