Reduced waterbodies as raster masks

Raster files representing the global waterbodies reduced in data volume for very efficient plain color rendering at low zoom levels.


These files are generated from the OpenStreetMap data of inland surface water and the coastline water polygons. The process used to generate these files produces both a raster and a polygon vector representation. Here you can find the raster version, the polygon files are available on a separate page.

This process is specific to the map projection used as well as the rendering resolution - currently this is available only in Mercator projection and for Mercator zoom levels 0 to 6 at a resolution of 256×256 pixel per tile.

The raster mask is made available as a single channel grayscale image with 8 bit per pixel and covers the whole map area. Internally it stores the data in tiled form (GDAL creation option TILED=YES) for efficient access to subsets of the data.


Separate raster files are produced for different classes of surface water.

  • An ocean mask representing areas mapped as coastline in OpenStreetMap.
  • A lakes mask representing the lakes and other bodies of standing water.
  • A river mask representing river and artificial canal areas.

The lakes and river masks are not suited to be rendered alone without the ocean data. Oceans and lakes together can however be used without the rivers if desired.

Using this data

To use this data in an OpenStreetMap based map download the raster files below, include them as separate layers in your map style, each file specifically for the zoom level it is meant for and limit use of the normal full resolution waterbody and ocean polygon data to the higher zoom levels. Not all rendering engines support using raster masks in rendering and those which do (like Mapnik with the RasterColorizer feature) are usually limited in styling options. For more flexibility you can use the polygon version. You should render the lakes above the rivers and the ocean above the lakes.

See also

Reduced waterbodies as polygons · Generalized coastline data · Ocean polygons


3 MB
Format: geotiff, Projection: Mercator, Last update: 2019-04-24 18:10
Ocean raster masks
7 MB
Format: geotiff, Projection: Mercator, Last update: 2019-04-24 18:10
Lake raster masks
2 MB
Format: geotiff, Projection: Mercator, Last update: 2019-04-24 18:10
River raster masks


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