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.

CS2401-COMPUTER GRAPHICS - KEY

VII - SEMESTER- CS2401-COMPUTER GRAPHICS - KEY

PART-A

1. What is called output primitives?

Graphics programming packages provide functions to describe a scene in terms of the basic geometric structures are called output primitives

2. What are the types of text clipping?

all or none character clipping

all or none string clipping

3. Differentiate interpolation and approximation splines.

Interpolation curves are used to digitize drawings or to specify animation paths

Approximation curves are used as design tools to structure object surfaces

4. Define convex hull.

The convex polygon boundary that encloses a set of control points is called the convex hull.

5. Define morphing.

Transformation of one shape to another shape.

6. Write different phases of animation development.

·         Story board layout

·         keyframe generation

·         Inbetween frame generation

·         Object Definition

7. Specify types of reflection mapping.

chrome mapping

environment mapping

8. Write the applications of texure rendering.

·         Repeating a rendered image multiple times in a scene

·         simulating reflection effects , like a mirror or lake in a scene.

·         simualting shadows effects in a scene.

·         Post proceeding effects such as motion blur or antialiasing

·         compositing a rendering image in to a 3D GUI

encounters with virtual objects.

9. What are the three types of self similarity found in fractals?

Exactly self similar

quasi self similarity

statistically self similar

10. What is known as L system?

L system (also known as Lin denmayer systems or parallel string - rewrite systems) is a simple approch to generate a large number of complex curves by refining the line segments baesd on a simple set of rules.

PART-B

11. a)         Explain briefly about the midpoint algorithm for drawing ellipse.

read rx ,ry and center point (xc,yc)

F_{ellipse(x,y)=}ry²x²  +rx²y²-rx ²ry ²

F_ellipse(x,y)={^{<0 if (x,y) is inside the ellipse    , =0  if (x,y) is on the ellipse ,  >0 if  (x,y) is outside of ellipse}}

derive decition parameter for region 1 p10=ry² -rx^2ry+1/4 rx²

derive decition parameter for region 2 p20=ry²(x0+1/2)²+rx²(y0 -1)²-rx²ry²

write algorithm with midpoint diagram

b)         Discuss in detail about the 2D transformation with suitable example.

Translation

Rotation

Scaling

Reflection

Shearing

write definition,formula,matrix,diagram.

12. a)         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).

b)         Explain briefly about the 3D polygon representation with example.

13. a)         Explain in detail 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

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

                       

 Programming.

b)         Explain in detail about flat and smooth shading with example.

15. a)         Explain briefly about the Julia set with suitable example.

b)         Explain in detail about the adding surface texure.

CS2401-COMPUTER GRAPHICS - KEY

VII - SEMESTER- CS2401-COMPUTER GRAPHICS - KEY

PART-A

1. Write down the equation for Cartesian slope intercept.

y=mx+b

m- slope of the line

b is the y intercept                                                        

2. Differentiate window and view port.

window defines what is to be viewed

viewport defines where it is to be defined

3. What is parallel projection?

Parallel projection is a method to project points on the object  surface along parallel lies on to the display plane.

4. What is perspective projection?

Perspective projection is a method to project points to the display plane along converging paths.

5. Specify the purpose of color model.

Color model are used to represent behaviour and effectiveness of colors.

describes Purity, Brightness and hue.

6. Write different types of motion specifications.

Direct motion specification

Goal directed motion specification

Dynamic and kinematic specification

7. What are two types of smooth shading?

Gouraud shading

phone shading

8. What is shading model?

The shading model attempts to model how light that emanates from light sources would interact with objects ina scene. the shading model dictates how light is scattered or reflected from surfaces.

9. List out some properties of fractals.

Self similar

Formatted by iteration

Fractional dimension

Form is extremely irregular or fragmented

10. What is ray tracing?

Ray tracing also called as ray casting , it is a technique for generating an image by tracing the bath of light through pixels in an image and simulating the effects of its encounters with virtual objects.

PART-B

11. a)         Explain in detail about the Bresenhams line drawing algorithm. (16)

read starting and end point.

derive decision parameter po

draw diagram 

calculate remaining points

b)         Briefly explain about the midpoint algorithm for drawing the circle.      (16)

read r and center point (xc,yc)

F_circle(x,y)=x²  +y²-r ²

F_circle(x,y)={^{<0 if (x,y) is inside the ellipse    , =0  if (x,y) is on the ellipse ,  >0 if  (x,y) is outside of ellipse}}

derive decition parameter po=5/4 -r

write algorithm with midpoint diagram

12. a)         Explain briefly about the 3D transformations with example.                   (16)

Explain translation, rotation,scaling

also explain composite transformation

b)         Explain in detail about the 3D viewing and clipping.                                (16)

Explain what is viewing

draw viwing pipeline

transformation of world and viewing coordinates

explain projection concepts

clipping concepts.

13. a)         Describe HSV, XYZ, CIE,CMYand RGB color model.                            (16)

RGB and CMY Color Models

1.

HSV Solid

2.

b)         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

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

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

15.       a)         Explain in detail about Mandelbrot set.    

The Mandelbrot set is a mathematical set, a collection of numbers. These numbers are different than the real numbers that you use in everyday life. They are complex numbers. Complex numbers have a real part plus an imaginary part. The real part is an ordinary number, for example, -2. The imaginary part is a real number times a special number called i, for example, 3i. An example of a complex number would be -2 + 3i.

The number i was invented because no real number can be squared (multiplied by itself) and result in a negative number. This means that you can not take the square root of a negative number and get a real number. When you take the square root of a number, you find a number that can be squared to get that number. The number i is defined to be the square root of -1. This means that i squared is equal to -1. So when you square an imaginary number you can get a negative number. For example, 3i squared is -9.

Real numbers can be represented on a one dimensional line called the real number line. Negative numbers like -2 are plotted to the left of zero and positive numbers like 2 are plotted to the right of zero. Any real number can be graphed on the real number line.

Since complex numbers have two parts, a real one and an imaginary one, we need a second dimension to graph them. We simply add a vertical dimension to the real number line for the imaginary part. Since our graph is now two-dimensional, it is a plane, the complex number plane. We can graph any complex number on this plane. The colored dots on this graph represent the complex numbers [2 + 1i], [-1.5 + 0.5i], [2 - 2i], [-0.5 - 0.5i], [0 + 1i], and [2 + 0i].

Graphing the Mandelbrot set

The Mandelbrot set is a set of complex numbers, so we graph it on the complex number plane. However, first we have to find many numbers that are part of the set. To do this we need a test that will determine if a given number is inside the set or outside the set. The test is based on the equation Z = Z² + C. C represents a constant number, meaning that it does not change during the testing process. C is the number we are testing, the point on the complex plane that will be plotted when testing is complete. Z starts out as zero, but it changes as we repeatedly iterate this equation. With each iteration we create a new Z that is equal to the old Z squared plus the constant C. So the number Z keeps changing throughout the test.

We're not really interested in the actual value of Z as it changes, we just look at its magnitude. The magnitude of a number is its distance from zero. For example, the number -9 is a distance of 9 from zero, so it has a magnitude of 9. The magnitude of a complex number is harder to measure. To calculate it, we add the square of the number's distance from the x-axis (the horizontal real axis) to the square of the number's distance from the y-axis (the imaginary vertical axis) and take the square root of the result. In this illustration, a is the distance from the y-axis, b is the distance from the x-axis, and d is the magnitude, the distance from zero.

As we iterate our equation, Z changes and the magnitude of Z also changes. The magnitude of Z will do one of two things. It will either stay equal to or below 2 forever, or it will eventually surpass two. Once the magnitude of Z surpasses 2, it will increase forever. In the first case, where the magnitude of Z stays small, the number we are testing is part of the Mandelbrot set. If the magnitude of Z eventually surpasses 2, the number is not part of the Mandelbrot set.

b)         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 initial 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 initial point, and graphing each new point.