What Is a Bse Map?
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:
- reference features such as rivers, roads, terrain and settlements;
- cartographic references such as a coordinate system, north direction and scale.
Types of base maps
- Topographic maps
- Radar image maps
- Aerial photo maps
- 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.