COMPUTER GRAPHICS DAY1

DEFINITION
Computer graphics is an art of drawing
pictures on computer screens with the help
of programming. It involves computations,
creation, and manipulation of data. In other
words, we can say that computer graphics is
a rendering tool for the generation and
manipulation of images.
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• Computer graphics involves display,
manipulation and storage of pictures and
experimental data for proper visualization
using a computer. It provides methods for
producing images and animations
(sequence of images).
• It deals with the hardware as well as
software support for generating images.
DEFINITION
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Basically, there are four major operations
that we perform in computer graphics:
• Imaging: refers to the representation of 2D
images.
• Modeling: refers to the representation of 3D
images.
• Rendering: refers to the generation of 2D
images from 3D models.
• Animation: refers to the simulation of
sequence of images over time.
DEFINITION
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INTRODUCTION TO IMAGE AND
OBJECTS
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OBJECTS
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COMPUTER GRAPHICS: RELATED AREAS
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OBJECTS
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OBJECTS
• An image is basically representation of a
real world object on a computer. It can be an
actual picture display, a stored page in a
video memory, or a source code generated
by a program. Mathematically, an image is a
two - dimensional array of data with
intensity or a color value at each element of
the array.
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OBJECTS
• Objects are real world entities defined in
three – dimensional world coordinates. In
computer graphics we deal with both 2D
and 3D descriptions of an object. We also
study the algorithms and procedures for
generation and manipulation of objects and
images in computer graphics.
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IMAGE REPRESENTATION
• Image representation is the approximations
of the real world displayed in a computer. A
picture in computer graphics is represented
as a collection of discrete picture elements
termed as pixels. A pixel is the smallest
element of picture or object that can be
represented on the screen of a device like
computer.
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GRAPHICS PIPELINE
• In computer graphics, the graphics pipeline
refers to a series of interconnected stages
through which data and commands related
to a scene go through during rendering
process.
• It takes us from the mathematical
description of an object to its representation
on the device..
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GRAPHICS PIPELINE
The real world objects are represented in
world coordinate system. It is then projected
onto a view plane. The projection is done from
the viewpoint of the position of a camera or
eye.
There is an associated camera coordinate
system whose z axis specifies the view
direction when viewed from the viewpoint.
The infinite volume swept by the rays emerging
from the viewpoint and passing through the
window is called as view volume or view
pyramid. Clipping planes (near and far) are
used to limit the output of the object. 17

GRAPHICS PIPELINE
The mapping of an object to a graphic device requires the
transformation of view plane coordinates to physical device
coordinates. There are two steps involved in this process.
(i) The window to a viewport transformation. The viewport is
basically a sub – rectangle of a fixed rectangle known a logical
screen.
(ii) The transformation of logical screen coordinates to physical
device coordinates.
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GRAPHICS PIPELINE
2D coordinate system to physical device
coordinates transformation.
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GRAPHICS - APPLICATION
Computer-Aided Design:
In engineering and architectural systems, the products are
modeled using computer graphics commonly referred as
CAD (Computer Aided Design).
In many design applications like automobiles, aircraft,
spacecraft, etc., objects are modeled in a wireframe outline
that helps the designer to observe the overall shape and
internal features of the objects. CAD applications are also
used in computer animations. The motion of an object can
be simulated using CAD.
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Presentation graphics:
In applications like summarizing of data of financial,
statistical, mathematical, scientific and economic research
reports, presentation graphics are used. It increases the
understanding using visual tools like bar charts,line
graphs, pie charts and other displays.
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Computer Art:
A variety of computer methods are available for artists for
designing and specifying motions of an object. The object
can be painted electronically on a graphic tablet using
stylus with different brush strokes, brush widths and
colors. The artists can also use combination of 3D modeling
packages, texture mapping, drawing programs and CAD
software to paintand visualize any object.
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Entertainment:
In making motion pictures, music videos and television
shows, computer graphics methods are widely used.
Graphics objects can be combined with live actions or can
be used with image processing techniques to transform
one object to another (morphing)
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Education and training:
Computer graphics can make us understand the
functioning of a system in a better way. In physical systems,
biological systems, population trends, etc., models makes it
easier to understand. In some training systems, graphical
models with simulations help a trainee to train in virtual
reality environment. For example, practice session or
training of ship captains, aircraft pilots, air traffic control
personnel.
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Visualization:
For analyzing scientific, engineering, medical and business
data or behavior where we have to deal with large amount
of information, it is very tedious and ineffective process to
determine trends and relationships among them. But if it is
converted into visual form, it becomes easier to
understand. This process is termed as visualization.
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Image processing:
Image processing provides us techniques to modify or
interpret existing images. One can improve picture quality
through image processing techniques and can also be used
for machine perception of visual information in robotics. In
medical applications, image processing techniques can be
applied for image enhancements and is been widely used
for CT (Computer X-ray Tomography) and PET (Position
Emission Tomography) images.
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Graphical User Interface:
GUI commonly used these days to make a software package
more interactive. There are multiple window system, icons,
menus, which allows a computer setup to be utilized more
efficiently.
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COMPUTER GRAPHICS DAY1

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