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.