Different Types of Base Maps in GIS – Graphical Information System

What is a basemap?  The term basemap is see often in GIS and refers to a collection of GIS data and/or orthorectified imagery that form the background setting for a map.  The function of the basemap is to provide background detail necessary to orient the location of the map.  Basemaps also add to the aesthetic appeal of a map.

Typical GIS data and imagery that make up the layers for a basemap: streets, parcels, boundaries (country, county, city boundaries), shaded relief of a digital elevation model, waterways, and aerial or satellite imagery.  Depending on the type of map, any combination of those layers can be used.

For example, for a map showing foreclosed properties, the basemap would consist of GIS data such as streets (with labels) and parcel lines. 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.

Base maps are reference maps. They contain:

1. reference features such as rivers, roads, terrain and settlements;
2. cartographic references such as a coordinate system, north direction and scale.

Types of base maps

1. Topographic maps
2. Radar image maps
3. Aerial photo maps
4. Satellite image maps

1. Topographic maps

• Most common kind of base map
• Topography means shape and elevation of the land
• Topography is shown with contour lines

Contour lines :

Indicate height or elevation of the land above sea level

Pattern of the contour lines show the shape of the land

Note that contour lines:

• are never straight;
• never cross each other;
• always cross rivers.