# JNTU previous papers – B-Tech -Ist sem Computer graphics, Aug/Sep 2008

JNTU III B.Tech Supplimentary Examinations, Aug/Sep 2008

COMPUTER GRAPHICS

(Computer Science & Engineering)

SET-II

1. (a) Consider a non interlaced raster monitor with a resolution of n by m (m scan

lines and n pixels per scan line), a refresh rate of r frames per second, a

horizontal retrace time of t horiz and vertical retrace time of tvert. What is

the fraction of total refresh time per frame spent in retrace of the electron

beam.

(b) Explain the applications for large-screen displays. What graphical output

devices support it?

2. (a) Explain the DDA scan conversion algorithm for generating the points on line

segment, when two end-points are given as input.

(b) Digitize the line with end-points (20,10) and (30,18) using DDA algorithm.

3. (a) Perform a 450 rotation of a triangle A(0,0), B(1,1) and C(5,2) about P(-1,-1).

(b) Magnify the triangle with vertices A(0,0), B(1,1) and C(5,2) to thrice its size

while keeping B(1,1) fixed.

4. (a) Draw the flow diagram or a brief step-wise procedure for implementing Sutherland- Hodgeman algorithm.

(b) Consider a convex polygon with n vertices being clipping against a clip rectangle. What is the maximum number of vertices is the resulting clipped window?

What is the minimum number.

5. (a) Describe the phong illumination model. Explain the parameters used in

phong’s model.

(b) List and explain the problems with interpolated shading methods.

6. (a) Derive the quaternion rotation matrix for rotation about an arbitrary axis in

three-dimensional domain.

(b) Classify the perspective projections and explain about each.

7. Write an algorithm for generating a quad tree representation for the visible surfaces

of an object by applying the area subdivision tests to determine the values of the