UNIVERSITY EXAMINATIONS: 2011/2012
YEAR 2 EXAMINATION FOR THE BACHELOR OF SCIENCE IN
INFORMATION TECHNOLOGY
BIT 2304 COMPUTER GRAPHICS
DATE: APRIL 2012 TIME: 2 HOURS
INSTRUCTIONS: Answer Question One and Any other Two Questions
QUESTION ONE
a) Define the following graphics-related concepts;
i) Ray tracing (2Marks)
ii) Clipping (2Marks)
iii) Translation vector (2Marks)
b) List any four objects that are defined in the OpenGL toolkit (4Marks)
c) i) Determine how long it would take to load a 24 -bits-per-pixel frame buffer of a resolution of 1280
by 1024 at a transfer rate of 105 seconds (4Marks)
ii) Determine the scan rate in lines per second for each pixel row on a raster system with a
resolution of 1280 x 1024 and a refresh rate of 60 frames/second (4Marks)
d) Explain the differences between a general graphics system designed for a programmer and one
designed for a specific application, such as architectural design. (4Marks)
e) Discuss the usability considerations when building a graphical user interface (8Marks)
QUESTION TWO
a) i) Differentiate between emissive and non-emissive flat panel displays and give an example of
each (4Marks)
ii) An RGB raster system is to be designed using an 8 inch x 10 inch screen with a resolution
of 100 pixels per inch in each direction. Calculate the amount of storage in megabytes needed
for the frame buffer in order to store 6 bits/pixel in the frame buffer (4Marks)
b) Distinguish between additive and subtractive color models (6Marks)
c) i) Define the term ‘aliasing’ as used in graphics displays (2Marks)
ii) Discuss two major types of aliasing (4Marks)
QUESTION THREE
a) Explain the effect of the following standard transformations
i) Rotation (2Marks)
ii) Translation (2Marks)
iii) Scaling (2Marks)
iv) Reflection (2Marks)
b) Using an appropriate graphics programming language, write statements to accomplish the
following;
i) Set the color of a display window to light gray using RGB color (2Marks)
ii) Set the size of rendered points to be 5 pixels wide (1Mark)
iii)Specify a 420 by 620 window in the top left corner of the display (3Marks)
c) General light sources are difficult to work with because we must integrate light coming from all
points on the source. Briefly explain three types of simple light sources that can be modeled in
computer graphics (6Marks)
QUESTION FOUR
a) Consider a simple shear of an object along its x-axis as represented in the diagram below.
Create a four dimensional transformation matrix for the object (4Marks)
b) The LookAt function is only one possible Application Programmer’s Interface (API) for
positioning the camera. Identify 2 other APIs commonly in use (4Marks)
c) i) Using a diagram illustrate the taxonomy of planar projections (4Marks)
ii) Identify two benefits of oblique projections (2Marks)
d) Compare the effects of Goraud shading with Phong shading for a polygon mesh (6Marks)
QUESTION FIVE
a) Computer graphics defines simple geometric objects using three basic types; point, vector and
scalar:
i) Explain each of these basic types from a geometric view (6Marks)
ii) Discuss operations involving these basic types in the vector and affine spaces (6Marks)
b) Write a function named ‘render’ that will draw a single blue polygon with four vertices
of equal length on a window with white background color (8Marks)
