History of Interactive Computer Graphics

Historical Context of Computer Graphics

• Ivan Sutherland is recognized as the grandfather of interactive computer graphics, notably for his work with Sketchpad, demonstrating early possibilities in graphics.
• The 1960s saw the development of influential systems alongside Sutherland’s work, including SAGE and Sketchpad.
• The first computer game, Spacewar, was developed in 1961 on the PDP-1 platform, marking a significant stride in gaming history.
• IBM created the first Computer Aided Design (CAD) system in 1964, enhancing engineers' ability to create mechanical drawings and conduct tests without physical prototypes.

Development Phases of Computer Graphics

• The gestational period was followed by a childhood period lasting 6-7 years, characterized by the consolidation of earlier ideas and further development from the gestational phase.
• The adolescent period, primarily in the 1970s to early 1980s, introduced the first commercial microprocessor, the Intel 4004, revolutionizing computer design and making computations more affordable.
• Advancements during the adolescent period led to the development of realistic 3D graphics and applications in entertainment and filmmaking, increasing interest and investment in the field.

Graphic Systems and Devices

• Two primary types of graphic systems based on pixel excitation methods: vector scan devices and raster scan devices.

Vector Scan Devices

• Also known as random scan stroke writing or calligraphic devices, these utilize continuous geometric primitives like lines and curves to represent images.
• Only the pixels associated with the geometric shapes are excited, requiring high precision and complex hardware, leading to higher costs.
• Vector scan is effective for rendering wireframe images, but can struggle with complex scenes, resulting in visible flicker.

Raster Scan Devices

• In raster scan devices, the entire pixel grid is used to represent images, allowing for the excitation of all pixels rather than just selected ones.
• The scanning process typically moves from left to right and top to bottom, ensuring that each pixel is considered for excitation.
• The video memory in raster systems is known as the frame buffer, with a size equal to the screen resolution.

Display Processing Dynamics

• Display processors operate at very high speeds (nanosecond scale), while video controllers are slower (millisecond scale) due to mechanical arrangements.
• The disparity in speed necessitates efficient resource utilization for image manipulation in interactive settings.

Image Rendering Pipeline

• Objects are defined and go through subsequent pipeline stages for image rendering.
• The first stage involves modeling transformation, where the reference frames for defining objects are established.
• Each object is defined in its local coordinate system, and when combined to create scenes, they are placed in a new reference frame called the world coordinate system.

Conclusion

• The evolution of computer graphics through various phases and device technologies has shaped its current capabilities, enabling complex rendering and interactive graphics applications.