[Geoserver-users] "No Data" tiles in TMS

Jonathan_Moules2 · April 29, 2013, 12:22pm

Hi List,
Is it possible to get GeoServer to return a sort of “no data” tile in response to TMS requests? As in, if there is no cached-tile, nor any data for that area to create a tile, it would return a stock default tile of my choosing?

Sort of like bing maps do here:
http://binged.it/Y8kHd0

Thanks,
Jonathan

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Andrea_Aime4 · April 30, 2013, 8:30am

On Mon, Apr 29, 2013 at 2:22 PM, Jonathan Moules <
jonathanmoules@anonymised.com> wrote:

Hi List,
Is it possible to get GeoServer to return a sort of "no data" tile in
response to TMS requests? As in, if there is no cached-tile, nor any data
for that area to create a tile, it would return a stock default tile of my
choosing?

Not with the current codebase.

Theoretically it would be possible to implement something like that, but
it's not entirely trivial,
as we don't do any preventive check of whether there is data on the area or
not before starting
to render (it would just slow down things).

That said, we already have some way to get notification that vector
features got rendered,
we'd have to use it to raise "no data" flags and compound it with some way
to discover
the lack of raster data.

Metatiling also makes things a bit more complicated, if you are rendering a
5x5 metatile that
only has data in the corner, the above approach won't tell you that, you'd
just know there
is some data somewhere inside the 5x5 block.

Cheers
Andrea

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Technical Lead

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-------------------------------------------------------

Jonathan_Moules2 · April 30, 2013, 8:41am

Thanks Andrea. I guess I’ll wait to see how many people complain about a “white background” when they’re in the middle of no-where before I throw our developer time at it.
Regards,

Jonathan

···

Hi List,
Is it possible to get GeoServer to return a sort of “no data” tile in response to TMS requests? As in, if there is no cached-tile, nor any data for that area to create a tile, it would return a stock default tile of my choosing?

Not with the current codebase.

Theoretically it would be possible to implement something like that, but it’s not entirely trivial,
as we don’t do any preventive check of whether there is data on the area or not before starting
to render (it would just slow down things).

That said, we already have some way to get notification that vector features got rendered,
we’d have to use it to raise “no data” flags and compound it with some way to discover
the lack of raster data.

Metatiling also makes things a bit more complicated, if you are rendering a 5x5 metatile that
only has data in the corner, the above approach won’t tell you that, you’d just know there
is some data somewhere inside the 5x5 block.