Define random scan system.

Introduction

A random scan system, also known as a vector display, stroke-writing display, or calligraphic display, is a computer graphics rendering method. This system is primarily used in applications where high-quality line art and animations are required. It is different from the conventional raster scan system (used in televisions and modern computer displays), as it draws each line independently, which can be in any order, hence the term 'random'.

Detailed Explanation of Random Scan System

In a random scan system, the electron beam is directed only to the parts of the screen where a picture is to be drawn. The system draws and refreshes one line at a time in any specified order, not in a raster order. This is why it's called a 'random' scan system.

The process of drawing a picture on the screen using a random scan system involves the following steps:

1. The picture is first defined in terms of straight line segments.
2. Each line segment is then specified separately in the system memory.
3. The system cycles through each line segment, drawing one after another.

The refresh rate in a random scan system is dependent on the complexity of the picture. The formula used to calculate the refresh rate is:

Refresh rate = Number of lines / (Time to draw one line * Number of frames per second)

Comparison between Random Scan System and Raster Scan System

Examples of Random Scan System

Early computer graphics systems, such as the IBM 2250 and Tektronix 4014, used random scan systems. These systems were capable of producing high-quality line art and animations, which were essential for applications such as CAD (Computer-Aided Design) and scientific visualization.

Program to Simulate Random Scan System

Here is a simple Python program to simulate the working of a random scan system:

class LineSegment:
    def __init__(self, start_point, end_point):
        self.start_point = start_point
        self.end_point = end_point

class RandomScanSystem:
    def __init__(self):
        self.line_segments = []

    def add_line_segment(self, start_point, end_point):
        self.line_segments.append(LineSegment(start_point, end_point))

    def draw(self):
        for line_segment in self.line_segments:
            print(f'Drawing line from {line_segment.start_point} to {line_segment.end_point}')

random_scan_system = RandomScanSystem()
random_scan_system.add_line_segment((0, 0), (1, 1))
random_scan_system.add_line_segment((1, 1), (2, 2))
random_scan_system.draw()

In this program, we first define a LineSegment class to represent a line segment. We then define a RandomScanSystem class, which maintains a list of line segments to be drawn. The add_line_segment method is used to add a line segment to the system, and the draw method is used to draw all the line segments in the order they were added.

Conclusion

In conclusion, a random scan system is a computer graphics rendering method that draws and refreshes one line at a time in any order. It is primarily used in applications where high-quality line art and animations are required. Despite its limitations, such as a refresh rate dependent on the complexity of the picture, it remains an important part of the history of computer graphics.

Note: A diagram is not necessary for this answer.

Summary

A random scan system, also known as a vector display, stroke-writing display, or calligraphic display, is a computer graphics rendering method. It draws and refreshes one line at a time in any order, allowing for high-quality line art and animations. This is different from the conventional raster scan system used in televisions and modern computer displays.

Analogy

A random scan system is like an artist drawing a picture on a canvas. Instead of filling in each pixel one by one, the artist draws each line independently, in any order, resulting in a high-quality artwork.