UNIT-I: Introduction
The Advantages of Interactive Graphics, Representative Uses of Computer Graphics, Classification of
Application Development of Hardware and software for computer Graphics, Conceptual Framework for Interactive
Graphics, Overview, Scan: Converting Lines, Scan Converting Circles, Scan Converting Ellipses.
UNIT-II: Hardcopy & Display Technologies
Hardcopy Technologies, Display Technologies, Raster-Scan Display System, Video Controller, Random-Scan
Display processor, Input Devices for Operator Interaction, Image Scanners, Working exposure on graphics
tools like Dream Weaver, 3D Effects, etc. Clipping: Southland-Cohen Algorithm, Cyrus-Beck Algorithm,
Midpoint Subdivision Algorithm.
UNIT-III: Geometrical Transformation
2D Transformation, Homogeneous Coordinates and Matrix Representation of 2D Transformations, composition of
2D Transformations, the Window-to-Viewport Transformations, Introduction to 3D Transformations Matrix.
UNIT-IV: Representing Curves & Surfaces
Polygon meshes, parametric Cubic Curves, Quadric Surface; Solid Modeling: Representing Solids, Regularized
Boolean Set Operation, Primitive Instancing, Sweep Representations, Boundary Representations, Spatial
Partitioning Representations, Constructive Solid Geometry, Comparison of Representations.
UNIT-V: Introductory Concepts
Multimedia Definition, CD-ROM and the multimedia highway, Computer Animation (Design, types of animation,
using different functions), Uses of Multimedia, Introduction to making multimedia – The stage of Project,
hardware & software requirements to make good multimedia, skills and Training opportunities in Multimedia,
Motivation for Multimedia usage.
UNIT-I: Introduction to Computer Graphics & Multimedia Application
1. The Advantages of Interactive Graphics
- Improves user engagement and experience
- Useful for simulations, games, and design software
- Enables real-time feedback and interaction
- Helpful in data visualization and modeling
2. Representative Uses of Computer Graphics
- CAD (Computer-Aided Design) for engineering and architecture
- Medical Imaging (e.g., MRI, CT scans)
- Virtual Reality and Augmented Reality
- Scientific visualization and simulations
- Entertainment (video games, movies, animations)
3. Classification of Applications
- Interactive Graphics: Drawing tools, games, CAD systems
- Non-Interactive Graphics: Reports, image rendering, scientific diagrams
4. Development of Hardware and Software
- Hardware: Monitors, graphic cards, plotters, digitizers
- Software: Graphic libraries (OpenGL, DirectX), drivers, rendering engines
5. Conceptual Framework for Interactive Graphics
This includes the stages of interaction:
- User input (mouse, keyboard)
- Application processing (e.g., rotation, zoom)
- Output generation (display on screen)
6. Overview of Scan Conversion
Scan conversion is the process of converting geometric primitives (lines, circles, ellipses) into pixels
for raster displays.
7. Scan Converting Lines
Lines are approximated by plotting intermediate points on a pixel grid.
Example: Bresenham’s Line Algorithm
Input: (x1, y1) and (x2, y2)
Step: Choose the nearest pixel to the theoretical line
Output: Set of pixels forming a line
Diagram:
• → plotted pixel
(x1, y1) ●———●———●———●———(x2, y2)
↑ ↑ ↑ ↑
Pixels chosen based on error term
8. Scan Converting Circles
Used to draw circular shapes using symmetry and efficient algorithms.
Example: Midpoint Circle Algorithm
Input: Radius r and center (xc, yc)
Use 8-way symmetry to reduce computation
Diagram:
Plot one-eighth and mirror it:
●●●
● ●
● ●
● ●
●●●
9. Scan Converting Ellipses
Uses midpoint algorithm with two regions for x and y dominance.
Input: rx, ry (x and y radii), center (xc, yc)
Apply symmetry in all four quadrants
Diagram:
Ellipse (symmetrical on x and y axes):
●●●●
● ●
● ●
● ●
●●●●
UNIT-II: Computer Graphics Technologies and Clipping Algorithms
1. Hardcopy Technologies
Hardcopy devices convert digital graphics into physical output:
- Printers: Inkjet, Laser, Dot Matrix
- Plotters: Used for engineering drawings and large vector graphics
- Film Recorders: Used in multimedia and motion picture production
2. Display Technologies
Types of display devices:
- CRT (Cathode Ray Tube)
- LCD (Liquid Crystal Display)
- LED (Light Emitting Diode)
- OLED (Organic LED)
3. Raster-Scan Display System
Raster-scan systems draw graphics by illuminating pixels row-wise (scanlines).
Diagram:
Scanlines: →→→→
Pixels: [●●●●●●●]
Each pixel is addressed individually and refreshed regularly
4. Video Controller
It acts as the interface between display hardware and the CPU. It:
- Reads pixel values from the frame buffer
- Generates the signal to drive the monitor
- Synchronizes display timing
5. Random-Scan Display Processor
Also known as vector displays, they draw graphics using commands rather than pixels.
- Uses electron beam to draw directly on screen
- Efficient for line drawings and CAD
6. Input Devices for Operator Interaction
- Keyboard
- Mouse
- Joystick
- Light Pen
- Graphics Tablet
7. Image Scanners
Convert printed images or documents into digital form.
- Flatbed scanners
- Handheld scanners
- Drum scanners
8. Working Exposure on Graphics Tools
- Dreamweaver: Visual editor for web design (HTML, CSS)
- 3D Effects: Tools like Blender or Adobe After Effects for modeling and animation
9. Clipping
Clipping is the process of cutting parts of graphics that lie outside a defined region (viewport).
Southland-Cohen Algorithm
Efficient line clipping algorithm for rectangular clipping window using region codes.
Steps:
1. Assign region codes to endpoints
2. Use bitwise AND to test visibility
3. Recursively clip lines outside region
Diagram:
Region Codes: 1000 | 1001 | 1010
0000 | LINE | 0000
0100 | 0101 | 0110
Cyrus-Beck Algorithm
Used for clipping lines against convex polygonal windows.
Uses parametric line equation:
P(t) = P0 + t(P1 - P0), where 0 ≤ t ≤ 1
Calculates entering and exiting values of t
Diagram:
Convex polygon → line intersects → compute t-in and t-out
Midpoint Subdivision Algorithm
Recursively divides the line into halves and checks which part lies within the window.
1. Test if line segment is completely inside/outside
2. If partially inside, divide at midpoint
3. Repeat until clipped completely or fully outside
Diagram:
Initial Line → Midpoint → Divide → Test each part recursively
UNIT-II: Output Devices, Clipping Algorithms & Graphics Tools
1. Hardcopy Technologies
- Devices that produce a permanent output on physical media.
- Examples: Printers (Inkjet, Laser), Plotters.
- Used for blueprints, CAD drawings, printed images, etc.
2. Display Technologies
- CRT (Cathode Ray Tube)
- LCD (Liquid Crystal Display)
- LED (Light Emitting Diode)
- OLED, Plasma, Touch screens
3. Raster-Scan Display System
Displays the image as a matrix of pixels in a raster format.
Process:
→ Beam scans pixel row-by-row (left to right, top to bottom)
→ Frame buffer stores pixel color values
Diagram:
Scan direction:
→
●●●●●●●●●●
→
●●●●●●●●●●
→
●●●●●●●●●●
4. Video Controller
- Controls refresh operations and access to the frame buffer
- Synchronizes scanning beam and pixel data
5. Random-Scan Display Processor
Also called vector display; draws lines directly between points.
- Used in oscilloscopes and early graphics systems
- Efficient for wireframe models
6. Input Devices for Operator Interaction
- Keyboard, Mouse, Trackball, Light pen
- Touchscreens, Joysticks, Graphics Tablets
7. Image Scanners
- Convert physical images/documents into digital format
- Flatbed, Handheld, Drum scanners
8. Graphics Tools Exposure
- Dreamweaver: Web design tool with visual interface
- 3D Effects Tools: Blender, Autodesk Maya, After Effects
- Use Cases: Animation, modeling, VFX, interface design
9. Clipping Algorithms
Used to cut portions of graphics that fall outside a defined region (viewport).
Southland-Cohen Algorithm
Step-by-step:
1. Assign region codes to endpoints
2. Use bitwise operations to check visibility
3. If partially visible, clip against viewport boundaries
Diagram (region codes):
100 | 101 | 001
-----+-----+-----
100 | 000 | 001
-----+-----+-----
110 | 011 | 010
Cyrus-Beck Algorithm
- Parametric line-clipping for convex polygon clipping window
- Uses dot product to determine entering and leaving points
P(t) = P1 + t(P2 - P1), where 0 ≤ t ≤ 1
Midpoint Subdivision Algorithm
- Divide the line segment into two halves recursively
- Check for visibility at each midpoint
- Efficient for recursive clipping implementation
UNIT-II: Hardcopy Technologies, Display Technologies, and Algorithms
1. Hardcopy Technologies
- Printers: Inkjet, Laser, Dot-matrix
- Plotters: Used for producing large drawings, such as blueprints
- 3D Printers: For physical object creation from 3D models
2. Display Technologies
- CRT (Cathode Ray Tube): Traditional display used in older monitors and televisions
- LCD (Liquid Crystal Display): Modern display technology used in most flat-screen
monitors
- LED (Light Emitting Diode): A more efficient and high-quality display type
- OLED (Organic LED): Offers superior contrast and color quality
3. Raster-Scan Display System
A raster-scan display system generates images by lighting up pixels in a grid pattern.
- Function: Pixels are lit in sequence to form images, such as in CRT and LCD
monitors
- Drawbacks: Limited by pixel resolution and requires fast refresh rates for smooth
images
Example: A simple raster-scan display will start at the top-left corner and sweep
across each row, lighting up pixels as it moves.
4. Video Controller
The video controller processes image data and converts it into signals to drive the display hardware.
- Function: Responsible for video timing, controlling color, and resolution.
- Components: RAMDAC (RAM Digital-to-Analog Converter), video memory
5. Random-Scan Display Processor
Random-scan displays (also known as vector displays) render images directly using lines and geometric
shapes.
- Function: Draws objects line by line, without scanning each pixel
- Use: Best for applications like CAD, where sharp and clear lines are important
6. Input Devices for Operator Interaction
- Mouse: Pointing and clicking device
- Keyboard: Used for textual input
- Touchscreen: Input through touch (common in modern devices)
- Stylus: Used for precise input on tablets and digital drawing boards
- Trackpad: Input through finger gestures
7. Image Scanners
Devices that convert physical images into digital formats.
- Flatbed Scanners: Used for scanning images, documents, and photos
- Handheld Scanners: Portable devices that scan images directly
8. Working Exposure on Graphics Tools
Familiarization with graphics software tools used for creating, editing, and rendering images.
- Dreamweaver: A web design and development tool used for HTML, CSS, and JavaScript
editing
- 3D Effects: Tools like Blender or Autodesk Maya used for 3D modeling, animation,
and rendering
9. Clipping Algorithms
Clipping is the process of trimming the objects to fit within a specified region.
- Southland-Cohen Algorithm: A line-clipping algorithm used for clipping a line to a
rectangular viewport.
- Cyrus-Beck Algorithm: A parametric line-clipping algorithm that is more efficient
for arbitrary polygons.
- Midpoint Subdivision Algorithm: An algorithm used for clipping lines to fit within
specific regions.