Difference between revisions of "Tiling"
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| − | This page belongs to the [http://lists.osgeo.org/mailman/listinfo/tiling | + | This page belongs to the [http://lists.osgeo.org/mailman/listinfo/tiling tiling mailinglist] which has been initiated after the Foss4g 2010 BoF on tiling. At the BoF it became clear that there is a need for more advanced cache management in the various tile-cache programs. |
== Problems == | == Problems == | ||
| − | * Tiling produces too many files | + | * Tiling produces too many files to handle |
* There is need for usage-statistics on tiles | * There is need for usage-statistics on tiles | ||
* A smarter way for seeding is needed | * A smarter way for seeding is needed | ||
* A smarter way for deleting tiles is needed | * A smarter way for deleting tiles is needed | ||
| + | * GetFeatureInfo is needed (mainly bypass the requst to the backend) | ||
| + | |||
| + | == Possible solutions == | ||
| + | GeoWebCache uses a paging algorithm to manage the statistics of the tiles. Tiles are grouped in page-files and the deeper the zoomlevel the more files are in the page file. Usage statistics are handled at the page-file level, not per tile. | ||
| + | |||
| + | OSM uses special PNG files where 8x8 tiles are grouped with a special header to locate the individual tiles. This way the number of files are reduced. It is not clear of 8x8 is optimal. | ||
| + | |||
| + | Empty/single color tiles should be recognised and linked to one file. Mapproxy uses a color lookup algorithm to check if there is only one color per tile. | ||
| + | |||
| + | Use polygons as input for tileseeding. | ||
| + | |||
| + | To optimise I/O on the mapserver, use depth traversing tileseeding. | ||
Latest revision as of 22:19, 12 September 2010
This page belongs to the tiling mailinglist which has been initiated after the Foss4g 2010 BoF on tiling. At the BoF it became clear that there is a need for more advanced cache management in the various tile-cache programs.
Problems
- Tiling produces too many files to handle
- There is need for usage-statistics on tiles
- A smarter way for seeding is needed
- A smarter way for deleting tiles is needed
- GetFeatureInfo is needed (mainly bypass the requst to the backend)
Possible solutions
GeoWebCache uses a paging algorithm to manage the statistics of the tiles. Tiles are grouped in page-files and the deeper the zoomlevel the more files are in the page file. Usage statistics are handled at the page-file level, not per tile.
OSM uses special PNG files where 8x8 tiles are grouped with a special header to locate the individual tiles. This way the number of files are reduced. It is not clear of 8x8 is optimal.
Empty/single color tiles should be recognised and linked to one file. Mapproxy uses a color lookup algorithm to check if there is only one color per tile.
Use polygons as input for tileseeding.
To optimise I/O on the mapserver, use depth traversing tileseeding.