All About Online Data in Global Mapper

Perhaps the easiest way to begin a new project and load data into Global Mapper is with the Connect to Online Data tool. Accessed from a text button on the home screen, a button in the File toolbar, or an item in the File menu, this powerful component of Global Mapper provides users with the option to stream data from online sources into the current workspace. Streaming data requires an internet connection to load and display, but once streamed into Global Mapper, it can be exported from the program to a supported file format and stored locally for offline use or additional processing. While typically used to stream reference or base map layers from the list of built-in sources, Global Mapper’s Online Data tool can provide much more.

Global Mapper’s Connect to Online Data tool supports raster image data as well as vector feature data. Raster files are streamed into Global Mapper as tiles of pixels that update when zooming and panning to display the appropriate resolution for the screen bounds and scale in Global Mapper. Vector features are first downloaded to a temporary file and are then displayed in Global Mapper. To save any data for future offline use, raster or vector data can be exported to a supported file format.

Built-in Online Sources

After opening the Connect to Online Data tool for the first time in Global Mapper you may be surprised to see a comprehensive list of available sources. While Blue Marble is not a data producer, connection to available data sources is provided to make it easy for users to bring data into the program, even if they have none stored locally. The extensive list of sources is organized into categories describing the topic of the data provided by the source making it intuitive to find data of a specific type to stream into Global Mapper.

Many of the built-in online sources are raster image format data. These image sources are not limited to aerial imagery, and include sources for land cover, aviation and marine navigation charts, street maps, and more. A handful of sources have the ability to stream elevation data into Global Mapper. ASTER and SRTM sources provide lower resolution worldwide terrain data, while newer sources like the United States 3DEP data provide higher resolution elevation grids for a specific area. The built-in online source list also contains several sources offering vector data. Vector online sources are less common than their raster-based counterparts, and these sources are mostly grouped under U.S. Data > State Sources, which cover a more limited area.

Where is the online data from?

While the built-in online sources are predominantly free, the list does include a section of Premium Content containing sources that require a login or key that can be acquired through the organization preparing and hosting the data. All available data, premium or free, accessed through the Connect to Online Data tool is processed and hosted by third-party organizations, as Blue Marble is not a data producer. Metadata, usage restrictions, and additional information for a built-in source can be accessed by right-clicking on the source name and selecting to Display Source Web Page/Terms of Service.

Custom Online Sources

Access to the built-in sources of geospatial data provides a great start, but the Connect to Online Data tool in Global Mapper also provides users with the ability to add additional online sources. Custom online sources added to your installation of Global Mapper can be publicly available services, services produced or maintained by private companies or organizations, or local data exported and stored in a tiled web-format.

Both raster image and vector feature online services can be added to Global Mapper’s list of online sources. The following service types are supported:

• Web Map Service (WMS)
• Tiled Web Map Service (WMTS)
• Tile Map Service (TMS)
• Open Street Map Tiles (OSM)
• Esri RESTful/Google Maps Tiles
• Web Coverage Service (WCS)
• Esri RESTful Feature Service
• Web Feature Service (WFS)

From the Connect to Online Data window in Global Mapper, new sources can be added from an XML definition file with the Add Sources from File button, or manually added from a source URL with the Add New Source button.

Adding a Source from a URL

To add a custom WMS Source from a URL, the Add New Source button is clicked, and the WMS (Web Map Service) format is selected. In the resulting dialog, the Service URL is entered and a request to Get List of Available Data Layers is executed.

The desired layer is selected, in this example the source only has one available layer, and after clicking OK Global Mapper prompts the user to name the source. By default the source inherits the layer name, but this can be edited. The new source can be placed in an existing category, or a new custom category can be added to organize custom online sources. Once added, the source will be available in your installation of Global Mapper and the data can be streamed through the Connect to Online Data tool.

Loading Data from an Online Source

Loading data from an online source can be as simple as selecting the source and clicking Connect, however the bottom half of the dialog box has options to choose the area of data to download as well asr some simple display options.

The area for which data is loaded can be determined by the current screen bounds, a radius around an address or coordinate location, coordinate-defined bounds, or the extent of currently selected polygons. Any of these options are available when selecting to load a source, along with the option to load data for the entire bounds of the source. It is important to remember that the display of streamed data is dependent on an internet connection. Loading the entire area of a worldwide dataset may cause a slowdown in data rendering as you zoom and pan in the data view.

Once data is streamed into and displayed in Global Mapper, the data will appear as a layer in the Control Center and the Layer Options will be available to alter the display of the data. That being said, there are a couple options regarding data display in the Connect to Online Data dialog box. The resampling method can be set while choosing the online source, or it can be altered after loading data through the Layer Options. Another display option that can only be set through the Connect Online Data tool is the Detail Level. This setting impacts the resolution or detail of data displayed in Global Mapper. Selecting to stream data with less detail will result in lower resolution data likely resulting in reduced load and rendering times. Conversely, selecting more detail will stream data at a higher resolution.

If you would like to explore the online sources in Global Mapper download a 14-day free trial today! If you have any questions, don’t hesitate to get in touch. 

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