Easier access to scientific data
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Voice of the Ocean ERDDAP™
Easier access to scientific data |
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is an Open Geospatial Consortium (OGC)
and ISO (19128)
standard for "the
creation and display of registered and superimposed map-like views of information that come
simultaneously from multiple remote and heterogeneous sources."
See the list of datasets available via WMS at this ERDDAP installation.
and
uDig
.
To make these work, you would install the software on your computer.
Then, you would enter the URL of the WMS service into the client.
For example, in ArcGIS (not yet fully working because it doesn't handle time!), use
"Arc Catalog : Add Service : Arc Catalog Servers Folder : GIS Servers : Add WMS Server".
In ERDDAP, each dataset has its own WMS service, which is located at
In practice, we haven't found any WMS clients that properly handle dimensions
other than longitude and latitude (e.g., time), a feature which is specified by the WMS
specification and which is utilized by most datasets in ERDDAP's WMS servers.
You may find that using a dataset's Make A Graph
form and selecting the .kml file type
(an OGC standard) to load images into Google Earth
provides a good (non-WMS) map client.
See the list of datasets with Make A Graph at this ERDDAP installation.
, which is a very versatile WMS client, for the WMS page for each ERDDAP dataset (like this).
See the list of datasets available via WMS at this ERDDAP installation.
Leaflet doesn't automatically deal with dimensions other than longitude and latitude
(e.g., time), so you will have to write JavaScript (or other scripting code) to do that.
(Adventurous JavaScript programmers can look at the Source Code from a web page like this.)
Another commonly used JavaScript WMS client is
OpenLayers
.
In practice, it is easier, more versatile,
and more efficient to use a dataset's Make A Graph web page
than to use WMS for this purpose.
See the list of datasets with Make A Graph at this ERDDAP installation.
The supported parameters for a GetCapabilities request are:
| name=value* | Description |
|---|---|
| service=WMS | Required. |
| version=version | Currently, ERDDAP's WMS supports "1.1.0", "1.1.1", and "1.3.0".
This parameter is optional. The default is "1.3.0". |
| request=GetCapabilities | Required. |
:
all characters in query values other than A-Za-z0-9_-!.~'()* must be encoded as %HH, where
HH is the 2 digit hexadecimal value of the character, for example, space becomes %20.
Characters above #127 must be converted to UTF-8 bytes, then each UTF-8 byte must be percent encoded
(ask a programmer for help). There are
"websites that percent encode/decode for you
.
| name=value* | Description |
|---|---|
| service=WMS | Required. |
| version=version | Request version. Currently, ERDDAP's WMS supports "1.1.0", "1.1.1", and "1.3.0". Required. |
| request=GetMap | Request name. Required. |
| layers=layer_list | Comma-separated list of one or more map layers.
Layers are drawn in the order they occur in the list.
Currently in ERDDAP's WMS, the layer names from datasets are named datasetID
: variableName .
In ERDDAP's WMS, there are five layers not based on ERDDAP datasets:
|
| styles=style_list | Comma-separated list of one rendering style per requested layer. Currently in ERDDAP's WMS, the only style offered for each layer is the default style, which is specified via "" (nothing). For example, if you request 3 layers, you can use "styles=,,". Or, even easier, you can request the default style for all layers via "styles=". Required. |
| 1.1.0: srs=namespace:identifier
1.1.1: srs=namespace:identifier 1.3.0: crs=namespace:identifier |
Coordinate reference system.
Currently in ERDDAP's WMS 1.1.0, the only valid SRS is EPSG:4326. Currently in ERDDAP's WMS 1.1.1, the only valid SRS is EPSG:4326. Currently in ERDDAP's WMS 1.3.0, the only valid CRS's are CRS:84 and EPSG:4326, Required. |
| bbox=4commaSeparatedValues | Bounding box corners in SRS/CRS units. For version=1.3.0 with CRS=EPSG:4326, the 4 values are: minLat,minLon,maxLat,maxLon. For all other situations, the 4 values are: minLon,minLat,maxLon,maxLat. (The reverse order! Yes, it's bizarre. Welcome to the world of OGC!) ERDDAP supports requests within the dataset's longitude (perhaps 0 to 360, perhaps -180 to 180) and latitude range. Most WMS clients assume longitude values are in the range -180 to 180. If ERDDAP offers a variant of a dataset with longitude -180 to 180, use it for WMS requests. Required. |
| width=output_width | Width in pixels of map picture. Required. |
| height=output_height | Height in pixels of map picture. Required. |
| format=output_format | Output format of map. Currently in ERDDAP's WMS, only image/png is valid. Required. |
| transparent=TRUE|FALSE | Background transparency of map. Optional (default=FALSE). If TRUE, any part of the image using the BGColor will be made transparent. |
| bgcolor=color_value | Hexadecimal 0xRRGGBB color value for the background color. Optional (default=0xFFFFFF, white). If transparent=true, we recommend bgcolor=0x808080 (gray), since white is in some color palettes. |
| exceptions=exception_format | The format for WMS exception responses. Optional.
Currently, ERDDAP's WMS 1.1.0 and 1.1.1 supports "application/vnd.ogc.se_xml" (the default), "application/vnd.ogc.se_blank" (a blank image) and "application/vnd.ogc.se_inimage" (the error in an image). Currently, ERDDAP's WMS 1.3.0 supports "XML" (the default), "BLANK" (a blank image), and "INIMAGE" (the error in an image). |
| time=time | Time value of layer desired, specified in ISO 8601 format: yyyy-MM-ddTHH:mm:ssZ .
Currently in ERDDAP's WMS, you can only specify one time value per request.
In ERDDAP's WMS, the value nearest to the value you specify (if between min and max) will be used. In ERDDAP's WMS, the default value is the last value in the dataset's 1D time array. In ERDDAP's WMS, "current" is interpreted as the last available time (recent or not). Optional (in ERDDAP's WMS, the default is the last value, whether it is recent or not). |
| elevation=elevation | Elevation of layer desired.
Currently in ERDDAP's WMS, you can only specify one elevation value per request.
In ERDDAP's WMS, this is used for the altitude or depth (converted to altitude) dimension (if any). (in meters, positive=up) In ERDDAP's WMS, the value nearest to the value you specify (if between min and max) will be used. Optional (in ERDDAP's WMS, the default value is the last value in the dataset's 1D altitude or depth array). |
| dim_name=value | Value of other dimensions as appropriate.
Currently in ERDDAP's WMS, you can only specify one value per dimension per request.
In ERDDAP's WMS, this is used for the non-time, non-altitude, non-depth dimensions. The name of a dimension will be "dim_" plus the dataset's name for the dimension, for example "dim_model". In ERDDAP's WMS, the value nearest to the value you specify (if between min and max) will be used. Optional (in ERDDAP's WMS, the default value is the last value in the dimension's 1D array). |
:
all characters in query values other than A-Za-z0-9_-!.~'()* must be encoded as %HH, where
HH is the 2 digit hexadecimal value of the character, for example, space becomes %20.
Characters above #127 must be converted to UTF-8 bytes, then each UTF-8 byte must be percent encoded
(ask a programmer for help). There are
websites that percent encode/decode for you
.
(Revised from Table 8 of the WMS 1.3.0 specification)
ERDDAP is compatible with the current WMS 1.3.0 standard.
ERDDAP is also compatible with the older WMS 1.1.1 standard, which may be needed when working with older client software.
ERDDAP is also compatible with the older WMS 1.1.0 standard, which may be needed when working with older client software.