Difference between Raster Scan and Random Scan

Nov 22, 2011 by

Difference between Raster Scan and Random Scan

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  1. daniel

    Random scan and raster scan are display systems based on CRT monitors. They are all used for exhibiting or projecting softcopy data using eight graphic or alphanumeric forms. The information displayed using both techniques is said to be temporary. Raster scan offers lesser memory cost in contrast with random scan. Discover the differences between random scan and raster scan here below.

    1. Technology used

    Raster scan, which is based on the normal TV technology, utilizes one electron beam. This beam is swept through the screen, creating a pattern that comprises of large illuminated spots. Meanwhile, random scan does not involve sweeping the whole screen using the electronic beam. Instead, this beam is only directed to areas of a screen in which the image is supposed to be created. Random scan therefore creates the vector display, which is essentially an oscilloscope that is controlled by the computer.

    2. Analogies

    In layman terms, these two displays can be explained using a simple action of utilizing a pen for drawing an image on a paper. The first method to use would require lifting and then lowering the pencil onto the paper. As you have seen, this procedure is very tedious and this is the random scan. The other method is drawing several parallel lines throughout the screen. This makes drawing vertical and horizontal lines simpler and this is what is referred to as a raster scan.

    Nevertheless, both display systems are not being used nowadays since newer methods of producing individual pixels have been developed. These new methods are independently used for both absorbing and emitting light. However, it is hard to attain realism when using random scan. In contrast, higher realism levels can be attained when using raster scan. This is achieved through using hidden surface method and advanced shading.

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