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

sunny74 sb.ray at hotmail.com
Sun Sep 6 15:11:14 EDT 2009


Hi Bill,

Thanks for your reply.

I am now loading the layers in groups instead of individually.
First I am loading the base layer followed by 4 groups of layers, first
group contains 2 while others contain 3 each.

But the problem now is that at PageLoad for the first time the layers of
group1 are not visible because it is getting overlapped by the other layers.
The other layers are also not visible bec' they are mandated to be visible
at higher zoomin levels because of max/min scaledom.

Now if I load the group1 layers last then not only is it visible at initial
zoom level but also at higher zoom levels bec' in that case it is
overlapping the other layers mandated to be visible at that level.

So how to tackle the problem.

Can it be solved by changing the z-index of the first group at initial
PageLoad.

Pls provide some solution to this problem.


Bill Thoen wrote:
> 
> 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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> mapserver-users at lists.osgeo.org
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> 
> 

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