For communication purposes, raster images, which are series of dots in a matrix pattern, provide a superior product than vector images, which are straight lines. Now, depending on the intended audience and the data being mapped, a vector presentation might be adequate. But generally speaking, a raster image, especially an air photo, grabs the user because of recognizable features on the earth, instead of graphic representations in the form of lines. With proper sophistication and computing power, raster data can actually be integrated with vector data to produce a highly effective map. As expected, there is a price.
Raster data requires more storage.
On the positive side, printers and plotters favor the dot pattern over the line pattern in vector data. The problems of fitting an image onto one screen remains, but printouts on quality plotters are clean, clear, and readable. However, surveys do show that GIS users most commonly produce a map on-screen, rather than as a hard copy printout. Although the majority of digital maps are viewed and manipulated on a computer screen, users do need a hard copy printout for publication or other presentation purposes. Just as colors, text, and lines have varying degrees of communicative success on the screen, the printouts possess similar drawbacks.