Line Drawing Display - Random Scan Display Device

The display through this system is termed as Line Drawing Display. The sequence controls the subsequent stages, demonstrated in following figure.

• Graphics Commands
• Display-File Translator
• Display-File Program
• Display (File) Processor
• VDU

Figure: Block Diagram of Line Drawing Display

The method is quite related to the way a plotter or a person draws a line segment, the pen being moved beside a specific direction for a specific length then changing direction or lifting the pen and moving to a newest point.

For illustration, the image of a hut shown in following figure of Vector Scan Display; would be traced as five line segments, the right and left roof slopes, the right and left walls and the floor line. Effectiveness is achieved through minimizing wasted motion as would occur if a line segment starts at a point different from the end point of the previous segment equivalent to picking up the pen and putting that down at the other point to draw the subsequent segment. Hence, this would be better to trace the hut like ABCDE, quite than as CB, CD, BA, DE, and AE, like a draftsman might draw.

Figure: Vector Scan Display