[mapguide-internals] Tile maps...

[Paul Spencer]

One thing that should be possible in Fusion is to create an  
application definition that refers to two separate map definitions.   
This would be done in the map set as follows:

<MapSet>
   <MapGroup id="NamaimoEngineeringMap">
     <Map>
       <Name>NanaimoBaseMap</Name>
       <Type>MapGuide</Type>
       <SingleTile>false</SingleTile>
       <Extension>
         <ResourceId>Libary://path/to/tiled.MapDefinition</ResourceId>
       </Extension>
     </Map>
     <Map>
       <Name>EngineeringTheme</Name>
       <Type>MapGuide</Type>
       <SingleTile>true</SingleTile>
       <Extension>
         <ResourceId>Libary://path/to/EngineeringTheme.MapDefinition</ 
ResourceId>
       </Extension>
     </Map>
   </MapGroup>
</MapSet>

This would result in two OpenLayers layers being created, a tiled one  
that would be the baseMap (in OpenLayers terms) and an overlay that  
would be drawn using GETDYNAMICOVERLAYIMAGE and thus be transparent  
to the tiled layers underneath.

By possible, I mean it is theoretically possible to support this but  
I suspect that we will not have time to investigate this for the  
first integration.

Note that the intention is also to support other OpenLayers layer  
types in the MapGroup as overlays so you can also overlay WMS  
directly in the client (for instance) or use another tile source for  
the baseMap and use MapGuide as the overlay.

Cheers

Paul

On 14-Sep-07, at 7:35 PM, Trevor Wekel wrote:

> Hi Jason,
>
> A possible enhancement would be to define two map definitions for a
> "map".  The first definition would define the overlay/dynamic  
> layers and
> the second definition would be used only for the tiles.  I think they
> are separate layers in the new client framework so it may be  
> possible to
> implement.
>
> There would be some other implementation details like selection and
> query that would have to be worked out.  You may need to hit two  
> maps to
> find the selected/queried object.  This could be a little tricky but I
> don't think it would be impossible.  I suspect all the maps would also
> have to use the same coordinate system.
>
> Version 1.2.0 of the GETTILEIMAGE operation takes the resource id  
> of the
> map definition, the base map layer group name, the tile row and column
> and the scale index.  Authentication can be specified using  
> sessionid or
> username/password.
>
> A further enhancement to the "two layer" / "two map" approach would be
> to code up two different URLs for the overlay/dynamic and tiled  
> layers.
> This would allow us offload the base tiles to a completely separate
> server and web extensions.
>
> Thanks,
> Trevor
>
> -----Original Message-----
> From: mapguide-internals-bounces at lists.osgeo.org
> [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Jason
> Birch
> Sent: Friday, September 14, 2007 4:38 PM
> To: MapGuide Internals Mail List
> Subject: [mapguide-internals] Tile maps...
>
> Hi all,
>
> I've been thinking (not a good sign) about how tile maps are  
> implemented
> in MapGuide.  I'm seeing some real limitations on how useful this is
> going to be for me because of the association of tile sets with  
> specific
> maps.
>
> With the new Fusion framework, I intend to have several dozen maps
> (themes), each using one of three tile set definitions.  With the
> current inclusion of tile groups in map definitions, this means that
> I'll have to have separate copies of these tile groups for each one of
> my maps.
>
> I would really like to see some way of abstracting tile groups from  
> map
> definitions.  Either through a new resource type that defines the tile
> group, or by allowing tiled maps to be referenced from regular maps,
> rather than redefined in each one.
>
> Thoughts?
>
> Jason
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|Paul Spencer                          pspencer at dmsolutions.ca    |
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|Chief Technology Officer                                         |
|DM Solutions Group Inc                http://www.dmsolutions.ca/ |
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