Re: [Geoserver-devel] R: Planning the next few months (warning, long mail)

[Andrea A. <aa...@op...>]

Fabio Da Soghe ha scritto:
> Hello list.
> 
> I'm reading this thread with much interest. In the webmapping
> application my company is building (based on GeoServer), we're sadly
> discovering the issue about tiled rendering (label moving near tile
> boundary and cell and text cutting).
> 
> Tiled rendering is very "cool" and definitively a must for us (for
> both performance and usability reasons), but these problem seems to
> put a stop on this road.
> 
> Directly supporting it in GeoServer (via WMS-C or TMS) would be
> great, but in the meantime we're guessing if there could be some
> workaround that let one use the tile mechanism and still keep getting
> correct maps (without at least ugly cut cells).

Yeah, I hear you. We'll be hopefully doing something in the next
weeks, since I'm almost done with the first iteration of the
versioned data store.

> Has anybody some hint in this direction? Maybe through a patch to
> GeoServer, as was discussed in this list some time ago (about a
> possible vendor-specific option in the SLD with which to get no
> cross-tile label, for example)?

Well, this requires two things:
* a buffer area, that is, to make sure every line, symbol and label
   is properly rendered we have to expand the rendering area of the
   tile. A smarter way, once we have server side tile caching, is
   the metatile approach TileCache is using, that is, render say
   6 adjacent tiles to avoid paying a big extra rendering effort
   due to the buffer.
* avoid having labels consider the rendered bbox and jump around,
   the renderer should consider a big seamless surface instead,
   since this is what tiling is about, build a seamless surface
   out of smaller images.

As said, I hope to get at least some of this changes in by
the end of January, but I can make no promises.

Cheers
Andrea