Besides using the dynamic graphic layer background map, you can embed data provided by map services as static backgrounds. Unlike the background map, the downloaded data is saved to the hard drive, so that it is available without a permanent Internet connection (with the exception of Bing Maps).
Map providers offer maps and aerial photos in a pre-arranged tile configuration. They come in a graphic format (e.g. JPEG or PNG) and in a uniform size that allows for several detail levels. The data is available in a projected form, usually in Mercator projection (Coordinate systems). Visum automatically downloads the tiles for the current network section (in the detail level selected) from the map provider, converts the data into the coordinate system format used in Visum and integrates the data as background objects. Depending on the size of the current network section, the original tiles are combined to several large files. The background files generated are saved to special background folders in the project directory. The folder structure is shown in the Administration tab, in the Background window. You can use the administration function to control the visibility of network backgrounds (Using Visum: Showing and hiding backgrounds).
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Note: To use background images of map providers, you need to set a coordinate system for your network (Using Visum: Selecting a coordinate system). Background images of freely accessible map providers are downloaded once and saved to the computer. The embedded maps are not automatically updated or adapted to a different network section. This is why the use of freely available map data does not require a continuous Internet connection. If you want to update background images, delete the existing ones and embed new ones. |
