How are projections handled for WMS requests?

Cartographica is intelligent about making WMS requests in order to optimize for best quality viewing.

As with all Cartographica maps, the display section of any Cartographica window is in the Map Projection (CRS).   Most often, this is the CRS of the first layer that you imported, unless you have set it using the Map > Project Map... command.

When you add a WMS layer to an existing document, Cartographica attempts to match its request to the server with the current Map Projection.   After inquiring of the WMS Server which CRS are available, it attempts to find a match.   If a match is found, then future requests are made using that CRS, resulting in a quick and low-distortion view.

If the map's CRS/Projection is not available from the WMS Server for the layers requested, Cartographica will request the data in a known format that is served by the WMS server and then warps that format to the Map Projection.   The default projection can be set by using the Layer > Set Layer's Projection… command, but it is a requirement that the projection be available for that particular layer or it may show up blank.

Generally speaking, Cartographica will try (and succeed) in doing the right thing when it makes the selection automatically.

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