I am working on visualizing year-on-year data in a map. This data needs to be shown on the map, show what year the data was recorded in, and convey the frequency/total amount of records at a specific point.
Initially I planned to show this using a simple 2D map, with different colored icons for each year, and using a number label to show the total count at a specific point, but the problem/challenge I encountered was how to convey multiple points at the same location that were different years.
My other idea was to instead use a 3D map, and stack visual markers on the map colored based on the year the data was recorded in. This has the benefit of showing what locations are more popular in a more visual way, and being able to show recordings at the same location with different years, but it still does not feel like the best solution:
If the points overlap but are not the same position, you can get this weird stacking effect like you see in the bottom left. This may also become slow to load for larger datasets (up to 10,000 records could be shown on the map at a time).
Any ideas, suggestions, or examples of how to show year-on-year data on a map that clearly conveys frequency, the year it was recorded, and is a good experience for the end user, would be much appreciated.