Same Map tiles for different zoom levels.

[Vidyadhar]

Hi,

I have a requirement in my application where I have to use only certain zoom levels of the RadMap, levels 5 through 10. And am using a custom Map Provider inherited from TiledProvider class. I use a set of tiles extracted only for zoom levels 5 through 7. I want to know if I zoom in to a level greater than 7, will the Provider use the same tiles intended for zoom level 7. If not, is there a way I could use the zoom 7 tiles for higher zoom levels.

Thanks,
Vidyadhar.

[Andrey]

Hi Vidyadhar,

It depends on the implementation of your custom map provider. In the most common case provider will show images from level 7 on level 8 if there are not tiles for level 8. But image will be blurred, because tiles will be expanded.

Kind regards,
Andrey Murzov
the Telerik team

[Vidyadhar]

Andrey,

Thanks for the reply.
So does it mean, if the Provider doesn't find the tiles for a particular zoom level, it looks up for the tiles for zoom level below that. Is it recursive. I mean, say I've tiles for just zoom levels 5 through 7 and if I zoom in to level 9, then it would look for tiles for zoom 8 and if it doesn't find any tiles for zoom 8, would it look for tiles for zoom 7 and so on? I observe that my application is crashing when I load it at zoom levels 9 and 10. So wanted to get clarified about this?

I think my Map Provider is the most common way of building it. Here's the link of the process I followed to create my Map Provider, as suggested by Telerik, http://www.telerik.com/help/silverlight/radmap-howto-custom-provider.html. I customized the GetTile method to meet our needs. I calculate the quadkeys for the tiles using the Microsoft's Tile System,http://msdn.microsoft.com/en-us/library/bb259689.aspx. Once I get the quadkey I look for the corresponding file from the source directory and return the Uri for that tile.


Thanks,
Viddy.

[Andrey]

Hi Vidyadhar,

No, it doesn't. Map provider always look for the tiles for the particular zoom level. The tiles visualization engine works as reverse pyramid. When you zoom from level 7 (where you have tiles) to the level 8 (where you have not tiles) provider will look for the tiles for level 8. But since there are not tiles for level 8 you will see tiles from level 7.  

Greetings,
Andrey Murzov
the Telerik team