Syntax FACTORY_DEF WebMapTileFactory [FACTORY_NAME ] [INPUT FEATURE_TYPE [ ]* []*]* [TILE_SCHEME (GlobalCRS84Scale|GlobalCRS84Pixel|GoogleCRS84Quad|GoogleMapsCompatible)] [MIN_ZOOM_LEVEL ] [MAX_ZOOM_LEVEL ] [TILE_NUM_ROWS ] [TILE_NUM_COLUMNS ] [INTERPOLATION_TYPE_NAME (nearestneighbor|bilinear| bicubic|average4|average16)] [QUADKEY_ATTRIBUTE ] [ZOOM_LEVEL_ATTRIBUTE ] [TILE_COLUMN_ATTRIBUTE ] [TILE_ROW_ATTRIBUTE ] [RASTER_INDEX_ATTRIBUTE ] [NUM_TILES_ATTRIBUTE ] [OUTPUT TILES FEATURE_TYPE [ ]* []*]* Overview This factory is used to create a series of image tiles that can be utilized by web mapping applications such as Bing Maps, Google Maps, or Web Map Tile Service. This is done by resampling rasters to various different resolutions and then splitting them into tiles. The TILE_SCHEME clause specifies a method for tiling up data. This controls factors like the coordinate system, tile size, spacing, etc. See the Tile Scheme section for more details. The MIN_ZOOM_LEVEL and MAX_ZOOM_LEVEL clauses specify the zoom levels for which tiles will be generated. The exact meaning of a zoom level depends on the tile scheme, but in general a higher zoom level uses more pixels to cover the same area (i.e. more tiles will be generated). Note: Tiles will not be generated if the input raster covers less than 1 row and 1 column at a particular zoom level, regardless of the value of MIN_ZOOM_LEVEL. If MAX_ZOOM_LEVEL is unspecified, the maximum zoom level will be the smallest zoom level such that the resampled raster has more rows or columns than the original raster. The TILE_NUM_ROWS and TILE_NUM_COLUMNS clauses specify the tile size for tile schemes that support user-defined sizes. The INTERPOLATION_TYPE_NAME clause specifies the interpolation method to use when resampling to produce the different levels of detail. This clause is optional; it defaults to NEARESTNEIGHBOR. If specified, the QUADKEY_ATTRIBUTE, ZOOM_LEVEL_ATTRIBUTE, TILE_COLUMN_ATTRIBUTE, and TILE_ROW_ATTRIBUTE keywords name attributes that will be added to output features. Quadkeys are used by Bing Maps to uniquely identify a single tile at a particular level of detail. Note that this attribute will only be created for quad-tree based tile schemes (GoogleMapsCompatible and GoogleCRS84Quad). The zoom level, tile column, and tile row attributes are an alternative way to uniquely identify a tile which can be used by Google Maps or other web map applications. Generally, when writing out the rasters generated by this transformer, one would fanout the destination feature type on the quadkey for Bing Maps, or a combination of the zoom level, tile column, and tile row for Google Maps. The PNGRASTER writer is recommended for writing tiles. If the RASTER_INDEX_ATTRIBUTE clause is specified, an attribute will be added to each output tile that identifies which raster it was created from. This index is zero-based, so all tiles created from the first input raster will have a value of 0, all tiles created from the second input raster will have a value of 1, etc. If the NUM_TILES_ATTRIBUTE clause is specified, an attribute will be added to each output tile that specifies the total number of tiles created from the input raster, across all zoom levels. This factory accepts only features that have raster geometry and is unaffected by raster band and/or palette subselection. Attributes will be carried across from the INPUT features to the respective TILES features. Tile Schemes GoogleMapsCompatible This scheme is used by Google Maps and Bing Maps. - Input rasters are required to be in the EPSG:3857 coordinate system. - Tiles are always 256x256 pixels. - At level 0, the entire world is represented by a 256x256 pixel tile. Each level increases the number of rows and columns by a factor of two: level 1 is 512x512, level 2 is 1024x1024, etc. Level 23 is the highest level of detail. GoogleCRS84Quad This scheme is used by Web Map Tile Service. - Input rasters are required to be in the LL84 coordinate system. - Tiles are always 256x256 pixels. - At level 0, the entire world is represented by a 256x256 pixel tile (where the first and last 64 rows of the tile are blank). Each level increases the number of rows and columns by a factor of two: level 1 is 512x512, level 2 is 1024x1024, etc. Level 18 is the highest level of detail. GlobalCRS84Scale This scheme is used by Web Map Tile Service. - Input rasters are required to be in the LL84 coordinate system. - Tiles may have a user-defined size. - This scheme defines a spacing in degrees for each level, as follows: Level Spacing (degrees) 0 1.25764139776733 1 0.628820698883665 2 0.251528279553466 3 0.125764139776733 4 6.28820698883665e-2 5 2.51528279553466e-2 6 1.25764139776733e-2 7 6.28820698883665e-3 8 2.51528279553466e-3 9 1.25764139776733e-3 10 6.28820698883665e-4 11 2.51528279553466e-4 12 1.25764139776733e-4 13 6.28820698883665e-5 14 2.51528279553466e-5 15 1.25764139776733e-5 16 6.28820698883665e-6 17 2.51528279553466e-6 18 1.25764139776733e-6 19 6.28820698883665e-7 20 2.51528279553466e-7 GlobalCRS84Pixel This scheme is used by Web Map Tile Service. - Input rasters are required to be in the LL84 coordinate system. - Tiles may have a user-defined size. - This scheme defines a spacing in degrees for each level, as follows: Level Spacing (degrees) 0 2 1 1 2 0.5 3 0.333333333333333 4 0.166666666666667 5 8.333333333333333e-2 6 3.333333333333333e-2 7 1.666666666666667e-2 8 8.333333333333333e-3 9 4.166666666666667e-3 10 1.388888888888889e-3 11 8.333333333333333e-4 12 2.777777777777778e-4 13 1.388888888888889e-4 14 8.333333333333333e-5 15 2.777777777777778e-5 16 8.333333333333333e-6 17 2.777777777777778e-6 Output Tags The WebMapTileFactory supports the following output tag. TILES Output tiles created from the input feature(s).