M. James Kang Liang Guo 8715: Spatial Databases Encyclopedia Article: E2 Summary of Key Sources Key Terms: Raster Image and Vector Image Peck, Wendy. "Graphic Underworld: Vector vs. Raster." August 5, 2000. <http:// www.webreference.com/graphics/column31/2.html> o This article gives a general overview and tutorial on the main differences between Vector and Raster Images. o In general, the main differences between these two types of image formats is that in Raster images, its made up of pixels identifying a single color and in Vector images, it uses mathematical containers such as a line or a polygon. There are several advantages and disadvantages between the two image formats. In Raster images, the disadvantage is that since its made up of pixels, it does not scale very well. This is because as you expand the image, the image becomes pixilated and the illusion of the smoothing affect within the pixels is lost. However, in Vector images, each color component is broken into shapes which can be defined using some mathematical structure. Thus, the image remains to be very crisp when the image is scaled. Vector images are very useful for graphics or logos, but these types of images do not work well for photographs. Since there are a lot of variations between the colors, numerous containers need to be created which increases the file size. Raster images are frequently used for photographs, since a pixilated image can show the smoothness of the photograph and use a smaller file size than a Vector Image. "The Basics of Raster Imagery." alabamamaps.ua.edu. University of Alabama. <http://alabamamaps.ua.edu/tutorial/raster.html> This o site gives a brief tutorial between Raster and Vector imagery. The difference in this tutorial versus the one before is that they use Alabama maps to show the distinction and usefulness between the two image formats. "Raster Image Files." Scv.bu.edu. Boston University. <http://scv.bu.edu/SCV/Tutorials/ImageFiles/image101.html> o This site gives a further detailed overview on how a Raster image is created and the various file formats offered for Raster images. Rai, Sumita, "ArcGIS Extensions." University of Pittsburgh. <http://visc.sis.pitt.edu/tutorials/GIS/SpatialAnalyst.pdf> o This presentation explains how the concepts of Vector and Raster images are applied to GIS applications. It gives a general overview of how these types of images are created for maps. S. Fotheringham, C. Brunsdon, M. Charlton. "Quantitative Geography: Perspectives on Spatial Data Analysis." SAGE Publications, May 1 2000.
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