CS2401-COMPUTER GRAPHICS - KEY

VII - SEMESTER- CS2401-COMPUTER GRAPHICS - KEY

PART-A

1.         Write the scale transformation matrix.

2.         List out some advantages of DDA algorithm.

It is simplest the algorithm and it does nto require special skill for implemantation

It is faster method

I t eleminates the multiplication in the equation by making use of raster characteristics

3.         List out any two properties of Bezier curve.

Any curve position is simply the weighted sum of the control point position

The convex hull property of a bezier ensures that the polynomial smoothly follows the control points without erratic oscillations.

4.         Give examples for Quadratic surfaces.

Spheres,ellipsoids ,torus,paraboloidsand hyperboloids.

5.         What is DAG?

Directed acyclic graph. used to represent the scene of complex object.

6.         List the viewing functions of OPENGL.

glortho()

gkortho2d()

glviewport()

7.         Write the types of Shader.

GL-VERTEX-SHADER

GL-FRAGMENT-SHADER

GL-DELETE-SHADER

GL-ATTACH-SHADER

8.         What is known as lateral inhibition?

Edges between faces appear more pronounced than they would be on an actual physical object because of  a phenomenon in the eye known as lateral inhibition.

9.         Give some examples of fractals.

clouds, grass,fire,branches of tree,cracks in the pavement

10.       What is known as peano curve?

A space filling curve is a curve whose fractal dimention is 2 and it completely fills a region of space.

 space filling curves in the 2 dinmentional plane are commonly called peano curves.

PART- B

11.       a)         Explain in detail about the polygon clipping with example.

 Clip a polygon by processing the polygon boundary as a whole against each window edge. Each and every vertex in polygon is checked against the clipping boundary.

draw sample diagrams

clipping procedure

1.If  1st vertex is outside, 2 nd vertex is inside the boundary  point

intersection point and 2 nd vertex will be taken in the output list.

2.If both vertex are inside, only 2 nd vertex is taken in output vertex.

3.If 1 st vertex is inside ,2 nd vertex in outside boundary  only the intersection point is taken

2.If both are outside , nothing will be stored.

b)         Explain the various attributes of output primitives with example.

Explain line, point,text , filling attributes

color tables and buffer should be explained

12.       a)         Briefly explain about the 3D viewing and clipping with suitable example.

Explain what is viewing

draw viwing pipeline

transformation of world and viewing coordinates

explain projection concepts

clipping concepts.

b)         Explain the properties of beziercurve. How it is differ from B-Spline.

Bezier curves are used in computer graphics to produce curves which appear reasonably smooth at all scales (as opposed to polygonal lines, which will not scale nicely). Mathematically, they are a special case of cubic Hermite interpolation (whereas polygonal lines use linear interpolation). What this means is that curves are constructed as a sequence of cubic segments, rather than linear ones. But whereas Hermite interpolating polynomials are constructed in terms of derivatives at endpoints, Bezier curves use a construction due to Sergei Bernstein, in which the interpolating polynomials depend on certain control points. The mathematics of these curves is classical, but it was a French automobile engineer Pierre Bezier who introduced their use in computer graphics.

Roughly speaking, to each set of four points P₀, P₁, P₂, P₃ we associate a curve with the following properties:

* It starts at p0 and ends at p3.

* When it starts from p0 it heads directly towards p1, and when it arrives at p3 it is coming from the direction of p2.

* The entire curve is contained in the quadrilateral whose corners are the four given points (their convex hull).

13.       a)         What is animation? Explain the steps to design an animation sequence.

An animation sequence is designed with the following steps.

Story board layout 

Object definition

Key frame specification

Generation of in between frames

b)         How do you implement morphing animation technique? Discuss with an example.

Morphing is a special effect in motion pictures and animations that changes (or morphs) one image into another through a seamless transition. Most often it is used to depict one person turning into another through technological means or as part of a fantasy or surreal sequence.

14.       a)         Discuss about the process of creating shaded objects with example.

b)         Explain briefly about how to do shadows to objects.

15.       a)         What is iterated function system(IFS)? Explain in detail.

IFS stands for Iterated Function System. Fractals of this type are created by applying one of a number of functions, chosen randomly from the rules set up for the IFS, repeatedly to an intitial point, and graphing each new point. IFS stands for Iterated Function System. Fractals of this type are created by applying one of a number of functions, chosen randomly from the rules set up for the IFS, repeatedly to an intitial point, and graphing each new point.

b)         Explain in detail about the Julia set.