Rasters are well suited for representing data that changes continuously across a landscape (surface). Below is a raster used as a basemap for road data. Three main sources of raster basemaps are orthophotos from aerial photography, satellite imagery, and scanned maps. For example, orthophotographs displayed underneath other layers provide the map user with confidence that map layers are spatially aligned and represent real objects, as well as additional information. Within a GIS, the uses of raster data fall under four main categories:Ī common use of raster data in a GIS is as a background display for other feature layers. While the structure of raster data is simple, it is exceptionally useful for a wide range of applications. Learn more about thematic and continuous data Picture rasters are often used as attributes in tables-they can be displayed with your geographic data and are used to convey additional information about map features. Thematic and continuous rasters may be displayed as data layers along with other geographic data on your map but are often used as the source data for spatial analysis with the ArcGIS Spatial Analyst extension. Pictures include scanned maps or drawings and building photographs.Continuous data represents phenomena such as temperature, elevation, or spectral data such as satellite images and aerial photographs.Thematic data (also known as discrete) represents features such as land-use or soils data.

Rasters are digital aerial photographs, imagery from satellites, digital pictures, or even scanned maps.ĭata stored in a raster format represents real-world phenomena: In its simplest form, a raster consists of a matrix of cells (or pixels) organized into rows and columns (or a grid) where each cell contains a value representing information, such as temperature.

Raster map