WCS services
The Open Geospatial Consortium, Inc. (OGC), Web Coverage Service (WCS) provides an open specification for sharing raster datasets on the Web. ArcGIS Server allows you to publish WCS services from imagery collections, maps, or geodatabases that contain rasters.
A WCS service returns data in a format that can be used as input for analysis and modeling. This is in contrast with OGC WMS services, which only return a picture of the data. The raster datasets made available through WCS services are referred to as coverages. These should not be confused with the vector datasets available in previous versions of ArcGIS, which were also called coverages.
You can do three things with a WCS service:
- GetCapabilities--Returns service-level metadata and a brief description of the data collection
- DescribeCoverage--Returns a full description of one or more coverages
- GetCoverage--Returns a coverage in a well-known coverage format
To learn more about WCS services, see http://www.opengeospatial.org/standards/wcs.
Creating a WCS service
In ArcGIS Server, WCS is exposed as a capability of a map service, an image service, or a geodata service. To create a WCS service, you need to create one of these three services and enable the WCS capability. As WCS service is used for serving raster data, so the sources for WCS services should be one of these:
- A map containing raster layers or mosaic layers
- A raster dataset or a mosaic dataset
- A layer file referencing a raster dataset or a mosaic dataset
- A geodatabase that contains raster data
To be published as WCS coverage, the source raster data must have a valid spatial reference.
- To enable the WCS capability for a map service, use ArcMap to create the map document containing the raster layers you want to serve. When doing so, keep in mind that only the raster data in the map will be served in a WCS service; the layer properties will not be maintained, and any feature data will be excluded from the WCS service. When you've saved your map document, use either Manager or ArcCatalog to publish it as a map service. The service can then be consumed by any client that supports the OGC WCS specification.
- To enable the WCS capability for an image service, prepare the raster dataset, mosaic dataset, or layer file referencing a raster dataset or mosaic dataset that you want to publish, then publish it as an image service with the WCS capability enabled, using either ArcCatalog or ArcGIS Server Manager.
- To enable the WCS capability for a geodata service, create a geodatabase (file, personal, or ArcSDE geodatabase), load the raster data you want to serve into the geodatabase, then publish the geodatabase as a geodata service with the WCS capability enabled using either ArcCatalog or ArcGIS Server Manager.
A WCS service created from map server or geodata server may contain multiple coverages as one map document can contain multiple layers referencing raster data, and so is geodata server. A WCS service from an image service contains single WCS coverage.
After you publish the service, you can set further properties for the WCS service on the Capabilities tab of the Service Properties dialog box. If you want more flexibility over how the service advertises its capabilities, you can use external capabilities files.
Learn more about using external capabilities files with WCS services
For example, WCS services created with ArcGIS Server only support their native spatial reference system and WGS84. Given that ArcGIS Server supports thousands of predefined spatial reference systems, these spatial reference systems can be added to a WCS service and advertised to WCS clients by using external WCS capabilities files.
The WCS versions supported by ArcGIS Server are 1.0.0, 1.1.0, and 1.1.1.
Special characters
The following characters cannot be included in any of the service properties: &, <, >, ", '. If you need to use one of these characters, you must substitute the appropriate escape sequence from the table below:
|
& |
& |
|
< |
< |
|
> |
> |
|
" |
" |
|
' |
' |
Securing WCS services
A WCS service exposes an ArcGIS Server map, geodata, or image service to WCS consumers. The security for a WCS service is managed by controlling the security of its parent map, geodata, or image service. If a particular role, for example, Planners, is denied access to a map, then Planners will not be able to access the map no matter whether they try to consume it through SOAP, representational state transfer (REST), or WCS interfaces.
ArcGIS Server supports a number of different authentication schemes. Services that are expected to be accessed via OGC interfaces should be secured using HTTP Basic, HTTP Digest, or Integrated Windows Authentication. Most OGC clients (both non-ESRI and ESRI clients) will understand and work with these widespread standard authentication schemes.
Connecting to the WCS service
To connect to a WCS service, you need to know the URL. When you use ArcGIS Server to publish a WCS service, its URL takes this format:
http://<server name>/<instance name>/services/<folder name (if applicable)>/<service name>/<service type (can be MapServer, ImageServer, or GeoDataServer)>/WCSServer?
For example, if you had a folder Japan that contained the map service Tokyo running on a machine myServer with the default instance name arcgis, the URL of your WCS service would look like this:
http://myServer/arcgis/services/Japan/Tokyo/MapServer/WCSServer?
If you had an image service IdahoImages running on myServer with the instance name of PublicLands, your URL for the WCS service would look like this:
http://myServer/PublicLands/services/IdahoImages/ImageServer/WCSServer?
Supported output formats
Supported output formats for WCS services are GeoTIFF, NITF, HDF, JPEG, JPEG2000, and PNG. To learn more about how these image formats are supported in ArcGIS, see Technical specifications for raster dataset formats in the ArcGIS Desktop Help.
Types of clients for WCS services
A web browser is the simplest client of a WCS service. WCS requests can be issued through HTTP, and the responses or exceptions are returned through the browser. WCS services support three operations: GetCapabilities, DescribeCoverage, and GetCoverage. Through URL parameters, a client can use these operations to obtain service metadata, coverage information, and coverages from the WCS service. These operations and parameters are detailed in the OGC WCS specification.
ArcGIS Desktop can act as a client for WCS services. A WCS coverage can be displayed in ArcMap (similar to a raster layer), exported to a raster dataset using the Export Data dialog box, and consumed by geoprocessing tools that take a raster layer as input. To learn more, see Adding a WCS service to ArcMap.
Additionally, many third-party applications are available for working with WCS and other OGC services.
Below are examples of requests to ArcGIS Server WCS services using a web browser.
GetCapabilities
This request will return all service-level metadata and a brief description of the data in GML format. To use the GetCapabilities operation, copy and paste the WCS service URL into the address bar and add ?SERVICE=WCS&VERSION=1.0.0&REQUEST=GETCAPABILITIES to the end of the URL.
DescribeCoverage
This request will return a full description of one or more coverages within the service in GML format. To use the DescribeCoverage operation, copy and paste the WCS service URL into the address bar and add ?SERVICE=WCS&VERSION=1.0.0&REQUEST=DescribeCoverage&COVERAGE=1 to the end of the URL.
GetCoverage
This request will return a coverage in one of the supported formats: GeoTIFF, NITF, HDF, JPEG, JPEG2000, and PNG. To use the GetCoverage operation, copy and paste the WCS service URL into the address bar and add ?SERVICE=WCS&VERSION=1.0.0&REQUEST=GetCoverage&COVERAGE=1&CRS=EPSG:4326&RESPONSE_CRS=EPSG:4326&BBOX=-158.203125,-105.46875,158.203125,105.46875&WIDTH=500&HEIGHT=500&FORMAT=jpeg to the end of the URL.
For WCS services originating from mosaic datasets, TIME and IMAGES parameters can be added:
Time
TIME—Supports time queries by specifying a time instance or time range. The format can be YYYYMMDDHHMMSS, YYYYMMDD, YYYYMM, or YYYY.
TIME=1999 (time at year 1999)
URL example: http://server_name/arcgis/services/service_name/ImageServer/WCSServer?SERVICE=WCS&VERSION=1.0.0&REQUEST=GetCoverage&COVERAGE=1&FORMAT=GeoTIFF&BBOX=-180,-55.5,180,83.5&WIDTH=720&HEIGHT=278&CRS=EPSG:4326&INTERPOLATION=nearest%20neighbor&Band=1,2,3&TIME=1999
TIME=1980/2010 (time from year 1980 to 2010)
URL example: http://server_name/arcgis/services/service_name/ImageServer/WCSServer?SERVICE=WCS&VERSION=1.0.0&REQUEST=GetCoverage&COVERAGE=1&FORMAT=GeoTIFF&BBOX=-180,-55.5,180,83.5&WIDTH=720&HEIGHT=278&CRS=EPSG:4326&INTERPOLATION=nearest%20neighbor&Band=1,2,3&TIME=1980/2010
TIME=1999-12-31T14:30:30/2000-01-01T14:30:30
URL example: http://server_name/arcgis/services/service_name/ImageServer/WCSServer?SERVICE=WCS&VERSION=1.0.0&REQUEST=GetCoverage&COVERAGE=1&FORMAT=GeoTIFF&BBOX=-180,-55.5,180,83.5&WIDTH=720&HEIGHT=278&CRS=EPSG:4326&INTERPOLATION=nearest%20neighbor&Band=1,2,3&TIME=1999-12-31T14:30:30/2000-01-01T14:30:30
Images
IMAGES—Supports query of individual rasters
IMAGES=1,2 (where the numbers are the object IDs of the image service catalog table)