Code: DC-09 Subject: COMPUTER GRAPHICS

Time: 3 Hours Max. Marks: 100

NOTE: There are 11 Questions in all.

Question 1 is compulsory and carries 16 marks.

Answer any THREE Questions each from Part I and Part II. Each of these questions carries 14 marks.

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

Q.1 Briefly explain: (8 x 2 = 16)

a. Interlacing is refreshing every line on the screen in every refresh cycle.

b. The ambient light is constant for all surfaces in all the directions.

c. Both (1, 2, 3) and (2, 4, 6) represent same point in homogeneous coordinates.

d. MIDI is a compression standard.

e. Using panning, finer details of a part of image can be shown.

f. Mapping of a 3-D object to a 2-D image is geometric transformation.

g. Application of Computer Graphics.

h. Octrees are used to model 3-D objects.

PART I

Answer any THREE Questions. Each question carries 14 marks.

Q.2 a. Modify Bresenhems Circle drawing algorithm to fill the circle with a color. (7)

b. What do you understand by homogeneous coordinates? How do they reduce computations during transformations? (7)

Q.3 a. How does shadow mask method generate colors in raster scan systems? (7)

b. Describe the working of image scanners. (7)

Q.4 a. Magnify the triangle with vertices A(4, 3), B(-2, -3) and C(4, -3) to thrice its size while keeping C fixed. (7)

b. What is Phong specular reflection model? Briefly explain the vectors L, N, R, V and H used in the model. (7)

Q.5 a. Scan convert the line from A(2, -1) to (8, 4) using Bresenhems algorithm. (8)

b. Differentiate between

(i) Bitmapped and outlined font.

(ii) If we want to resize a image to one that is 640 pixels wide with same aspect ratio, what would be height of the resized image. (4+2)

Q.6 a. Clip the line AB (-1, 5) to (3, 8) using midpoint subdivision process. (6)

b. Find a normalization transformation from the window whose lower left corner is at (0, 0) and upper right corner is at (4, 3) onto the normalized device screen so that aspect ratios are preserved. (4)

c. Explain generation of bar charts and pie charts. (4)

PART II

Answer any THREE Questions. Each question carries 14 marks.

Q.7 a. Describe stack based seed fill algorithm with the help of an example. (10)

b. Briefly explain different kinds of light emitting sources? Give examples also. (4)

Q.8 a. Briefly explain CSG method for solid object modelling with the help of examples. (5)

b. Why are hidden-surface algorithms needed? (4)

c. Given points and and a view point determine which points obscure the others when viewed from C. (5)

Q.9 a. Prove the following :

= (4)

b. What do you understand by second order continuity? What are the conditions for getting such continuity in Bezier curves? (6)

c. What are B-spline cubic curves? Give an example of open uniform B-splines? (4)

Q.10 a. Briefly explain the various types of parallel projections. (7)

b. What are the various hardware components required for multimedia applications? What is the necessity of having special hardware for multimedia applications? (7)

Q.11 Write short note on any FOUR: -

(i) Virtual Reality.

(ii) Light Pen.

(iii) Octrees.

(iv) Hypertext and its advantages.

(v) Windows Paint Brush. (3.5 x 4 =14)