# BIT2301A  BAC3206  COMPUTER GRAPHICSa. KCA Past Paper

UNIVERSITY EXAMINATIONS: 2016/2017
EXAMINATION FOR THE DEGREES OF BACHELOR OF SCIENCE IN
INFORMATION TECHNOLOGY/ APPLIED COMPUTING
BIT2301A BAC3206 COMPUTER GRAPHICS
FULLTIME/ PART TIME
ORDINARY EXAMINATIONS
DATE: AUGUST, 2017 TIME: 2 HOURS
INSTRUCTIONS: Answer Question One & ANY OTHER TWO questions.

QUESTION ONE [30 MARKS]
a) Describe THREE basic elements of computer graphics (4 Marks)
b) Real-world objects can be displayed on the screen in two ways. Explain. (4 Marks)
c) Explain the following rendering terms:
i) Ray casting
ii) Ambient light
iii) Mesh (6 Marks)
d) Discuss any THREE key applications of computer-aided design (6 Marks)
e) Draw the graphics rendering pipeline and explain each stage of this pipeline (6 Marks)
f) Write statements with an appropriate graphics language to perform the following:
i) Configure ambient lighting (2 Marks)
ii) Initialize a display window of 700 x 500 pixels (2 Marks)
QUESTION TWO [20 MARKS]
a) Explain the concept of rasterization as it is used in computer graphics (1 Mark)
b) Using the DDA algorithm, find the intermediate points that can be drawn between the
endpoints (2,1) and (8,6) to generate a line. Show your calculations. (5 Marks)
c) Distinguish between the X-shear and Y-shear and use appropriate diagrams to illustrate each
of these (4 Marks)
d) Explain in detail the following procedures for hidden surface elimination:
i) Object precision (5 Marks)
ii) Image precision (5 Marks)
QUESTION THREE [20 MARKS]
a) Explain the effect of the following standard transformations
i) Rotation (2 Marks)
ii) Translation (2 Marks)
iii) Scaling (2 Marks)
iv) Reflection (2 Marks)
b) Consider a triangle of vertices (2, 3) (5, 5) (6,2) that has been rotated 90 counterclockwise.
i) Calculate the new vertices of the triangle. Show your calculations (6 Marks)
ii) Draw the original and rotated triangle on the Cartesian plane (3 Marks)
c) Explain the Painter’s algorithm for drawing objects (3 Marks)
QUESTION FOUR [20 MARKS]
a) Explain the concept and relevance of clipping (2 Marks)
b) Identify any FOUR properties that a graphics model might contain (4 Marks)
c) Distinguish between the following terms:
i) Window and viewport
ii) Zooming and panning (4 Marks)
d) The Cohen-Sutherland line clipping algorithm divides the viewport into regions defined by
viewport edges and assign each region a 4-bit outcode. Draw a diagram to illustrate these
regions and explain how each of the outcodes is derived. (4 Marks)
e) Define the following terms and use a diagram to illustrate each term
i) Global illumination
ii) Local illumination (6 Marks)
QUESTION FIVE [20 MARKS]
a) Explain how flat shading is done and when it is appropriate to use flat shading
(3 Marks)
b) Discuss THREE advantages and THREE limitations of z-buffering (6 Marks)
c) Describe the following basic sources of light:
i) Point light
ii) Spotlight
iii) Directional light (6 Marks)
d) Explain in detail how light affects the appearance of objects (5 Marks)

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