THEORY EXAMINATION (SEM–IV) 2016-17 COMPUTER GRAPHICS

Subject: Computer Graphics (NCS403)

Exam Type: Theory
Semester: IV (4th Semester)
Duration: 3 Hours
Maximum Marks: 100

Section A — Short Questions (10 × 2 = 20 Marks)

These are basic conceptual and definition-based questions testing core knowledge of computer graphics.

Topics covered:

Purpose and working of a video controller       DDA algorithm — tracing a line from (0,0) to (-6, -6)

Definition of refresh buffer       Transformation matrix for rotation about an arbitrary point in space

Proof of commutative property of successive rotations     Function of shear transformation

Properties of B-spline curves               Difference between specular reflection and diffuse reflection

Difference between viewport and window      Explanation and examples of aliasing and antialiasing

Section B — Descriptive / Numerical Questions (5 × 10 = 50 Marks)

These are analytical and calculation-based questions involving algorithms and geometry.

Key questions:

Bresenham’s Line Drawing Algorithm: Derivation and comparison with DDA.

Display parameter problem: Calculation of             Pixel aspect ratio

Frame buffer size                                                     Data transfer rate (KB/sec)

Window-to-Viewport transformation: Mapping coordinates with accurate diagrams.

Hidden surface removal algorithms: Scan-line vs. Depth buffer technique.

Cohen–Sutherland line clipping algorithm — step-by-step explanation.

Explanation of quadratic and polygonal surfaces.

Description of Warn model (lighting or shading model)

Section C — Long Analytical / Derivation Questions (2 × 15 = 30 Marks)

Transformation Composition:
Given figures A(-2,0), B(0,-2), C(-2,-4), D(-4,-2) transformed to A'(1,-1), B'(3,3), C'(6,3), D'(4,-1) using a composite transform (T₂ × H₁ × S₁ × R₁ × T₁).

Write all transformation matrices                  Reduce to a single scale, rotation, and translation matrix

Area Subdivision Algorithm:

Explanation with suitable diagram             Advantages and disadvantages

Visible Surface Detection Methods:

Detailed discussion on all visibility determination algorithms used in 3D rendering

Major Topics Covered

Line drawing algorithms (DDA, Bresenham)

2D and 3D geometric transformations (rotation, scaling, translation, shearing)

Window-to-viewport mapping                            Hidden surface removal

Surface modeling (quadratic, polygonal)             Shading models (specular, diffuse, Warn)

Line clipping (Cohen–Sutherland)                        Area subdivision and visible surface detection

Purpose of the Paper

This exam checks both theoretical and practical understanding of 2D/3D graphics, including transformation algorithms, rendering concepts, and visualization principles.

Students must be comfortable with matrices, coordinate geometry, and algorithms for drawing, clipping, and transforming objects on a computer screen.