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Raster files generally are used to store image information, such as scanned paper maps or aerial photographs. They are also used for data captured by satellite and other airborne imaging systems. Images from these systems are often referred to as remote-sensing data. Unlike other raster files, which express resolution in terms of cell size and dots per inch (dpi), resolution in remotely sensed images is expressed in meters, which indicates the size of the ground area covered by each cell.

Some common raster formats are described below:

Arc Digitized Raster Graphics (ADRG) - ADRG is a format used by the US military to store raster images of paper maps.

Band Interleaved by Line (BIL),. 

Band Interleaved by Pixel (BIP), and Band Sequential (BSQ) -  BIL, BIP, and BSQ are formats produced by remote-sensing systems. The primary difference among them is the technique used to store brightness values captured simultaneously in each of several colors or spectral bands.

Digital Elevation Model (DEM) - DEM is a raster format used by the USGS to record elevation information. Unlike other raster file formats, DEM cells do not represent color brightness values, but rather the elevations of points on the earth’s surface.

PC Paintbrush Exchange (PCX) - PCX is a common raster format produced by most scanners and personal computer (PC) drawing programs.

Spatial Data Transfer Standard (SDTS) - As was indicated under vector formats above, SDTS is a general-purpose format designed to transfer geographic information. One SDTS variant is the raster profile, designed as a standard format for transferring raster data. However, this protocol has not as yet been finalized.

Tagged Image File Format (TIFF) - Like PCX, TIFF is a common raster format produced by PC drawing programs and scanners. 

     

Any digital map is capable of storing much more information than a paper map of the same area, but it’s generally not clear at first glance just what sort of information the map includes. For example, more information is usually available in a digital map than what you see on-screen. And evaluating a given data set simply by looking at the screen can be difficult: What part of the image is contained in the data and what part is created by the GIS program’s interpretation of the data? You must understand the types of data in your map so you can use it appropriately.

Three general types of information can be included in digital maps:

• Geographic information,which provides the position and shapes of specific geographic features.

• Attribute information,which provides additional non-graphic information about each feature.

• Display information,which describes how the features will appear on the screen.

Some digital maps do not contain all three types of information. For example, raster maps usually do not include attribute information, and many vector data sources do not include display information.