AMIETE – CS (OLD SCHEME)

 

Flowchart: Alternate Process: DECEMBER 2009Code: AC15                                                                            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.       If we use 12-bit pixel values in a lookup table representation, how many entries does the lookup table have?   

 

(A)    4096                                            (B)  4

                   (C) 1024                                             (D)  8                                                                  

 

b.      An example of a pick device.

 

(A) Tablet                                           (B)  Light Pen

(C) Digitizer                                         (D)  Plotter

            

             c.   This projection technique does not have the direction of projection perpendicular to the viewing plane

                  

(A)    Orthographic parallel projection          (B)  Axonometric parallel projection

(C) Oblique parallel projection                   (D)  None of the above

 

             d.   In Tilting Transformation, the object is   

 

(A)   Rotated about x axis                                     

(B)  Rotated about y axis

(C) Rotated about x axis & then y axis     

(D)  Rotated about y axis & then x axis.

 

             e.   How many bits binary code is used by Cohen Sutherland line clipping algorithm for checking the line that it lies in which region of the plane?                                                         

(A)     one bit                                         (B)  2 bits

(C)  4 bits                                            (D)  8 bits

 

             f.    The polygon is completely within the area:

 

(A)     Surrounding polygon                    (B)  Contained polygon

(C)  Intersecting polygon                      (D)  Disjoint polygon

 

             g.   Lambert’s cosine law states that the intensity of the reflected light depends on  

                    

(A)     Angle of illumination                     (B)  Angle of reflection

(C)  Angle of refraction                        (D)  None of the above

 

             h.   How much time is spent scanning across each row of pixels during screen refresh on a raster system with a resolution of 12801024 and afresh rate of 60 frames per second?

                                

(A)    58 msec                                       (B) 58 sec

(C)  58 micro sec                                (D)  None of the above

 

             i.    Sum of all B-spline blending functions, if curve lies within the convex hull is 

 

                   (A) 1 & all are always +ve                   (B) 0 & all are always +ve

                   (C) 1 & all are always –ve                   (D) 0 & all are always –ve

 

             j.    Transformation matrix for counter clock wise rotation by PHI

 

(A)  -1   0                                           (B)  0     -1

 0   -1                                                1      0

 

(C)  -1    0                                          (D)  0      1

        0    1                                                 -1     0

 

 

Answer any FIVE Questions out of EIGHT Questions.

Each question carries 16 marks.

 

 

  Q.2     a.   When you draw straight lines on a raster graphics terminal aliasing effects will occur. What are they and how do they occur?                                     (8)

       

             b.   What is difference between generation of character by Stroke and Bitmap method? Explain with suitable example.                                              (8)

                 

  Q.3     a.   Reflect the diamond-shaped polygon whose vertices are A(-1,0), B(0,-2), C(0,1) and D(0,2) about the

 

(i)           Horizontal line Y=2

       (ii)    Vertical line    X=2

       (iii)   Line Y=X+2                                                                                (10)

                                                                             

             b.   What is midpoint subdivision algorithm? Explain.                                                 (6)

       

  Q.4     a.   Find a matrix for parallel projection onto the plane 3x + y + 4z +1 =0 when            

 

(i) An orthographic projection is used

(ii) An oblique projection is used.    (10)

 

             b.   Describe Cohen-Sutherland technique for clipping a line with respect  to rectangular window.                                                                    (6)

 

  Q.5     a.   Explain the working and structure of light pen.                                                     (4)

 

b.   Write a 2  2 transformation matrix for each of the following rotation         about the origin.

 

(i)      Counter clockwise by phi.

(ii)     Clockwise by phi /2.                                                                    (6)

 

 

             c.   What is meant by sweep representation of a solid?  How objects can be designed by translational and rotational sweeps?  Explain.                 (6)

 

  Q.6     a.  Find the matrix for mirror reflection with respect to the plane passing through the origin and having the normal vector whose direction is

 

                                   N = i + j + k                                                                                       (8)

       

             b.   Write input devices-handling algorithm. (4)

 

             c.   Explain event handling in brief.                                                                            (4)

 

                          

  Q.7     a.   Derive matrix for perspective projection and explain.                                          (8)   

 

             b.   How DDA differs from Bresenham’s line drawing algorithm?                              (8)          

 

  Q.8     a.   What is morphing?  Write a morphing program to transform a triangle into a quadrilateral.               (4)

                  

             b.   Explain B-spline curve with example.    (8)

 

             c.   What is windowing? Explain its importance.                                                        (4)

 

  Q.9     a.   Derive an illumination model for diffused & specular reflections.                         (8)

 

             b.   Write scan line z-buffer algorithm for solving the hidden surface problem.            (8)