IPU BCA Semester 5 - Computer Graphics - Raster Scan vs Random Scan System

Raster Scan vs Random Scan System

Computer Graphics

SNo.		Raster Scan System	Random Scan System
1	Resolution	Poor Resolution because picture definition is stored at intensity level.	High resolution because picture definition stored at command level.
2	Electron Beam	Electron beam moves from top to bottom one row at a time.	Electron beam moves to part of screen to be drawn. Also called vector display system.
3	Cost	Less expensive	Costlier as compared to raster scan.
4	Refresh Rate	Usually 60 to 80 frames per second. Refresh rate is independent of picture complexity.	Depends on no. of lines to be drawn i.e. 30 to 60 times per second. Refresh rate depends directly on picture complexity.
5	Picture Definition	Stores picture details in Frame buffer	Stores details as separate vector commands in refresh display file.
6	Line Drawing	Zig Zag lines are displayed since plotted values are discrete.	Smooth lines drawn as line drawing follows mathematical functions.
7	Realism in Display	Gives realistic display scenes because shading and hidden surface techniques.	Does not give realistic scenes.
8	Image Drawing	Uses pixels as scan lines to display image.	Uses mathematical functions to draw.
9	Interlacing	Uses interlacing	Doesn't use interlacing
10	Editing	Editing is difficult since one need to manipulate frame buffer.	Editing is easy since picture details are commands.