Combining several geographic data sources for a single visualization in a Power BI map can be done in the following ways:
Organize Your Data: Ensure that all geographic data sources are consistently cleaned and formatted. This implies aligning column names such as "Latitude," "Longitude," or "Region Name," ensuring there are no duplicate values or even missing ones, and aligning data types.
Upload Data to Power BI: Bring your data sources into Power BI with the "Get Data" function. After importation, you would have to build relationships between tables if your geographic data exists across several datasets.
Create a Unified Table: Use Power Query to merge or append the datasets if required. For example, one table has latitudes and longitudes, while another has region names. Join them based on a common key like "Location ID."
Map Visual Configuration: Add a map visual to your Power BI canvas, then drag and drop the relevant fields into the visual's settings.
Put "Latitude" and "Longitude" into the right fields for accurate plotting.
Add "Region Name" to "Location" if you want regions to be highlighted or labeled.
Add a measure or category field in the 'Size' or 'Legend' section to add depth or categorize the data points.
Improve and test the map: Fine-tune your map using zoom levels, along with clustering or heat mapping, to show the coverage and density of your data. Then, validate the plotted points and regional boundaries.
This offers a seamless combining of different geographic data into a single and sharing insight.