· Question 1 is compulsory and carries 28 marks. Answer any FOUR questions from the rest. Marks are indicated against each question.
· Parts of a question should be answered at the same place.
c. While performing polygon scan conversion, how do you treat the case when a scan line passes through a vertex of the polygon?
d. Define the terms:
(i) foreshortening factor
(ii) floating Horizon
(iii) B-spline curve
e. Discuss the relative merits and demerits of Z-buffer hidden surface elimination algorithm over scan line Z-buffer algorithm.
f. Describe the diffuse and specular light reflection modelling in computer graphics.
g. Write short notes on:
(i) half-toning (ii) CSG models (74)
Q.2 a. Describe the Boundary fill algorithm.
b. Using the parametric approach of Cyrus-Beck line clipping algorithm compute the visible portion of the line segment joining P(15, 0) and Q(15, 40) for the window area given by: P0(10,10), P1(20, 10), P2(20, 30) and P3(10,30). Show all the calculations. (8+10)
Q.3 a. A triangle ABC is given with vertices being A(3, 5), B(7, 5) and C(5, 10). Find the transformation to obtain its reflection about the line y = 4x. Also find the coordinates of the reflected triangle.
b. A unit cube located at the origin is rotated about the X-axis by 45 degrees counter clockwise direction and then projected on the z = 0 plane with centre of projection at
( 0, 0, –10 ). Find the matrix transformation of the above projection? (8+10)
Q.4 a. Using integer Bresenham circle generation algorithm determine the coordinates of the points on the arc of the circle in the 1st octant with centre at (0, 0) having radius 7 units. Show all the calculations.
b. Derive the transformation matrix to obtain isometric projection of an object. Use this to obtain the screen coordinates of a rectangular box. Work out XY screen points corresponding to object coordinates A(0, 0, 10), B(0, 20, 10), and C(30, 10, 0) (9+9)
Q.5 a. Explain in detail depth-buffer hidden surface removal algorithm. What are its advantages and disadvantages in comparison with scan line z-buffer algorithm?
b. Describe the method of constructing terrain model as an example of fractals? (10+8)
Q.6 a. Control points for a cubic Bezier curve are given by:
p0=(10, 0), p1=(20, 20), p2=(40, 20) and p3=(50, 0). Find the parametric equations of the curve. Draw a rough sketch of the curve.
b. Explain briefly how are the vanishing points obtained in perspective projection.
c. Discuss the method of choosing the root node of a Binary Space Partitioning Tree. (6+6+6)
Q.7 a. Describe in detail the Gouraud shading algorithm. Also state its advantages over the Phong’s shading algorithm.
b. State the components of the traditional animation.
c. Explain a method of simulating acceleration at the beginning followed by de-acceleration at the end between two given key frames in an animation clip. (8+4+6)