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Computer Graphics Question Paper

Computer Graphics

Course:Bachelor Of Science In Information Technology

Institution: Kca University question papers

Exam Year:2009

UNIVERSITY EXAMINATIONS: 2008/2009
SECOND YEAR EXAMINATION FOR THE DEGREE OF BACHELOR OF
SCIENCE IN INFORMATION TECHNOLOGY
BIT 2304: COMPUTER GRAPHICS
DATE: AUGUST 2009 TIME: 2 HOURS
INSTRUCTIONS: Answer question ONE and any other TWO questions
QUESTION ONE (30 MARKS)
a) Computer graphics systems have played a key role in the advancement of various sectors in the
modern society. Identify FOUR key sectors that have benefited significantly from
advancements in this discipline. (4 Marks)
b) Consider two raster systems with resolutions of 640 by 480 and 2560 by 2048.
(i) Determine the number of pixels that should be accessed per second if the display
controller refreshes the screen at a rate of 120 Hz. (4 Marks)
(ii) Determine the access time per pixel for each of the two systems (2 Marks)
(iii) Determine the minimum difference in storage capacity (per second) between the two
systems, if each pixel is defined using 8 bits. Give your solution in kilobytes.
(2 Marks)
c) (i) Highlight the key difference between a Random Scan display and a Raster Scan Display.
(4 Marks)
(ii) Elaborate on the use of the following two terms with reference to graphical systems:
- Graphics API (1 Mark)
- Toolkit (1 Mark)
(iii) Identify the key difference between the two-dimensional and three-dimensional viewing
pipelines. (2 Marks)
d) Define the following terms used in computer graphics:
2
(i) Primitive (1 Mark)
(ii) Attribute (1 Mark)
(iii) Pixmap (1 Mark)
e) A GLUT initialization function may contain the following request statement:
glutInitDisplayMode (GLUT_SINGLE |GLUT_RGB|GLUT_DEPTH):
(i) Why is this function referred to as a ‘request’ function? (2 Marks)
(ii) Describe the parameters being initialized in the function. (3 Marks)
(iii) Suggest an alternative entry to the parameter GLUT_SINGLE. What will this new
entry represent? (2 Marks)
QUESTION TWO [20 MARKS]
a) The following paragraph is an extract from an OpenGL program developed in C++
void init(void)
{
GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 1.0 };
GLfloat mat_shininess[] = { 50.0 };
GLfloat light_position[] = { 1.0, 1.0, 1.0, 0.0 };
glClearColor (0.1, 0.1, 0.1, 0.0);
glShadeModel (GL_SMOOTH);
glMaterialfv(GL_FRONT, GL_AMBIENT, mat_specular);
glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);
glLightfv(GL_LIGHT0, GL_POSITION, light_position);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_DEPTH_TEST);
glColorMaterial(GL_FRONT, GL_DIFFUSE);
glEnable(GL_COLOR_MATERIAL);
}
3
(i) Identify and cite four tasks of the display processor contained in the extract
(4 Marks)
(ii) Describe the four parameters being addressed in the statements GLfloat
mat_specular [ ] and GLfloat light_position [ ]. (2 Marks)
(iii) Explain the purpose of each of the three parameters addressed by the statement:
glMaterialfv( ) (3 Marks)
(iv) Describe the three surface lighting effects contained in this extract. (6 Marks)
(v) Which statement would you use to nullify the lighting effects generated above?
(1 Mark)
b) Describe the two algorithms used in surface detection (4 Marks)
QUESTION THREE [20 MARKS]
a) Given a rotational matrix R, a translational matrix A and a coordinate matrix P, show the two
ways to multiply the matrices in order to generate the matrix P’’’, which is a translation
followed by a rotation, then a second translation. (4 Marks)
b) (i) Describe two non-algebraic curves that may be used to generate irregular surfaces
(4 Marks)
(ii) Describe the following types of surfaces used to generate graphical images:
- Regular surfaces (2 Marks)
- Cubic surfaces (2 Marks)
(iii) Describe the CSG solid representation technique. (2 Marks)
c) Distinguish between boundary representation and space-partitioning representation as they
apply in object modeling. (4 Marks)
d) What is the function of the alpha value in a given glClearColor routine? (2 Marks)
QUESTION FOUR [20 MARKS]
a) Polygon planes may be described by the equation:
Ax + By + Cz + D = 0
(i) What do the parameters x, y, and z stand for? (1 Mark)
(ii) What do the parameters A, B, C and D represent? (1 Mark)
(iii) A rectangular plane has the following four vertices: (-3, 3, 2), (0, 3, 2), (0, 0, 2) and
(-3, 0, 2). This plane undergoes a positive 90 degrees rotation about the Y-axis. Use
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a sketch to determine the coordinates of the new plane, calculate the normal vector
and work out the equation of this plane. (10 Marks)
b) Polygon tables are often used to define sets of polygon surface facets on a scene. Use a sketch
to describe the various entries into such a table. (6 Marks)
c) Identify the OpenGL routines that can be used to create a rectangle. (2 Marks)
QUESTION FIVE [20 MARKS]
a) (i) During the generation of a raster image, Aliasing is often witnessed. Explain this
Aliasing phenomenon. (2 Marks)
(ii) Describe the various techniques that may be used to overcome the Aliasing effect
(6 Marks)
b) Using illustrations or inequality relationships, show the meaning of the following terms:
(i) Point clipping (2 Marks)
(ii) Straight Line clipping (2 Marks)
c) Describe the following two projection techniques:
(i) Perspective projection (2 Marks)
(ii) Parallel projection (2 Marks)
d) Explain the purpose of the following procedures in 3-dimensional drawing:
(i) Depth Cueing (2 Marks)
(ii) Exploded views (2 Marks)
Relevant relationships:
A = y1(z2 - z3) + y2(z3 - z1) + y3(z1 - z2)
B = z1(x2 - x3) + z2(x3 - x1) + z3(x1 - x2)
C = x1(y2 - y3) + x2(y3 - y1) + x3(y1 - y2)
D = -x1(z3y2 – z2y3) - x2(z1y3 – z3y1) - x3(z2y1 – z1y2)
N = (V2-V1) x (V3-V1)
Vector product: V1 x V2 = ((V1yV2z-V1zV2y), (V1zV2x-V1xV2z), (V1xV2y – V1yV2x)) T
y = m(xi + 1) + b
pi = 2?yxi – 2?xyi + 2?y + ?x(2b – 1)
p0 = 2?y - ?x

Computer Graphics Question Paper

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