The WMS‐Qs are Web Map Services following the standard defined by the OGC which are aware that some of its layers describe quality parameters of certain variables. Thus, instead of each layer corresponding to one variable like in regular WMS, in WMS‐Q some layers are just statistical descriptors that inform about the quality and ensemble describe one variable.
These instances are connected to the DAB‐Q from where the portal is able to gather them. Each server is presented in the DAB as a metadata record for the services plus a number of metadata records corresponding to each of its served datasets (each dataset is compound of different variables which at same time are described by different quality components). The DAB‐Q does not generate a record for each uncertainty component but just for the dataset level layers.
WMS‐Q conventions are described in the OGC Public Engineering Report 12‐160r1 “OWS 9 Data Quality and Web Mapping Engineering Report” but some problems and details were found in the implementation phase and a new version of this ER was released by GeoViQua. Details on the identification of pixel level layers and how the description of these layers can be converted into ISO metadata descriptions in the DAB can be seen in the Extra deliverable WMS‐Q version 2.0 that will be included as an attachment to the second project report and also included in the GeoViQua website.
It is worth to note that WMS‐Q also recommends the use of MetadataURL as a way to expose the dataset level metadata. This way a WMS service can act as a small metadata catalogue for providers that do not want to expose their catalogue.
Same exercise has been done for Web Map Tile Services (WMTS) creating the WMTS‐Q convention.
WMS‐Q Server Facade for Greenland
The WMS‐Q Server Facade is implemented as a development help for the WMS‐Q Web Client Greenland developed within the project GeoViQua. It allows annotating the capabilities document of any WMS server with keywords according to the WMS‐Q specification, effectively telling a user/client software which layer contains which information, for example data values, standard deviation, or variance.
The server facade is intended for testing and development. Therefore it did not undergo testing of stability or any user studies and should be seen as software in an "alpha" state.
More information here:
WMS-Q service from CREAF
UREAD WMS-Q service
CREAF WMS-Q client