Creates series of raster tiles for use in web mapping applications such as Bing™ Maps, Google Maps™, or Web Map Tile Service. Tiles are produced at varying zoom levels, size, and resolution.

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Typical Uses

  • Preparing raster data for use in a web mapping application

How does it work?

The WebMapTiler accepts raster features, and "pyramids" them - resampling and tiling them as necessary to produce a set of raster tiles appropriate for different zoom levels as required by various web mapping tile schemes.

The minimum and maximum zoom level may be specified, or left unset to produce the minimum and maximum level supported by the resolution and size of the input raster(s).

Tile size may be specified for some Tile Schemes. Various methods are available for interpolation of pixel values during resampling.

Attributes may be added to the output tiles to record zoom level, tile position, original raster index, number of tiles produced, and Quadkey (used for quad-tree based tile schemes).

This transformer is unaffected by raster band and/or palette selection.

Tile Schemes



Used for


Tile Size

Zoom Levels


Google Maps, Bing Maps, Web Map Tile Service, and ArcGIS.

EPSG:3857 (Spherical Mercator)

256x256 pixels

0 to 23


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, and so on. The number of tiles is increased accordingly - 1 tile, 4 tiles, 16 tiles, and so on.


Web Map Tile Service


256x256 pixels

0 to 18


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, and so on.


Web Map Tile Service



0 to 20


Spacing is defined in degrees for each level.





0 to 17


This scheme defines a spacing in degrees for each level, as follows:

*Incoming rasters that are not in the required projection will be reprojected by the transformer before tiling is carried out.


Usage Notes

  • To resample rasters using zoom levels and positions that are not tied to one of these web mapping tile schemes, consider using the RasterPyramider.
  • Attributes can be used for output file naming - for example the output feature type name can be set to the Quadkey attribute value.
  • Generally, when writing out the rasters generated by this transformer, one would set the destination feature type name to be the quadkey value for Bing Maps or a combination of the zoom level, tile column, and tile row for Google Maps. The PNGRASTER writer is recommended for the best results.
  • For best performance, rasters output by this transformer should be written in the order they are output. Changing the order (for example, by using Dataset Fanout or a Sorter transformer) may negatively impact performance. Alternatively, use a RasterCheckpointer after the WebMapTiler, but prior to the operation that changes the order.
  • When a tile contains areas outside the original raster coverage, an alpha band may be added to the tile to identify these areas. If this band is not desired, it may be removed with the RasterInterpretationCoercer transformer.

Choosing a Raster Transformer

FME has an extensive selection of transformers for working with raster data. They can be generally categorized as working with whole rasters, bands, cells or palettes, and those designed for workflow control or combining raster with vector data.

For information on raster geometry and properties, see Rasters (IFMERaster).


Input Ports

Output Ports


Editing Transformer Parameters

Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace. More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers. To access a menu of these options, click beside the applicable parameter. For more information, see Transformer Parameter Menu Options.

Defining Values

There are several ways to define a value for use in a Transformer. The simplest is to simply type in a value or string, which can include functions of various types such as attribute references, math and string functions, and workspace parameters. There are a number of tools and shortcuts that can assist in constructing values, generally available from the drop-down context menu adjacent to the value field.

Dialog Options - Tables

Transformers with table-style parameters have additional tools for populating and manipulating values.


Processing Behavior


Feature Holding


Dependencies None
Aliases VirtualEarthTiler
History This transformer was previously named the VirtualEarthTiler.

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Examples may contain information licensed under the Open Government Licence – Vancouver and/or the Open Government Licence – Canada.