Computer Graphics Lecture 1

Introduction to Computer Graphics

• Computer graphics is concerned with producing pictures or images using a computer.
• The field began 50 years ago with the display of a few lines on a cathode ray tube (CRT).
• Today, we can generate images by computer that are indistinguishable from photographs of real objects.

Applications of Computer Graphics

• The applications of computer graphics can be divided into four major areas:
• Display of Information
• Design
• Simulation and Animation
• User Interfaces

Display of Information

• Scientific visualization provides graphical tools to help researchers interpret vast quantities of data.
• Images generated by converting data to geometric entities have yielded new insights into complex processes.

Design

• Computer-aided design (CAD) pervades fields such as architecture, mechanical parts, and VLSI circuits.
• Design is an iterative process, using interactive graphical tools to generate possible designs, test them, and explore other solutions.

Simulation and Animation

• Graphics systems are used as simulators, such as flight simulators, which increase safety and reduce training expenses.
• Arcade games have also evolved to be as sophisticated as flight simulators.

User Interface

• Our interaction with computers has become dominated by a visual paradigm, including windows, icons, menus, and pointing devices.
• Graphical network browsers, such as Firefox, Chrome, and Safari, use these same interface tools.

Graphic System

• A computer graphic system consists of:
• Input devices
• Central Processing Unit (CPU)
• Graphics Processing Unit (GPU)
• Memory
• Frame buffer
• Output devices

Frame Buffer

• The frame buffer stores the image we see on the output device as an array of pixels.
• The depth of the frame buffer determines the number of colors that can be represented.

Pixels

• Pixels can be either on or off (1-bit bitmap) or represent varying shades of color (using more bits).

CPU and GPU

• In a simple system, the CPU does both normal processing and graphical processing.
• The graphical function of the processor is to assign values to the pixels in the frame buffer.

Output Devices

• The dominant type of display was the cathode-ray tube (CRT), but has been replaced by newer technologies.

Input Devices

• Most graphics systems provide a keyboard and at least one other input device, such as:
• Mouse
• Joystick
• Data tablet
• Trackball

Images: Physical and Synthetic

• We want to create realistic images of computer-generated three-dimensional objects.
• This involves image formation, including lighting, shading, and material properties.

Objects and Viewers

• Two basic entities are part of any image formation process: Objects and Viewers.
• Objects are formed by specifying the positions of geometric primitives, such as points, lines, and polygons.
• The viewer forms an image of the objects.

Light and Images

• Light is necessary for objects to be visible.
• We must indicate how color enters the picture or what the effects of surface properties are.

Camera System

• The pinhole camera is a simple imaging system that helps us understand the functioning of cameras and other optical imagers.

Camera Specifications

• Camera specifications include:
• Position
• Orientation
• Focal length
• Film plane

Human Visual System

• The human visual system is a complex imaging system with components similar to a camera or microscope.
• Light enters the eye through the lens and cornea.
• The lens forms an image on the retina at the back of the eye.
• Rods and cones on the retina are light sensors and determine the resolution of our visual systems.