[Tile-serving] [mod_tile] Bleed (#29)

[Paul Norman]

> @plepe you are right that the interplay of buffer-size and avoid-edges is critical. It is my sense that avoid-edges should relate to the real edges and not the buffered edge. If you feel differently or see use cases for changing this then please create/discuss on a mapnik ticket.

It is essential for tiles that mapnik does nothing special for the meta-tile boundaries. I could open up a mapnik ticket, but the more I think about this the more I wonder if @plepe's solution is the right one and the tile-handling daemon should just ask mapnik for a larger image.

You want mapnik to handle feature near the tile edges identically on multiple tiles, which means that a a feature just inside and a feature just outside need to be handled the same way. If you handle it differently then something will be rendered in one meta-tile, but not in the buffer/bleed region outside of the other meta-tile, which can lead to inconsistencies.

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Reply to this email directly or view it on GitHub:
https://github.com/openstreetmap/mod_tile/pull/29#issuecomment-22846622
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