| | 1 | = The Web Map Service file format = |
| | 2 | ''Accessing several different types of web image services is possible using the WMS format in GDAL. Services are accessed by creating a local service description XML file.'' |
| | 3 | |
| | 4 | ''The official GDAL documentation for the WMS file format is http://www.gdal.org/frmt_wms.html.'' |
| | 5 | |
| | 6 | == Introduction == |
| | 7 | Given a particular WMS server, it should always be possible to query its capabilities through the GetCapabilities request. From this information it is possible to build a reasonable service description XML file for GDAL. In particular, the following relevant data is usually discernible: |
| | 8 | |
| | 9 | * server URL and version (<ServiceURL> and <Version> tags); |
| | 10 | * image projection (<SRS>, <CRS>, <Projection> tags); |
| | 11 | * image extent (<UpperLeftX>, <UpperLeftY>, <LowerRightX>, <LowerRightY> tags); |
| | 12 | * available layers (<Layers> tag); |
| | 13 | * available styles (<Styles> tag) |
| | 14 | |
| | 15 | What is missing is the image size in pixels (<SizeX> and <SizeY> tags) and, since it is a mandatory parameter, it should be found somewhere else or... 'guessed'. |
| | 16 | |
| | 17 | In the following, there are some examples of complete service description XML files ready to be used with GDAL, using different WMS mini-drivers. This list is meant to extend the examples given in the official documentation at http://www.gdal.org/frmt_wms.html |
| | 18 | |
| | 19 | == TerraServer-USA (US) == |
| | 20 | The main website is http://terraservice.net/ and the web services are described at http://terraservice.net/webservices.aspx |
| | 21 | |
| | 22 | The capabilities url is http://terraservice.net/ogccapabilities.ashx?version=1.1.1&request=getcapabilities&service=wms |
| | 23 | |
| | 24 | All maps can be reprojected on the fly to EPSG:4326, but the image size in pixels is easily derivable only for the single UTM zones: 2m/pixel,EPSG:26904 - EPSG:26919, i.e. NAD83 / UTM Zone 4N-19N. So, instead of a single XML file, we need a specific file for each zone. |
| | 25 | |
| | 26 | In the following the files for accessing the DRG layer (USGS Raster Graphics Topo Maps) with default style: |
| | 27 | * EPSG:26904 NAD83 / UTM Zone 4N |
| | 28 | * EPSG:26905 NAD83 / UTM Zone 5N |
| | 29 | * EPSG:26910 NAD83 / UTM Zone 10N |
| | 30 | * EPSG:26911 NAD83 / UTM Zone 11N |
| | 31 | * EPSG:26912 NAD83 / UTM Zone 12N |
| | 32 | * EPSG:26913 NAD83 / UTM Zone 13 |
| | 33 | * EPSG:26914 NAD83 / UTM Zone 14N |
| | 34 | * EPSG:26915 NAD83 / UTM Zone 15N |
| | 35 | * EPSG:26916 NAD83 / UTM Zone 16N |
| | 36 | * EPSG:26917 NAD83 / UTM Zone 17N |
| | 37 | * EPSG:26918 NAD83 / UTM Zone 18N |
| | 38 | * EPSG:26919 NAD83 / UTM Zone 19N |
| | 39 | |
| | 40 | |
| | 41 | == Portale Cartografico Nazionale (Italy) == |
| | 42 | |
| | 43 | == Blue Marble: Next Generation (global, monthly images) == |
