[mapserver-users] turning on layers at a particular zoom level

[Bill Thoen]

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