CS2401-COMPUTER GRAPHICS - KEY

VII - SEMESTER- CS2401-COMPUTER GRAPHICS - KEY

PART-A

1. Write the two phases in Cohen Sutherland algorithm.

Identify those lines which intersect the clipping window and no need to clipped

Perform the clipping

2. Write the formula for viewport transformation.

(Xv-Xvmin)/(Xvmax-Xvmin)= (Xw-Xwmin)/(Xwmax-Xwmin)

3. Specify two advantages of B-splines curves.

The degree of a B spline polynomial can be set independently of the number of control points.

B-Spline allow local control over the shape of aspline curve or a surface.

4. What are quadratic surfaces?

The quadratic surfaces are the describe with second degree equations.

5. What is OPENGL?

OpenGL stands for Open Grapics Library. OpenGL provides a set of commands to render a three dimention scene.

6. Write the types of library available for OPENGL.

OpenGL Utility Library(GLU)

OpenGL Utility Toolkit (GLUT)

7. State the Lamber's law.

The relationship between brightness and surface orientation

8. What is shadow buffer?

An auxillary second depth buffer, is employed for each light source.It contains "depth picture" for the scene from the point of view  of the light source.

9. Give the rules for dragon curves.

the rules that used X and Y for dragon curves

F ? F

X ? X+YF+

Y?-FX-Y

Atom=FX

F means "draw forward"

-means "turn left 90 degree"

+ means turn right 90 degree"

10. What is known as surface texure?

Surface texure, also known surface finish, is the characteristics of a surface in which computer generated images is made more likvely and realistic by paining texture on various surfaces.

PART-B

11. a)         Explain in detail about the Cohen Sutherland line clipping.

Process that identifies the portion of a picture that are either inside or outside of a specified region is referred as clipping

conditions followed

1. Tw end points are coming inside the boundary of clipping window

2.Two enpoints are coming outside with 2 intersection

3.One end point coming outside with one intersection

4.Two end points are coming outside with no intersection

Draw diagram for all these conditions

finding region code for each end point

1- represents that the point is inside tha clipping boundary

0- represents that the point is outside the clipping boundary

Find the intersection point using formula

Y = Y1+M(X-X1)

M= (Y2-Y1)/(X2-X1)

X=X1+(Y-Y1)/M

b)         Briefly explain the polygon clipping with suitable example.

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

draw sample diagrams

clipping procedure

1.If  1 st 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

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

12. a)         Discuss briefly about the visualization of data set.

b)         Explain in detail about the different 3D projections with example.

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)         Explain briefly about the basic graphics primitives of OPENGL.

OpenGL is designed as a streamlined, hardware-independent interface to be implemented on many different hardware platforms. To achieve these qualities, no commands for performing windowing tasks or obtaining user input are included in OpenGL; instead, you must work through whatever windowing system controls the particular hardware you're using. Similarly, OpenGL doesn't provide high-level commands for describing models of three-dimensional objects. Such commands might allow you to specify relatively complicated shapes such as automobiles, parts of the body, airplanes, or molecules. With OpenGL, you must build up your desired model from a small set of geometric primitives - points, lines, and polygons.

            The following diagram shows the Henry Ford assembly line approach, which OpenGL takes to processing data. Geometric data (vertices, lines, and polygons) follow the path through the row of boxes that includes evaluators and per-vertex operations, while pixel data (pixels, images, and bitmaps) are treated differently for part of the process. Both types of data undergo the same final steps (rasterization and per-fragment operations) before the final pixel data is written into the framebuffer.

Order of Operations

14. a)         Explain how to add surface texture to faces of a mesh object.

b)         Describe about the procedure to create and manipulate the camera in OpenGL.

 programming.

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.