Data federation addresses the problem of integrating data from heterogeneous source models and includes concepts to map those different source models into the common model at the federated layer.

数据联合处理有关集成来自异类源模型的数据的问题，包括将这些不同的源模型映射到联合层的公共模型的概念。

youdao

Key points include setting the projection of the map file to EPSG: 4326 and defining the WMS layer you want to pull in along with its appropriate metadata (the layer section).

关键的几点是：将地图文件的投影设为EPSG： 4326以及定义想要拉入的wms层及其相应的元数据(LAYER部分)。

youdao

A MapServer map file is created exactly as in Listing 3, but with the LAYER section describing a shapefile instead of a WMS, as Listing 5 illustrates.

结果会如清单3那样创建一个MapServer地图文件，只不过LAYER部分描述的是一个shapefile而不是之前的WMS，如清单5所示。

youdao

So, this approach requires one more layer of effort: converting the height map (or at least its visible tiles) into a "normal map" which is smooth and natural enough to be subjected to lighting effects and then displayed on screen.

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