Loading WMS Layers
Loading WMS Layers
Once you have successfully filled in your parameters you can select the Connect button to retrieve the capabilities of the selected server. This includes the Image encoding, Layers, Layer Styles and Projections. Since this is a network operation, the speed of the response depends on the quality of your network connection to the WMS server. While downloading data from the WMS server, the download progress is visualized in the left bottom of the WMS Plugin dialog. <P> Your screen should now look a bit like Figure <A HREF="#fig:connection_wms">21</A>, which shows the response provided by the NASA JPL OnEarth WMS server. <P>
<P> Image Encoding
<P> The Image encoding section now lists the formats that are supported by both the client and server. Choose one depending on your image accuracy requirements.
<P> Layers <A NAME="ogc-wms-layers"></A> <P> The Layers section lists the layers available from the selected WMS server. You may notice that some layers are expandible, this means that the layer can be displayed in a choice of image styles.
<P> You can select several layers at once, but only one image style per layer. When several layers are selected, they will be combined at the WMS Server and transmitted to QGIS in one go.
<P> Transparency<A NAME="ogc-wms-transparency"></A> <P> In this version of QGIS, the transparency setting is hard-coded to be always on, where available.
<P> Coordinate Reference System
<P> A Coordinate Reference System (CRS) is the OGC terminology for a QGIS Projection.
<P> Each WMS Layer can be presented in multiple CRSs, depending on the capability of the WMS server. You may notice that the x changes in the Coordinate Reference System (x available) header as you select and deselect layers from the Layers section.
<P> To choose a CRS, select Change... and a screen similar to Figure #fig:projections in Section #label_projstart will appear. The main difference with the WMS version of the screen is that only those CRSs supported by the WMS Server will be shown.