Computer Graphics and Architecture - Important Short Questions and Answers: Computer Graphics

1. Define Computer graphics.

Computer
graphics remains one of the most existing and rapidly growing computer
fields.Computer graphics may be defined as a pictorial representation or
graphical representation of objects in a computer.

2. Define refresh buffer/frame buffer.

The
memory area where in picture definition is stored is called Refreshbuffer. This
memory area holds the set of intensity values for all the screen points. On a
black and white system with one bit per pixel, the frame buffer is called a
bitmap.

3. What is pixel?

Each screen point in a monitor is called a pixel/pel. It is also
called picture element.

4. Define aspect ratio.

It is a
property of video monitors. This number gives the ratio of vertical points to
horizontal points necessary to produce equal-length lines in both directions on
the screen.

5. What is Output Primitive?

Basic
geometric structures that describe a scene are referred to as Output
Primitives. Points and straight lines segments are the simplest geometric
components of pictures. Additional output primitives that can be used to
construct a picture include circles and other conic sections, quadric surfaces,
spline curves and surfaces, polygon color areas, and character strings.

6. What is DDA?

The
Digital Differential Analyzer is a scan-conversion line algorithm based on
calculating either difference in y-coordinate (dy) or difference in
x-coordinate. We sample the line at unit intervals in one coordinate and
determine corresponding integer values nearest the line path for the other
coordinate.

7.What are the disadvantages of DDA
algorithm?

Round-off error in
successive additions of the floating-point increment can cause the calculated
pixel positions to drift away from the true line path for long line segments.

Rounding operations and floating-point arithmetic in
procedure are still time-consuming.

8. What is attribute parameter?

Any
parameter that affects the way a primitive is to be displayed is referred to as
an attribute parameter.

9. What are the basic line attributes?

Basic
attributes of a straight line segment are its type, its width, and its color.
10. What is meant by aliasing?

The
distortion of information due to low frequency sampling (Under sampling) is
called aliasing. We can improve the appearance of displayed raster lines by
applying antialiasing methods that compensate for the under sampling process.

11. Define Translation.

A
translation is applied to an object by repositioning it along a straight line
path from one coordinate location to another. We translate a two-dimensional
point by adding translation distances, tx and ty, to original coordinate
position (x, y) to move the point to a new position (x', y'). x' = x + tx, y' =
y + ty. The translation distance pair (tx, ty ) is called a translation vector
or shift vector.

12. Define Rotation.

A 2-D rotation is applied to an object by repositioning it
\along a circular path in the xy plane.

13. Define Scaling.

A scaling transformation alters the
size of an object. This operation can be carried out for polygons by
multiplying the coordinate values (x,y) of each vertex by scaling factors sx
and sy to produce the transformed coordinates ( x', y' ). x' = x. sx, y' = y.
sy.

14. Define Reflection.

A Reflection is a transformation that
produces a mirror image of an object. The mirror image for a 2D reflection is
generated relative to an axis of reflection by rotating the object 180 degree
about the reflection axis.

15. Define Shear.

A transformation that distorts the
shape of an object such that the transformed shape appears as if the object
were composed of internal layers that had been caused to slide over each other
is called a shear.

16. Define Window.

A world-coordinate area selected for display is called a window

17. Define view port.

An area on a display device to which a window is mapped is
called a view port.

18. What is viewing transformation?

The mapping of a part of a
world-coordinate scene to device coordinates is referred to as viewing
transformation.

19. Define Clipping.

Any
procedure that identifies those portions of a picture that are either inside or
outside of a specified region of space is referred to as a clipping algorithm
or simply clipping. The region against which an object is clipped is called a
clip window.

20 What are the types of Clipping?

Point clipping

Line clipping

Area clipping

Curve clipping

Text clipping

21.What is the purpose of presentation
graphics?

Presentation
graphics is used to produce illustrations for reports or to generate 35-mm
slides or transparencies for use with projectors. Presentation graphics is
commonly used to summarize financial, statical, mathematical, scientific, and
economic data for research reports, managerial reports, consumer information
bulletins, and other types of reports.

22. What is frame buffer?

Picture
definition is stored in a memory area called frame buffer or refresh buffer.

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