[mapserver-users] ScaleHint

[Doug Nebert]

Paul Ramsey wrote:
> 
> I have started exploring the WMS capability somewhat... I was wondering
> why the WMS does not provide a ScaleHint for layers which have
> explicitly defined min and max scales? What will the MapServer WMS do if
> a client does  GetMap on a layer using an extent which violates the
> maxscale? I am thinking in terms of writing a client which knows nothing
> about the WMS except there is a service there: in order to properly
> request scale-restricted layers, the ScaleHint is vital. Otherwise the
> client could request every contour in the province, when in fact
> contours should only be requested at a close-in zoom level.
> Thanks for the info,
> Paul
> 

Gee. I could use this functionality, too. The server already has the
capability of recognizing MAXSCALE and MINSCALE in the .map files.
It seems these could easily be coordinated, such that these 
properties could be exported to the capabilities statement and thus
would be respected if provided in the .map file. So I think this
is an easy thing to do if you don't treat scalehint as pure metadata
but is derived from MINSCALE MAXSCALE.

Doug.

> PS - Doesn't requiring the 'map' parameter violate the WMS spec? (I
> recognize the difficulty, however -- what is a service description
> absent a map file? Perhaps a simple wrapper example could be bundled.)


-- 
Douglas D. Nebert
Geospatial Data Clearinghouse Coordinator 
FGDC/GSDI Secretariat	Phone: +1 703 648 4151	Fax: +1 703 648-5755	
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