DipIETE – CS (OLD SCHEME)

Code: DC09                                                                            Subject: COMPUTER GRAPHICS

Time: 3 Hours                                                                                                     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 the best alternative in the following:                                 (2 10)

a. The homogenous co-ordinates (8, 4, 2) represents a point in ________ dimension.

(A)  one                                              (B)  two

(C)   three                                            (D)  none

b. The aspect ratio of a monitor having width of four pixels equal to height of three pixels is equal to _____.

(A) 1                                                  (B)

(C) (D)  none

             c.   The compounds which have a crystalline arrangements of molecules but flow like liquid are

(A)  light emitting diodes.                    (B) thin film plasma.

(C)  liquid crystal.                                (D) none.

             d.   A common device for drawing, painting or interactively selecting co-ordinate positions on an object is

(A)  optical pen.                                 (B)  mouse.

(C)  data glove.                                   (D)  graphics tablet.           

             e.   Which of the following is/are the problem(s) of scan conversion?

(A) staircase appearance                    (B)  unequal brightness of slanted lines

(C)  picket fense problem                    (D)  all of these

             f.    In Bresenham’s line drawing algorithm when the  and (decision parameter) < 0 the next to plot is  

(A) . (B) .

(C) . (D)  none.

             g.   The following composite transformation matrix  represents (s > 1) a transformation which

(A) reduces object about (3, 4).        

(B) magnifies object about (3, 4).

(C)  rotates the object about (3, 4) in clockwise direction. 

(D) rotates the object about (3, 4) in anti clockwise direction.

             h.   The objects at a distance look smaller because of

(A) vanishing points.                           (B) direction of projection.

(C) perspective foreshortening.            (D) none of the above.

             i.    The parallel projection onto XY plane in the direction of projection  is given by  where p is equal to

(A) -c. (B) .

(C) 1.                                                  (D)  -1.

             j.    What is the maximum number of objects that can be presented by using         z-Buffer algorithm?

(A)  1                                                  (B)   10

(C)  100                                              (D)   Infinite

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

Q.2     a.   Describe the following terms:  persistence, resolution, frame buffer, interlacing of scanlines.              (6)

             b.   How is computer graphics used in entertainment and education?                          (3)

c. Describe the construction and working of the liquid crystal display.                      (7)

Q.3     a.   Write the names of five input devices and one application of each.                       (8)

             b.   Using DDA algorithm find the co-ordinates of first four pixels of the line joining (20, 50) and (30, 45).                                                                    (8)

Q.4     a.   Describe briefly rubber band method.  (4)

b.   Using Bresenham’s circle drawing algorithm give the location of pixels for a circle with centre at (1, 1) and radius equal to 9 (first five pixels only). (8)

             c.   What are the boundary conditions of a Bezier curve having (n+1) control points?                (4)

Q.5     a.   Describe various ways of generating characters.                                                  (8)

     b.   What are the advantages of B-splines over Bezier curve?  Give an example of open uniform B-spline which reduces to Bezier curve giving proper explanation.                                                              (8)

  Q.6     a. How are code assigned to regions in line clipping Cohen-Sutherland algorithm?  Can this technique be extended to 3D, justify?                       (5)

             b.   Using stack based 4-connected seed fill algorithm give the location of first five filled pixels with respect to the region given by (3, 1) (3, 8), (10, 8) and (10, 1).  The initial seed is (6, 5)           (8)

c.   Discuss briefly how ray-casting methods can be used for solid modelling.            (3)

Q.7     a.   What do you mean by oblique parallel projection?  What are the two main oblique parallel projection, describe briefly.                                   (4)

b.   Find the perspective projection of a point P(x, y, z) onto the plane Z=  and (0, 0, ) as centre of projection.  Use 3D homogenous coordinate representation.                                               (8)

c.   What are homogeneous coordinates?  What are they used for?                           (4)

Q.8     a.   Describe Phong’s specular reflection model including attenuation factor.              (8)

             b.   How are self hidden faces removed using back face detection method?  Explain.                 (8)

Q.9     a.   Describe briefly the various applications of multimedia.                                        (8)

b.   What are the various commonly used image formats?  Describe each briefly.                       (8)