Code: DC-09                                                                          Subject: COMPUTER GRAPHICS

Time: 3 Hours                                                         June 2006                                             Max. Marks: 100

NOTE: There are 9 Questions in all.

· Question 1 is compulsory and carries 20 marks. Answer to Q. 1. must be written in the space provided for it in the answer book supplied and nowhere else.

· Out of the remaining EIGHT Questions answer any FIVE Questions. Each question carries 16 marks.

· Any required data not explicitly given, may be suitably assumed and stated.

Q.1       Choose the correct or best alternative in the following:                                         (2x10)

a. Which of the following software packages is used for engineering and architectural systems?

(A)  UNIX                                          (B)  CAD

(C)   CAL                                           (D)  NS2

b. A major component of a GUI is

(A) Window manager                         (B)  Mouse

(C)  Joystick                                        (D)  Input-output device

             c.   Refresh rate on a random access device depends on

(A)  The architecture of the system.    

(B)  The colour of the CRT.

(C)  The number of lines to be displayed. 

(D)  The size of the monitor.

             d.   Which of the following is not rigid body transformation?

(A)  Rotation                                      (B)  Translation

(C)  Reflection                                    (D)  Shearing        

             e.   The transformation matrix  represents reflection about the line

(A) x = 0                                            (B)  y = 0

(C)  y = x                                            (D)  y = -x

             f.    Homogenous co-ordinates for the point (2, 3) is

(A) (4, 6, 2)                                       (B)  (4, 6, 1)

(C)  (6, 4, 2)                                       (D)  (6, 4, 1)

g.   MIDI is a standard for

(A) video conferencing.                     

(B) connecting electronic instruments to computers.

(C) compression of audio.                 

(D) Animation.

             h.   In Cohn-Sutherland algorithm there are out codes based on the nine region.  The out code of a point in top-left region is,

(A) 0001.                                           (B) 0101.

(C) 0000.                                            (D) 1101.

             i.    Which of the following representations of solids use set operations?

(A) Quadtree.                                     (B) Sweep method.

(C) CSG.                                            (D) BSP.

             j.    Intensity attenuation function can be defined as, (d is the distance that light has travelled)

(A)  (B)   Min

(C)  Max (D)

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

Q.2     a.   Describe the construction and working of liquid crystal display.                           (7)

             b.   What do you mean be simulation?  How is it used in animation?                          (5)

             c.   Describe the principal of interlacing.                                                                    (4)

Q.3     a.   What is an image scanner?  Describe its working.                                               (8)

             b.   Write DDA algorithm for a line with slope more than 1.                                       (4)

c.   What do you mean by output primitives?                                                            (2)

d.   Define the term viewport.                                                                                   (2)

Q.4     a.   What are the co-ordinates of a square with vertices (0, 0), (2, 0) (0, 2) and (2, 2), when it is transformed into a shifted parallelogram using the parameter value sh_y =  and .    (6)

b.   Describe Bresenham’s incremental approach of drawing circle with centre at origin and radius equal to R.                                                              (8)

             c.   Define cubic periodic B-spline.                                                                           (2)

Q.5     a.   What are the two different representations used for storing computer fonts?  Describe each briefly.                                                            (4)

     b.   Describe the stack based seed fill algorithm.                                                       (6)

c.   Using Cohen-Sutherland algorithm find the co-ordinates of the line joining (-1, 2) and (9, 7) which is visible in the rectangle (0, 0) (0, 5) (10, 0) and (10, 5).                                                                 (6)

  Q.6     a. Obtain the transformation matrix for the perspective projection of a 3D object onto 2D plane, which is perpendicular to positive z-axis.           (6)

             b.   Describe an image space method for detecting visible surfaces.                           (4)

             c.   Find the perspective projection of a point (2, 3, 9) with respect to plane       z = 2.  Given that the project reference point is (0, 0, 5).                   (6)

Q.7     a.   What do you mean by homogenous co-ordinates?  Explain its usefulness.            (4)

b.   Show that the composite transformation of rotation and translation operations do not commute.                                                                  (4)

             c.   What do you understand by shading of an object?  Describe Phong’s shading method.                    (8)

Q.8     a.   Enumerate the various steps of animations.  Describe each briefly.                       (8)

             b.   How long will it take to load a  frame buffer with 12 bits per pixel?  If  bits can be transferred per second.                                         (5)

     c.   What is the drawback with bitmap representation of an image?                           (3)

Q.9     a.   Define the following terms:  Amplitude, frequency and envelope.                         (6)

b.   How is sound digitised?  Can we convert digital sound to analogue sound?  If yes, explain briefly.                                                              (5)

c.   What are MIDI files?  How are these played?                                                    (5)