What is a Basemap?

Gökçe Bal
Oct 7
3 min read

Maps are like the scenes of a story, but the setting that sets the stage is actually the basemap . The basemap is the background map layer upon which other data layers are placed. This layer helps us understand where we are and provides visual context. As defined by Esri's GIS glossary, the basemap is "the foundation layer of a map's visual and geographic context." In other words, it serves as a solid foundation upon which information like streets, terrain, or infrastructure data sits. In short, a map without a basemap is practically incomplete.

Technology and Benefits

Basemap Types

Every map conveys a message. Choosing the appropriate basemap type is critical to conveying the right message. Different types of basemaps are preferred depending on the location, scale, and purpose. Here are the most common types:

Orthophoto Base Map

Orthophoto maps, produced from satellite or aerial images, provide a detailed view of the Earth from above. Features such as buildings, roads, and parks are shown at true scale. Their high resolution makes them ideal for distance measurement and terrain analysis. For example, the satellite layer in Google Maps is of this type.

Topographic Base Map

Topographic maps reveal the elevation data and natural features of a region. Mountains, valleys, and rivers are depicted as curved lines. They may also include man-made features such as administrative boundaries, roads, and parks. Examples of this group include topographic maps from the United States Geological Survey (USGS) or the 1:25,000 scale topographic maps produced by the General Directorate of Mapping in Turkey. They are indispensable for urban planners and outdoor enthusiasts.

Satellite Base Map

It consists of wide-area imagery taken from space by satellites . Regular updates provide up-to-date information. It is frequently used for post-disaster damage assessment or large-scale land use analyses. Sentinel-2 and Landsat satellites are well-known examples of this type.

Elevation (DEM) Base Map

A Digital Elevation Model (DEM) displays digital elevation values of the land surface. The elevation of each point above sea level is represented by numbers. Such maps are used for cost calculations or flood risk analyses in infrastructure projects. NASA's SRTM data and LiDAR measurements are frequently used in DEM production.

Contour Base Map

These maps, which display contour lines, visualize changes in terrain's slope and elevation. As the lines converge, the slope increases; as they diverge, they represent a flatter area. They are used in a variety of fields, from hiking trail planning to construction projects.

Advantages of Using Basemap

Basemaps form the basis of many applications in today's technologies:

Location-Based Services: Navigation apps display points around users using a basemap. Google Maps and Apple Maps are the most well-known examples.
Disaster Management: After an earthquake, flood or fire, up-to-date satellite maps provide rapid information to rescue teams.
Urban Planning: Accurate planning is done using topographic and elevation maps for new roads, infrastructure and construction projects.
Agriculture and Environmental Monitoring: The health of agricultural areas, forest cover or water resources are monitored with satellite-based basemaps.
As you can see, basemaps put complex geographic data into an understandable framework and form the backbone of modern mapping technologies.