[mapserver-users] Label text always clipped by tiles

[Mike Stoddart]

I set metaBuffer to 20 (I have SIZE=10) and there's no difference.

metaTile="yes"
metaBuffer=20


Thanks
Mike

On Wed, Jan 26, 2011 at 11:12 AM, Jean-François Gigand
<jean-francois at gigand.fr> wrote:
> I'm not sure if the issue is related to the renderer.
> My issue is met on both AGG and GD, and is perfectly understandable:
> MapServer requests vector data only within the BBOX. So the rendered
> image misses symbols which are drawn from outside feature, even though
> they should be visible on the image because of their size.
> Same for labels: they are incomplete because missing on the tiles
> whose BBOX do not contain the geometry they were created from.
>
> TileCache is the solution. Set "metaBuffer" to the double of the maximum
> size in pixels of your symbols.
>
> A youger project following TileCache concepts is mod-geocache. It
> seems to support metaBuffer and metaTiles (haven't tested it yet):
> http://code.google.com/p/mod-geocache/
>
> Jeff
>
> 2011/1/26 Mike Stoddart <stodge at gmail.com>:
>> Thanks Jean-François, I'll try your solution.
>>
>> Is this clipping issue only a problem in the AGG renderer or does the
>> original GD(?) renderer have the same problem.
>>
>> Thanks
>> Mike
>>
>> On Wed, Jan 26, 2011 at 11:00 AM, Jean-François Gigand
>> <jean-francois at gigand.fr> wrote:
>>> Hi,
>>>
>>> I met the edge issue when I had to produce statistics maps with
>>> proportional symbols.
>>>
>>> TileCache addressed the issue indeed, with the "metaBuffer" option
>>> (see http://tilecache.org/docs/README.html#configuration).
>>> It means that MapServer will be called to generate larger tiles which
>>> are then cropped by TileCache, which has a time processing cost.
>>>
>>> The "metaTile" is meant to optimize this by rendering multiple tiles
>>> as a single one.
>>>
>>> Jeff
>>>
>>> 2011/1/26 Gregor at HostGIS <gregor at hostgis.com>:
>>>>> I was using TileCache, but I switched it off to debug this problem. If
>>>>> TileCache generates larger tiles, will there still be clipped labels?
>>>>> Just fewer clipped labels? I don't think this is a workable solution
>>>>> for me, but if I have the time I'll try it.
>>>>
>>>> Correct; there would be FEWER labels clipped (if you force them and allow
>>>> partials) or missing (if you disallow partials).
>>>>
>>>> How many fewer, depends on how large you make your meta-tiles. If they're
>>>> 5x5, that's a significant reduction in the number of tile edges. If you
>>>> really turn up your MAXSIZE in your mapfile, you could potentially make
>>>> 10x10 meta-tiles; that's 1% as many tile edges.
>>>>
>>>> You could also make your tiles larger. If you have 512x512 tiles, and 10x10
>>>> meta-tiles, that's a HUGE reduction in the number of tile edges over single
>>>> 256x256 tiles.
>>>>
>>>> The only method I know that would eliminate ALL tile-edge artifacts, would
>>>> be to eliminate tiling, e.g. singleTile:true in OpenLayers. Not that that's
>>>> a great solution either, but it is sometimes the only way.
>>>>
>>>> --
>>>> HostGIS, Open Source solutions for the global GIS community
>>>> Greg Allensworth - SysAdmin, Programmer, GIS Person, Security
>>>>   Network+   Server+   A+   Security+   Linux+
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>>>
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