Hi all,
 
I bumped into a big issue with being able to use OpenLayers for our project in 
regards on how the client wanted to use their web maps. 
 
They are using tile based services such as OSM an Google as base layers, thus 
also using spherical merc. for the map projection of the other map layers and 
the map display. I had noticed for a while that OpenLayers somehow magically 
calculates the map extent and zoom level when a zoom action is performed but 
that there is a restriction on which exact map extent you can zoom to - when 
using tile based layers with fixed zoom levels. Now that might work for many 
applications use cases but in the case of very tiny labels (and very many of 
those) this is a big issue (and maybe show stopper for us) namely that one 
can't zoom into any scale. The desired functionality is to zoom to a rectangle 
(rectangle zoom or shift+zoom action) and that the selected rectangle then will 
become about the map extent (plus /minus). I understand that works only if one 
is not using tile base layers with their fixed zoom scales...whereas with 
vectors or on the fly rendered layers this works really well. The reason the 
clients absolutely needs that is to maximize their tiny labels for editing 
purposes and at the same time being able to exactly define a map extent they 
are working on.
 
So one solution scenario I thought off would be to abandon the tiled layers 
altogether and use "on the fly rendering" of our own background layers.
One question I have is the following: could we work around  this functional 
behavior in OpenLayers (the tiled base layers stopping us to zoom to any map 
extent) when I add a dummy base layer (with no or minimal base map rendered on 
the fly but using the single tile option? Would that allow us to any scale and 
map extent. My guess is that it would not because the other base layers are 
still in the map document even though turned off ?
Is there any options I could turn on in OL or on the map and layers that 
dis/enables this behavior  (even if the base map layers would become really 
pixely that would be fine but we would nee to disable some of the magic 
OpenLayers map extent calculations ?
Any other advice we could make this work somehow ?
 
Thanks
Karsten

Karsten Vennemann

Terra GIS LTD
Seattle, WA  98112
USA 
www.terragis.net

_______________________________________________
Users mailing list
[email protected]
http://lists.osgeo.org/mailman/listinfo/openlayers-users

Reply via email to