K. J. Somaiya Institute of Engineering and Information Technology Sion, Mumbai-22
An Autonomous Institute affiliated to University of Mumbai
Accredited by NAAC and NBA, Approved by AICTE, New Delhi
Department of Electronics Engineering
Computer Graphics
(Subject Code: 1UAIC305)
S Y Artificial intelligence & Data Science Semester-III
Module/Topic Name : 1. Introduction and overview of Graphics system
Ghanashyam Phadke
Asst. Professor
Department of Artificial intelligence and data Sciences
K. J. Somaiya Institute of Engineering and Information Technology
Sion, Mumbai
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sources available on internet
What we will discuss and explore in this module
• Definition and Representative uses computer graphics
• Overview of coordinate systems of Definition of scan conversion
• Rasterization and rendering
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sources available on internet
Definition and Representative uses computer graphics
• Definition:
“Computer graphics deals with generating images with the aid of computers.
Today, computer graphics is a core technology in digital photography, film,
video games, cell phone and computer displays, and many specialized
applications.
A great deal of specialized hardware and software has been developed, with
the displays of most devices being driven by computer graphics hardware. It is
a vast and recently developed area of computer science.
The phrase was coined in 1960 by computer graphics researchers Verne
Hudson and William Fetter of Boeing.
It is often abbreviated as CG, or typically in the context of film as computer
generated imagery (CGI).
The non-artistic aspects of computer graphics are the subject of computer
science research.”
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Definition and Representative uses computer graphics
• Computer graphic is an art of drawing pictures on computer
screen with the help of programming.
• The computer graphic is one of the most effective and
commonly used way to communicate the processed information
to the user.
• It displays the information in the form of graphical objects such
as pictures ,charts ,graphs and diagrams instead of simple text.
• We can say that computer graphics makes its possible to
express data in pictorial form.
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Definition and Representative uses computer graphics
• For our understanding we can split the word “ GRAPHICS” as
“GRAPH” + “PICS”
• Thus by and large we can say it is a visual ( picture/ graph/ text)
displayed on a computer ( or any other digital equipment like mobile
phone) screen
• In earlier days it used to be associated with display on computer
screen but now it has many forms as the “ computer” itself is
available in many shapes. Sizes, forms.
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Definition and Representative uses computer graphics
• cartography
• CAD (visualization of measurement data (2D and 3D))
• visualization of computer simulations.
• medical diagnostics,
• drafting ,
• preparation of publications(DTP),
• special effects in movies,
• computer games.
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CARTOGRAPHY
• Cartography is the study and
practice of making and using
maps. Combining science,
aesthetics, and technique,
cartography builds on the
premise that reality can be
modeled in ways that
communicate spatial
information effectively.
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CAD (visualization of measurement data (2D and 3D))
• Computer-aided design (CAD) is the use of
computers (or workstations) to aid in the
creation, modification, analysis, or
optimization of a design.
• CAD software is frequently used by different
types of engineers and designers. CAD
software can be used to create twodimensional (2-D) drawings or threedimensional (3-D) models.
• The purpose of CAD is to optimize and
streamline the designer's workflow, increase
productivity, improve the quality and level of
detail in the design, improve documentation
communications and often contribute toward
a manufacturing design database. CAD
software outputs come in the form of
electronic files, which are then used
accordingly for manufacturing processes.
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visualization of computer simulations
• computer simulation, the use of a computer to
represent the dynamic responses of one system by
the behaviour of another system modelled after it.
• A simulation uses a mathematical description, or
model, of a real system in the form of a computer
program. This model is composed of equations
that duplicate the functional relationships within
the real system. When the program is run, the
resulting mathematical dynamics form
an analog of the behaviour of the real system, with
the results presented in the form of data.
• A simulation USUALLY takes the form of a
computer-graphics image that represents dynamic
processes in an animated sequence.
•
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Medical diagnostics
• The medical domain provides
excellent opportunities for the
application of computer graphics,
visualization and virtual
environments, with the potential to
help improve healthcare and bring
benefits to patients.
• Example applications
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educational tools;
diagnostic aids;
virtual endoscopy;
planning aids;
guidance aids;
skills training;
computer augmented reality and use of
high performance computing
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Drafting
• Drafting, also spelled draughting,
also called engineering drawing,
graphical representation of
structures, machines, and their
component parts that
communicates the engineering
intent of a technical design to
the craftsman or worker who
makes the product.
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Preparation of Publications(DTP)
• Desktop publishing (DTP) is the
creation of documents using page
layout software on a personal
("desktop") computer.
• This technology allows individuals,
businesses, and other organizations
to self-publish a wide variety of
content, from menus to magazines to
books, without the expense of
commercial printing.
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Special effects in movies
• Computer-generated imagery (CGI) is the
application of the field of computer graphics
(or more specifically, 3D computer graphics)
to special effects.
• CGI is used in films, television programs and
commercials, and in printed media.
• CGI is used for visual effects because the
quality is often higher and effects are more
controllable than other more physically based
processes, such as constructing miniatures for
effects shots or hiring extras for crowd
scenes, and because it allows the creation of
images that would not be feasible using any
other technology.
• It can also allow a single artist to produce
content without the use of actors, expensive
set pieces, or props.
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Special effects in movies
• Ray tracing is the technique modern movies rely on to generate or
enhance special effects. Think realistic reflections, refractions and
shadows. Getting these right makes starfighters in sci-fi epics scream.
It makes fast cars look furious. It makes the fire, smoke and
explosions of war films look real.
• Ray tracing produces images that can be indistinguishable from those
captured by a camera. Live-action movies blend computer-generated
effects and images captured in the real world seamlessly, while
animated feature films cloak digitally generated scenes in light and
shadow as expressive as anything shot by a cameraman.
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Computer games.
• A variety of computer graphic
techniques have been used to
display video game content
throughout the history of video
games. The predominance of
individual techniques have
evolved over time, primarily due
to hardware advances and
restrictions such as the
processing power of central or
graphics processing units.
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Rasterization and rendering
• Rasterization (or rasterisation) is the task of taking an image
described in a vector graphics format (shapes) and converting it into
a raster image (a series of pixels, dots or lines, which, when displayed
together, create the image which was represented via shapes).
• Rendering is the process involved in the generation of a twodimensional or three-dimensional image from a model by means of
application programs. Rendering is mostly used in architectural
designs, video games, and animated movies, simulators, TV special
effects and design visualization. The techniques and features used
vary according to the project. Rendering helps increase efficiency and
reduce cost in design.
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Rasterization
• With rasterization, objects on the screen are created from a mesh of virtual triangles, or polygons, that
create 3D models of objects. In this virtual mesh, the corners of each triangle — known as vertices —
intersect with the vertices of other triangles of different sizes and shapes. A lot of information is associated
with each vertex, including its position in space, as well as information about colour, texture and its
“normal,” which is used to determine the way the surface of an object is facing.
• Computers then convert the triangles of the 3D models into pixels, or dots, on a 2D screen. Each pixel can be
assigned an initial colour value from the data stored in the triangle vertices.
• Further pixel processing or “shading,” including changing pixel color based on how lights in the scene hit the
pixel, and applying one or more textures to the pixel, combine to generate the final color applied to a pixel.
• This is computationally intensive. There can be millions of polygons used for all the object models in a scene,
and roughly 8 million pixels in a 4K display. And each frame, or image, displayed on a screen is typically
refreshed 30 to 90 times each second on the display.
• Additionally, memory buffers, a bit of temporary space set aside to speed things along, are used to render
upcoming frames in advance before they’re displayed on screen. A depth or “z-buffer” is also used to store
pixel depth information to ensure front-most objects at a pixel’s x-y screen location are displayed on-screen,
and objects behind the front-most object remain hidden.
• This is why modern, graphically rich computer games rely on powerful GPUs.
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Image Vectors
What is a Vector?
Vector data are composed of vertices and paths. For example,
the three types of vectors are points, polylines, and polygons.
Vector points are simple XY coordinates in space.
Point Vector Data Type
Polylines connect XY coordinates called vertices with paths.
Vector Data Type Line
Lastly, vector polygons are a set of closed vertices and paths.
Vector Data Type Polygon
And we often store these points, lines and polygons in
shapefiles, geodatabases and various other GIS file formats.
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Rasterization
• Discrete rasters are categorical
and have distinct values
identifying each cell. For
example a land cover raster
might represent urban as the
value 1 and forest as 2.
• Discrete raster
• Continuous rasters are grid cells
with gradual changing data such
as elevation, temperature or an
aerial photograph. Continuous
data is also known as nondiscrete or surface data.
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sources available on internet