Most satellite imagery has multiple bands, typically containing values within band of the electromagnetic spectrum.
Each cell in a DEM contains only one value representing elevation of earth surface. An example of a single-band raster data set is a digital elevation model (DEM). Generally, two types of raster use in GIS and remote sensing application: a single band, or layer measure of a single characteristic of spatial area and multiple bands raster contains multiple spatially corresponding matrices of cell values representing the same spatial area. Data types are flexible, including discrete and categorical data, such as soil or land-use maps, or continuous data as in digital elevation models, precipitation gradient maps, or pollutant concentration maps, etc. An example of discrete raster data is Land use raster. There are two types of raster data: continuous and discrete. For instance, an image that has a 1 m spatial resolution means that each pixel in the image represents a 1 m x 1 m area. The size of the area on the surface that each pixel covers is known as the spatial resolution of the image. Unlike vector data, a raster data consists of cells or pixels organized into rows and columns as a matrix where each cell contains a value representing geographical feature on the earth.
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