Code: DC-09                                                                          Subject: COMPUTER GRAPHICS

Time: 3 Hours                                                                   Flowchart: Alternate Process: December 2005                                  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.       The graphical symbol that is designed to look the processing option it presents is a 

 

                   (A)  Cartoon                                       (B)  Wireframe.

(C)    Icon.                                           (D)  Fractal.

       

b.      Which one of the following is used for summarising statistical, mathematical and economical data?

 

(A)    Presentation graphics package.     (B)  Computer aided design package.

(C)  Animation package.                      (D)  Image processing package.

            

             c.   In random systems picture definitions are stored as

                  

(A)     a set of line drawing intensity values.

(B)     a set of line drawing instructions.

(C)     a bitmap.                                    

(D)     a pinmap.

 

             d.   Which transformation have general property that parallel lines are transformed into parallel lines?

 

(A)    workstation transformation.         (B)  commutative transformation

(C)  rigid body transformation.            (D)  affine transformation.  

 

             e.   The transformation matrix  represents reflection about

                  

(A)     x = Axis                                       (B)  y = Axis

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

 

 

 

 

 

             f.    The ordinary co-ordinate corresponding to homogeneous co-ordinate (9, 6, 3) is  

 

(A)     (9, 6)                                           (B)  (6, 3)

(C)  (9, 3)                                           (D)  (3, 2)

 

             g.   A B-spline curve with (n+1) blending function has

 

(A)     n control points.                           (B)  (n+1) control points.

(C) (n-1) control points.                       (D)  n2 control points.

 

             h.   Which one of the following is one of the blending functions for Bezier curve (cubic)?

 

(A)    3u2                                    (B) u2

(C) 3u3                                                (D) u (1-u)2

 

             i.    Which one of the following is used to represent solids in medical imaging?

 

(A)   CSG.                                           (B) Sweep.

(C) Octree.                                         (D) BSP.

 

             j.    The out code of the points in clip-window, in Cohen-Sutherland algorithm, is

 

(A)  1000                                            (B)  0000

(C)  0001                                            (D) 1111

 

 

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

 

  Q.2     a.   Describe the construction and working of a typical light pen.                               (8)

       

             b.   How is computer used in commercial art?                                                           (3)

 

             c.   Describe the relevance of “shadow masks” in CRT displays. Give its construction also.                   (5)

            

  Q.3     a.   How can a straight line be drawn using rubber band method?                              (3)

 

             b.   Give a general 33 transformation matrix involving rotation and translation only. What are the properties satisfied by upper-left 22 submatrix?                                                                (3)

 

             c.   Give the pixel positions of a circle with centre at (0,0) and radius 9. Use Bresenham’s algorithm.                                                                (8)                                                             

 

             d.   Draw a Bezier curve by hand with four control points P1, P2, P3, P4.                    (2)

                  

 

 

 

  Q.4     a.   Derive a composite matrix for a rotation about x-axis through an angle followed by an equal amount of rotation about y-axis.                           (4)

 

             b.   For the case given above: What will be the new co-ordinates for a unit cube after a rotation of .                                                                      (4)

 

             c.   Find the perspective projection of a point (x, y, z) with respect to plane z=d. The projection reference point being                                     (8)                                                             

 

  Q.5     a.   What do you mean by vanishing point? What for do we need vanishing point?                     (4)

       

             b.   Find the vanishing point with respect to plane z = 4 when the projectors are parallel to the join of points (2, 3, 4) and (7, 5, 6).                               (6)

 

             c.   Give the steps for finding intersection of two octrees.                                          (6)

 

  Q.6     a.   Describe Phong’s specular reflection model.                                                       (5)

 

             b.   What are the similarities between Bezier and B-spline curves?                             (5)

 

             c.   Describe mid point subdivision line clipping algorithm.                                         (6)

 

  Q.7     a.   Discuss briefly the construction of Pie-chart. Give its two applications.                (4)   

 

             b.   Using the scan line oriented seed fill algorithm, fill the polygon with exterior vertices at (2, 1), (2, 6), (8, 6), (8, 5), (10, 5), (10, 4), (11, 4),       (11, 1).  Given seed as (6, 4).                                      (9)

 

             c.   Give the composite transformation matrix in 2D for scaling followed by rotation.                 (3)

 

  Q.8     a.   Derive the transformation matrix for oblique parallel projection on the plane z=0. Given that oblique projection line makes an angle  with a particular line on the projection plane. Make your own assumptions, if required.                                                                                                         (8)

 

             b.   Give the intensity function for N point sources of light, which includes  attenuation factor also. If the colour of scene is expressed in terms of  RGB system,  what will be the change in the intensity function?         (6)

 

             c.   Give simplest form of conditions for smooth join of two curve segments.              (2)

 

  Q.9     a.   What is a WAV file? Explain briefly.    (5)

 

             b.   What are various image formats? Describe each briefly the utility of each.            (6)

 

             c.   How is multimedia helpful in improving the working of an organisation? Describe.                (5)