WMS -- Web Map Services

Driver short name

WMS

Build dependencies

libcurl

Accessing several different types of web image services is possible using the WMS format in GDAL.

Driver capabilities

Supports CreateCopy()

This driver supports the GDALDriver::CreateCopy() operation

Supports Georeferencing

This driver supports georeferencing

Supports VirtualIO

This driver supports virtual I/O operations (/vsimem/, etc.)

XML description file

Services are accessed by creating a local service description XML file -- there are examples below for each of the supported image services. It is important that there be no spaces or other content before the <GDAL_WMS> element.

<GDAL_WMS>

<Service name="WMS">

Define what mini-driver to use, currently supported are: WMS, WorldWind, TileService, TMS, TiledWMS, VirtualEarth or AGS. (required)

<Version>1.1.1</Version>

WMS version. (optional, defaults to 1.1.1)

<ServerUrl>http://host.domain.com/wms.cgi?</ServerUrl>

WMS server URL. (required)

<SRS>EPSG:4326</SRS>

Image projection (optional, defaults to EPSG:4326 in WMS and 102100 in AGS, WMS version 1.1.1 or below only and ArcGIS Server). For ArcGIS Server the spatial reference can be specified as either a well-known ID or as a spatial reference json object

<CRS>CRS:83</CRS>

Image projection (optional, defaults to EPSG:4326, WMS version 1.3.0 or above only)

<ImageFormat>image/jpeg</ImageFormat>

Format in which to request data. Paletted formats like image/gif will be converted to RGB. (optional, defaults to image/jpeg)

<Transparent>FALSE</Transparent>

Set to TRUE to include "transparent=TRUE" in the WMS GetMap request (optional defaults to FALSE).  The request format and BandsCount need to support alpha.

<Layers>modis%2Cglobal_mosaic</Layers>

A URL encoded, comma separated string of layers (required, except for TiledWMS)

<TiledGroupName>Clementine</TiledGroupName>

Comma separated list of layers. (required for TiledWMS)

<Styles></Styles>

Comma separated list of styles. (optional)

<BBoxOrder>xyXY</BBoxOrder>

Reorder bbox coordinates arbitrarily. May be required for version 1.3 servers. (optional) x - low X coordinate, y - low Y coordinate, X - high X coordinate, Y - high Y coordinate

</Service>

<DataWindow>

Define size and extents of the data. (required, except for TiledWMS and VirtualEarth)

<UpperLeftX>-180.0</UpperLeftX>

X (longitude) coordinate of upper-left corner. (optional, defaults to -180.0, except for VirtualEarth)

<UpperLeftY>90.0</UpperLeftY>

Y (latitude) coordinate of upper-left corner. (optional, defaults to 90.0, except for VirtualEarth)

<LowerRightX>180.0</LowerRightX>

X (longitude) coordinate of lower-right corner. (optional, defaults to 180.0, except for VirtualEarth)

<LowerRightY>-90.0</LowerRightY>

Y (latitude) coordinate of lower-right corner. (optional, defaults to -90.0, except for VirtualEarth)

<SizeX>2666666</SizeX>

Image size in pixels.

<SizeY>1333333</SizeY>

Image size in pixels.

<TileX>0</TileX>

Added to tile X value at highest resolution. (ignored for WMS, tiled image sources only, optional, defaults to 0)

<TileY>0</TileY>

Added to tile Y value at highest resolution. (ignored for WMS, tiled image sources only, optional, defaults to 0)

<TileLevel>0</TileLevel>

Tile level at highest resolution. (tiled image sources only, optional, defaults to 0)

<TileCountX>0</TileCountX>

Can be used to define image size, SizeX = TileCountX * BlockSizeX * 2TileLevel. (tiled image sources only, optional, defaults to 0)

<TileCountY>0</TileCountY>

Can be used to define image size, SizeY = TileCountY * BlockSizeY * 2TileLevel. (tiled image sources only, optional, defaults to 0)

<YOrigin>top</YOrigin>

Can be used to define the position of the Y origin with respect to the tile grid. Possible values are 'top', 'bottom', and 'default', where the default behavior is mini-driver-specific. (TMS mini-driver only, optional, defaults to 'bottom' for TMS)

</DataWindow>

<Projection>EPSG:4326</Projection>

Image projection (optional, defaults to value reported by mini-driver or EPSG:4326)

<IdentificationTolerance>2</IdentificationTolerance>

Identification tolerance (optional, defaults to 2)

<BandsCount>3</BandsCount>

Number of bands/channels, 1 for grayscale data, 3 for RGB, 4 for RGBA. (optional, defaults to 3)

<DataType>Byte</DataType>

Band data type, one of: Byte, Int16, UInt16, Int32, UInt32, Float32, Float64, etc.. (optional, defaults to Byte)

<DataValues NoData="0 0 0" min="1 1 1" max="255 255 255" />

Define NoData and/or minimum and/or maximum value for bands. nodata_values, min_values, max_values can be one single value, or a value per band, with a space separator between value

<BlockSizeX>1024</BlockSizeX>

Block size in pixels. (optional, defaults to 1024, except for VirtualEarth)

<BlockSizeY>1024</BlockSizeY>

Block size in pixels. (optional, defaults to 1024, except for VirtualEarth)

<OverviewCount>10</OverviewCount>

Count of reduced resolution layers each having 2 times lower resolution. (optional, default is calculated at runtime)

<Cache>

Enable local disk cache. Allows for offline operation. (optional but present in the autogenerated service file, cache is disabled when not present or if it is overridden with GDAL_ENABLE_WMS_CACHE=NO)

<Path>./gdalwmscache</Path>

Location where to store cache files. It is safe to use same cache path for different data sources. /vsimem/ paths are supported allowing for temporary in-memory cache. (optional, cf below Caching section for default value)

<Depth>2</Depth>

Number of directory layers. 2 will result in files being written as cache_path/A/B/ABCDEF... (optional, defaults to 2)

<Extension>.jpg</Extension>

Append to cache files. (optional, defaults to none)

<Type>file</Type>

Cache type. Now supported only 'file' type. In 'file' cache type files are stored in file system folders. (optional, defaults to 'file')

<Expires>604800</Expires>

Time in seconds cached files will stay valid. If cached file expires it is deleted when maximum size of cache is reached. Also expired file can be overwritten by the new one from web. Default value is 7 days (604800s).

<MaxSize>67108864</MaxSize>

The cache maximum size in bytes. If cache reached maximum size, expired cached files will be deleted. Default value is 64 Mb (67108864 bytes).

<CleanTimeout>120</CleanTimeout>

Clean Thread Run Timeout in seconds. How often to run the clean thread, which finds and deletes expired cached files. Default value is 120s. Use value of 0 to disable the Clean Thread (effectively unlimited cache size). If you intend to use very large cache size you might want to disable the cache clean or to use a much longer timeout as the time that takes to scan the cache files for expired cache files might be long. ("disabled" was the only option for GDAL <= 2.2; "120s" was the only option for 2.3 <= GDAL <= 3.1).

<Unique>True</Unique>

If set to true the path will appended with md5 hash of ServerURL. Default value is true.

</Cache>

<MaxConnections>2</MaxConnections>

Maximum number of simultaneous connections. (optional, defaults to 2). Can also be set with the GDAL_MAX_CONNECTIONS configuration option (GDAL >= 3.2)

<Timeout>300</Timeout>

Connection timeout in seconds. (optional, defaults to 300 or GDAL_HTTP_TIMEOUT, if specified)

<OfflineMode>true</OfflineMode>

Do not download any new images, use only what is in cache. Useful only with cache enabled. (optional, defaults to false)

<AdviseRead>true</AdviseRead>

Enable AdviseRead API call - download images into cache. (optional, defaults to false)

<VerifyAdviseRead>true</VerifyAdviseRead>

Open each downloaded image and do some basic checks before writing into cache. Disabling can save some CPU cycles if server is trusted to always return correct images. (optional, defaults to true)

<ClampRequests>false</ClampRequests>

Should requests, that otherwise would be partially outside of defined data window, be clipped resulting in smaller than block size request. (optional, defaults to true)

<UserAgent>GDAL WMS driver (http://www.gdal.org/frmt_wms.html)</UserAgent>

HTTP User-agent string. Some servers might require a well-known user-agent such as "Mozilla/5.0" (optional, defaults to "GDAL WMS driver (http://www.gdal.org/frmt_wms.html)"). When used with some servers, like OpenStreetMap ones, it is highly recommended to put a custom user agent to avoid being blocked if the default user agent had to be blocked.

<Accept>mimetype>/Accept>

HTTP Accept header to specify the MIME type of the expected output of the server. Empty by default

<UserPwd>user:password</UserPwd>

User and Password for HTTP authentication (optional).

<UnsafeSSL>true</UnsafeSSL>

Skip SSL certificate verification. May be needed if server is using a self signed certificate (optional, defaults to false).

<Referer>http://example.foo/</Referer>

HTTP Referer string. Some servers might require it (optional).

<ZeroBlockHttpCodes>204,404</ZeroBlockHttpCodes>

Comma separated list of HTTP response codes that will be interpreted as a 0 filled image (i.e. black for 3 bands, and transparent for 4 bands) instead of aborting the request. (optional, defaults to 204)

<ZeroBlockOnServerException>true</ZeroBlockOnServerException>

Whether to treat a Service Exception returned by the server as a 0 filled image instead of aborting the request. (optional, defaults to false)

</GDAL_WMS>

Starting with GDAL 2.3, additional HTTP headers can be sent by setting the GDAL_HTTP_HEADER_FILE configuration option to point to a filename of a text file with “key: value” HTTP headers.

Minidrivers

The GDAL WMS driver has support for several internal 'minidrivers', which allow access to different web mapping services. Each of these services may support a different set of options in the Service block.

WMS

Communications with an OGC WMS server. Has support for both tiled and untiled requests.

WMS layers can be queried (through a GetFeatureInfo request) with the gdallocationinfo utility, or with a GetMetadataItem("Pixel_iCol_iLine", "LocationInfo") call on a band object.

gdallocationinfo "WMS:http://demo.opengeo.org/geoserver/gwc/service/wms?SERVICE=WMS&VERSION=1.1.1&
                            REQUEST=GetMap&LAYERS=og%3Abugsites&SRS=EPSG:900913&
                            BBOX=-1.15841845090625E7,5479006.186718751,-1.1505912992109375E7,5557277.703671876&
                            FORMAT=image/png&TILESIZE=256&OVERVIEWCOUNT=25&MINRESOLUTION=0.0046653459640220&TILED=true"
                           -geoloc -11547071.455 5528616 -xml -b 1

Output:

Report pixel="248595" line="191985">
  <BandReport band="1">
    <LocationInfo>
      <wfs:FeatureCollection xmlns="http://www.opengis.net/wfs"
                                xmlns:wfs="http://www.opengis.net/wfs"
                                xmlns:gml="http://www.opengis.net/gml"
                                xmlns:og="http://opengeo.org"
                                xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                                xsi:schemaLocation="http://opengeo.org http://demo.opengeo.org/geoserver/wfs?service=WFS&version=1.0.0&request=DescribeFeatureType&typeName=og%3Abugsites http://www.opengis.net/wfs http://demo.opengeo.org/geoserver/schemas/wfs/1.0.0/WFS-basic.xsd">
        <gml:boundedBy>
          <gml:Box srsName="http://www.opengis.net/gml/srs/epsg.xml#26713">
            <gml:coordinates xmlns:gml="http://www.opengis.net/gml" decimal="." cs="," ts=" ">601228,4917635 601228,4917635</gml:coordinates>
          </gml:Box>
        </gml:boundedBy>
        <gml:featureMember>
          <og:bugsites fid="bugsites.40946">
            <gml:boundedBy>
              <gml:Box srsName="http://www.opengis.net/gml/srs/epsg.xml#26713">
                <gml:coordinates xmlns:gml="http://www.opengis.net/gml" decimal="." cs="," ts=" ">601228,4917635 601228,4917635</gml:coordinates>
              </gml:Box>
            </gml:boundedBy>
            <og:cat>86</og:cat>
            <og:str1>Beetle site</og:str1>
            <og:the_geom>
              <gml:Point srsName="http://www.opengis.net/gml/srs/epsg.xml#26713">
                <gml:coordinates xmlns:gml="http://www.opengis.net/gml" decimal="." cs="," ts=" ">601228,4917635</gml:coordinates>
              </gml:Point>
            </og:the_geom>
          </og:bugsites>
        </gml:featureMember>
      </wfs:FeatureCollection>
    </LocationInfo>
    <Value>255</Value>
  </BandReport>
</Report>

TileService

Service to support talking to a WorldWind TileService. Access is always tile based.

WorldWind

Access to web-based WorldWind tile services. Access is always tile based.

TMS

The TMS Minidriver is designed primarily to support the users of the TMS Specification. This service supports only access by tiles.

Because TMS is similar to many other 'x/y/z' flavored services on the web, this service can also be used to access these services. To use it in this fashion, you can use replacement variables, of the format ${x}, ${y}, etc.

Supported variables (name is case sensitive) are :

  • ${x} -- x position of the tile

  • ${y} -- y position of the tile. This can be either from the top or the bottom of the tileset, based on whether the YOrigin parameter is set to true or false.

  • ${z} -- z position of the tile -- zoom level

  • ${version} -- version parameter, set in the config file. Defaults to 1.0.0.

  • ${format} -- format parameter, set in the config file. Defaults to 'jpg'.

  • ${layer} -- layer parameter, set in the config file. Defaults to nothing.

A typical ServerURL might look like:
http://tilecache.osgeo.org/wms-c/Basic.py/${version}/${layer}/${z}/${x}/${y}.${format}
In order to better suit TMS users, any URL that does not contain "${" will automatically have the string above (after "Basic.py/") appended to their URL.

The TMS Service has 3 XML configuration elements that are different from other services: Format which defaults to jpg, Layer which has no default, and Version which defaults to 1.0.0.

Additionally, the TMS service respects one additional parameter, at the DataWindow level, which is the YOrigin element. This element should be one of bottom (the default in TMS) or top, which matches OpenStreetMap and many other popular tile services.

Two examples of usage of the TMS service are included in the examples below.

OnEarth Tiled WMS

The OnEarth Tiled WMS minidriver supports the Tiled WMS specification implemented for the JPL OnEarth driver per the specification at http://web.archive.org/web/20130511182803/http://onearth.jpl.nasa.gov/tiled.html.

Only the ServerUrl and the TiledGroupName are required, most of the required information is automatically fetched from the remote server using the GetTileService method at open time.

A typical OnEarth Tiled WMS configuration file might look like:

<GDAL_WMS>
    <Service name="TiledWMS">
    <ServerUrl>https://gibs.earthdata.nasa.gov/twms/epsg4326/best/twms.cgi?</ServerUrl>
    <TiledGroupName>MODIS Terra CorrectedReflectance TrueColor tileset</TiledGroupName>
    <Change key="${time}">2020-02-02</Change>
    </Service>
</GDAL_WMS>

The TiledWMS minidriver can use the following open options :

  • TiledGroupName -- The value is a string that identifies one of the tiled services available on the server

  • Change -- A <Key>:<Value> pair, which will be passed to the server. The key has to match a change key that the server declares for the respective tiled group. This option can be used multiple times, for different keys. Example: - Change=time:2020-02-02

These open options are only accepted if the corresponding XML element is not present in the configuration file.

VirtualEarth

Access to web-based Virtual Earth tile services. Access is always tile based.

The ${quadkey} variable must be found in the ServerUrl element.

The DataWindow element might be omitted. The default values are :

  • UpperLeftX = -20037508.34

  • UpperLeftY = 20037508.34

  • LowerRightX = 20037508.34

  • LowerRightY = -20037508.34

  • TileLevel = 21

  • OverviewCount = 20

  • SRS = EPSG:3857

  • BlockSizeX = 256

  • BlockSizeY = 256

ArcGIS REST API

Access to ArcGIS REST map service resource (untiled requests).

AGS layers can be queried (through a GetFeatureInfo request) with the gdallocationinfo utility, or with a GetMetadataItem("Pixel_iCol_iLine", "LocationInfo") call on a band object.

gdallocationinfo -wgs84 "<GDAL_WMS><Service name=\"AGS\"><ServerUrl>http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Specialty/ESRI_StateCityHighway_USA/MapServer</ServerUrl><BBoxOrder>xyXY</BBoxOrder><SRS>3857</SRS></Service><DataWindow><UpperLeftX>-20037508.34</UpperLeftX><UpperLeftY>20037508.34</UpperLeftY><LowerRightX>20037508.34</LowerRightX><LowerRightY>-20037508.34</LowerRightY><SizeX>512</SizeX><SizeY>512</SizeY></DataWindow></GDAL_WMS>" -75.704 39.75

Internet Imaging Protocol (IIP) (GDAL 2.1 and later)

Access to images served through IIP protocol. The server must support the JTL (Retrieve a tile as a complete JFIF image) extension of the IIP protocol.

If using the XML syntax, the ServerURL must contain the FIF parameter.

Otherwise it is also possible to use "IIP:http://foo.com/FIF=image_name" syntax as connection string, to retrieve from the server information on the full resolution dimension and the number of resolutions.

The XML definition can then be generated with "gdal_translate IIP:http://foo.com/FIF=image_name out.xml -of WMS"

Caching

Caching of remote pixel data is possible by setting a <Cache> element in the WMS (or WMTS) configuration file.

Before GDAL 3.9, if the <Path> sub-element of <Cache> was not specified, the directory of the cache was ./gdalwmscache (that is to say a gdalwmscache subdirectory of the current directory), unless the GDAL_DEFAULT_WMS_CACHE_PATH configuration option is specified.

Starting with GDAL 3.9, the directory of the cache is set according to the following logic (first listed criterion is prioritary over following ones):

  • Value of the <Path> sub-element of <Cache>, if specified.

  • ${GDAL_DEFAULT_WMS_CACHE_PATH} if GDAL_DEFAULT_WMS_CACHE_PATH is set.

  • ${XDG_CACHE_HOME}/gdalwmscache if the XDG_CACHE_HOME configuration option is set.

  • On Unix, ${HOME}/.cache/gdalwmscache if the HOME configuration option is set.

  • On Windows, ${USERPROFILE}/.cache/gdalwmscache if the USERPROFILE configuration option is set.

  • ${CPL_TMPDIR}/gdalwmscache_${USER} if CPL_TMPDIR and USER configuration options are set.

    If CPL_TMPDIR is not set, then TMPDIR is used, or TEMP

    If USER is not set, USERNAME is used if set. If neither USERNAME or USER are set, the md5sum of the filename of the configuration file is used)

  • ./gdalwmscache_{md5sum(filename)} if none of the above mentioned configuration options are set.

Note that if the <Unique> element is set to true (which is its default value), a subdirectory whose name is the md5sum of the filename of the configuration file is appended to the caching directory.

The actual caching directory can be got by querying the CACHE_PATH metadata item on the dataset.

Configuration options

Configuration options can be specified in command-line tools using the syntax --config <NAME>=<VALUE> or using functions such as CPLSetConfigOption() (C) or gdal.config_options (Python). The following configuration options are available:

  • GDAL_MAX_CONNECTIONS=<integer>: (GDAL >= 3.2) Defaults to 2. Set the maximum number of simultaneous connections.

  • GDAL_ENABLE_WMS_CACHE=[YES/NO]: Defaults to YES. Can be set to NO to disable caching of pixel data.

  • GDAL_DEFAULT_WMS_CACHE_PATH=<string>: Sets the WMS/WMTS cache path is the <Cache> element is included in the WMS/WMTS configuration file without a <Path> element.

Examples

警告

The below examples rely on external servers that might go down over time. They are just here to demonstrate how to use the various services.

  • onearth_global_mosaic.xml - Landsat mosaic from a OnEarth WMS server
    gdal_translate -of JPEG -outsize 500 250 onearth_global_mosaic.xml onearth_global_mosaic.jpg

    gdal_translate -of JPEG -projwin -10 55 30 35 -outsize 500 250 onearth_global_mosaic.xml onearth_global_mosaic2.jpg

    Note : this particular server does no longer accept regular WMS queries.

  • metacarta_wmsc.xml - It is possible to configure a WMS Service conforming to a WMS-C cache by specifying a number of overviews and specifying the 'block size' as the tile size of the cache. The following example is a sample set up for a 19-level "Global Profile" WMS-C cache.

  • tileservice_bmng.xml - - TileService, Blue Marble NG (January)
  • tileservice_nysdop2004.xml - TileService, NYSDOP 2004
  • OpenStreetMap TMS Service Example: Connect to OpenStreetMap tile service. Note that this file takes advantage of the tile cache; more information about configuring the tile cache settings is available above. Please also change the <UserAgent>, to avoid the default one being used, and potentially blocked by OSM servers in case a too big usage of it would be seen.
    gdal_translate -of PNG -outsize 512 512 frmt_wms_openstreetmap_tms.xml openstreetmap.png
  • MetaCarta TMS Layer Example, accessing the default MetaCarta TMS layer.
    gdal_translate -of PNG -outsize 512 256 frmt_wms_metacarta_tms.xml metacarta.png

  • BlueMarble Amazon S3 Example accessed with the TMS minidriver.

  • Google Maps accessed with the TMS minidriver.

  • ArcGIS MapServer Tiles accessed with the TMS minidriver.

  • OnEarth Tiled WMS Clementine, daily, and srtm examples.

  • VirtualEarth Aerial Layer accessed with the VirtualEarth minidriver.

  • ArcGIS online sample server layer accessed with the ArcGIS Server REST API minidriver.

  • IIP online sample server layer accessed with the IIP minidriver.

Open syntax

The WMS driver can open :

  • a local service description XML file :

    gdalinfo description_file.xml

  • the content of a description XML file provided as filename :

    gdalinfo "<GDAL_WMS><Service name=\"TiledWMS\"><ServerUrl>https://gibs.earthdata.nasa.gov/twms/epsg4326/best/twms.cgi?</ServerUrl><TiledGroupName>MODIS Terra CorrectedReflectance Bands367 tileset</TiledGroupName></Service></GDAL_WMS>"

  • the base URL of a WMS service, prefixed with WMS: :

    gdalinfo "WMS:http://wms.geobase.ca/wms-bin/cubeserv.cgi"

    A list of subdatasets will be returned, resulting from the parsing of the GetCapabilities request on that server.

    Starting with GDAL 3.10, specifying the -if WMS option to command line utilities accepting it, or WMS as the only value of the papszAllowedDrivers of GDALOpenEx(), also forces the driver to recognize the passed URL, without the WMS: prefix.

  • a pseudo GetMap request, such as the subdataset name returned by the previous syntax :

    gdalinfo "WMS:http://wms.geobase.ca/wms-bin/cubeserv.cgi?SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&LAYERS=DNEC_250K%3AELEVATION%2FELEVATION&SRS=EPSG:42304&BBOX=-3000000,-1500000,6000000,4500000"

  • the base URL of a Tiled WMS service, prefixed with WMS: and with request=GetTileService as GET argument:

    gdalinfo "WMS:https://gibs.earthdata.nasa.gov/twms/epsg4326/best/twms.cgi?request=GetTileService"

    A list of subdatasets will be returned, resulting from the parsing of the GetTileService request on that server.

  • the URL of a REST definition for a ArcGIS MapServer:

    gdalinfo "http://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer?f=json&pretty=true"

  • (GDAL >= 2.1.0) the URL of a IIP image:

    gdalinfo "IIP:http://merovingio.c2rmf.cnrs.fr/fcgi-bin/iipsrv.fcgi?FIF=globe.256x256.tif"

Generation of WMS service description XML file

The WMS service description XML file can be generated manually, or created as the output of the CreateCopy() operation of the WMS driver, only if the source dataset is itself a WMS dataset. Said otherwise, you can use gdal_translate with as source dataset any of the above syntax mentioned in "Open syntax" and as output an XML file. For example:

gdal_translate "http://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer?f=json" wms.xml -of WMS

The generated file will come with default values that you may need to edit.

See Also