Page 59 - DCAP504_Computer Graphics

Computer Graphics

4.8 Self Assessment

1. State whether the following statements are true or false:
(a) Various patterns are obtained on the computer screen by highlighting the required pixels.
(b) In computer graphics, a line refers to a line segment, which is a part of a straight line that
extends definitely in opposite directions.
(c) A sector is the portion of area that an arc creates in a circle.

2. Fill in the blanks:
(a) The instrument used for scan conversion is known as ………………….
(b) The…………………………… algorithm is one of the highly efficient incremental methods for
scan-converting lines.
(c) Ellipse is a …………………….symmetry.

3. Select the suitable choice for every question:
(a) How many methods for changing a picture’s data rate exist?
(i) One (ii) Two (iii)Three (iv) Four
(b) Bresenham’s line algorithm is one of the highly efficient incremental methods for scan-
converting which among the following?

(i) Line (ii) Circle (iii)Ellipse (iv) Polygon
4.9 Review Questions
1. “Even though an arc appears to be part of a circle, it is not possible to draw the arc using
Bresenham’s circle drawing algorithm.” Do you agree? Justify.
2. “The process of representing continuous graphics objects as a collection of discrete pixels is known
as scan conversion or rasterization.” Elaborate.
3. “The Digital Differential Analyzer (DDA) algorithm is one of the incremental scan-conversion
methods characterized by calculating at each step using the results obtained in the previous step.”
Explain with the help of an example.
4. “Bresenham’s algorithm can be successfully used for drawing lines on a computer screen,
subtracting, and bit shifting.” Discuss.
5. “It is very important to consider all the three elements θ1, θ2, and radius while constructing the
arc.” Do you agree? Justify.
Answers: Self Assessment

1. (a) True (b) True (c) True
2. (a) Scan Converter (b) Bresenham’s line (c) four-way
3. (a) Two (b) Line
4.10 Further Readings

K. Malay, Pakhira , Computer Graphics, 2 Ed.
nd

N.S.Amarendra, D.U.Arun, Computer Graphics, The McGraw-Hill Companies

http://whatis.techtarget.com/definition/0,,sid9_gci212200,00.html
http://www.tutornext.com/perimeter-polygons/909

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