What Problem Does This Solve?
Users need a geographical reference to understand and relate to the information displayed on top of it.
When to Use This Pattern
Using a basemap is advisable in almost all the maps because they provide the background detail necessary to orient the location and reference the overlaid operational data. They often include a geodetic control network as part of its structure.
What’s the Solution?
Show landforms, roads, transportation, waterbodies, landmarks, political boundaries, or shaded relief of a digital elevation model underneath the operational data like thematic information, points of interest, parcels, etc. Depending on the type of map and the operational data the basemap needs to be adjusted, simplified, or optimized across all scales. A map showing hiking trails would benefit from a basemap containing a digital elevation model or topo lines that shows elevation, thus allow viewers to understand the rise and fall of a trail’s path.
Why Use This Pattern?
Basemaps help users to orient themselves with both location and scale. A well designed basemap supports and highlights the data displayed on top. Basemaps often define the projection that all the other layers need to be displayed in. They also add to the aesthetic appeal of a map and are therefore a crucial visual element of any application design.
- Carefully select the level of detail to show at each scale.
- Style the basemap per well-established cartographic rules and with the target user in mind, i.e. think how the user using the application perceives the places they are looking at.
- Allow users to toggle between alternate basemaps (see Basemap Toggle) to temporarily view data through a different ‘lens’
- Custom basemaps:
- Different projections and tiling schemes
- More appropriate regional/cultural context
- Richer detail