Shekhat M 9727235778 Email vijay shekhatdarshanacin Computer Engineering Darshan Institute of Engineering amp Technology Unit1 Basics of ID: 587708
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Slide1
Prof. Vijay M.
Shekhat
9558045778
vijay.shekhat@darshan.ac.in
2160703
Computer Graphics
Unit-1
Basics of Computer GraphicsSlide2
OutlineWhat is Computer Graphics?Advantages of Computer
Graphics.Application of Computer Graphics.
Basics of Computer Graphics.Various display devices.Raster graphics system.Random graphics system.
Input devices.Graphics software and standard.Slide3
What is
Computer Graphics?
Computer graphics is an art of drawing lines, charts,
pictures, etc. using computers with the help of programming and tools. Computer graphics image is made up of number of pixels. Picture Element (Pixel)
is the smallest addressable graphical unit represented on the computer screen.
Source
: template.netSlide4
Source: http://giphy.com/
Advantages of
Computer Graphics
Most effective and commonly used ways of communication with computer.It provides tools for producing
picture of “real-world” ,synthetic
objects such as mathematical surfaces in 4D and
data that have no inherent geometry such as survey result.Source: http://www.wallpapersxl.com/
Source: http://www.bugman123.com/Source: http://fcpaprofessor.com/Slide5
Source: http://giphy.com//
Contd.
Possible to produce
animations.Can move objects as well as observes as per requirementexample walk through
made by builder to show flat interior and surrounding.
Source: http://www.netanimations.net/Slide6
Source: http://opensourceecology.org/
Application of
Computer
G
raphics
User
interface Example: App iconSimulation and animationExample: Cartoon filmsPlotting of graphs and charts
Example: Stock exchangeComputer aided drafting and design Example: Automobile parts designingSource: https://www.123rf.com
Source: http://www.abc.net.au/Source: http://giphy.com/Slide7
Contd.
Art
and
commerce
Example: Creative picturesCartography
Example: Geographic mapsEducation and training
Example: Models of physicsImage processingExample: Editing Photos
Source: conncoll.eduSource: http://chainimage.com/Source: school-for-champions.comSource
: pinterest.comSlide8
Basics of Computer GraphicsIn computer graphics picture or graphics objects are presented as a collection of discrete pixels.
We can control intensity and color of pixel which decide how picture look like
.The special procedure determines which pixel will provide the best approximation to the desired picture or graphics object, this process is known as Rasterization
.The process of representing continuous picture or graphics object as a collection of discrete pixels is called Scan Conversion.Slide9
Display DevicesDisplay devices are also known as output devices.
Following devices we are going to study:
Cathode ray tube (CRT)Direct-view storage tubes (DVST)Plasma Panels
displaysThin Film Electroluminescent DisplaysLight Emitting Diode (LED)
Liquid Crystal Display (LCD)Three dimensional viewing devices
Stereoscopic system
Virtual-realitySlide10
1. Cathode-Ray-Tubes
Source: http://electronicspost.com/Slide11
Contd.Source: https://youtu.be/GzMh4q-2HjMSlide12
Contd.
There are two techniques used for producing images on the CRT screen:
Vector
scan/Random scan display.
Raster scan display.Source: tutorialspoint.com
ON
OFF
Horizontal Retrace
Vertical Retrace
Source
: eenadupratibha.netSlide13
Architecture of a Vector Display
CPU
I/O Port
Display controller
Keyboard
Mouse
CRT
Display buffer memory
(Interaction data)
(Display command)Slide14
Architecture of a Raster Display
CPU
I/O Port
Display controller
Mouse
T
00000000000000000000001111100000000000000010000000000000000100000000000000001000000000
(Interaction data)
(Display command)
Keyboard
Video controller
CRT
Refresh bufferSlide15
Random Scan v/s Raster Scan
Base of Difference
Raster Scan System
Random Scan System
Electron Beam
The electron beam is swept across the screen, one row at a time, from top to bottom.
The electron beam is directed only to the parts of screen where a picture is to be drawn.
Resolution
Its resolution is
poor.Its resolution is good.Picture DefinitionPicture definition is stored as a set of intensity values for all screen points, called pixels in a refresh buffer area.Picture definition is stored as a set of line drawing instructions in a display file.Slide16
Contd.
Base of Difference
Raster Scan System
Random Scan System
Realistic Display
The capability of this system to store intensity values for pixel makes it well
suited
for the realistic display of scenes contain shadow and color pattern.These systems are designed for line-drawing and can’t display realistic shaded scenes.
Draw i
mageScreen points/pixels are used to draw an image.Mathematical functions are used to draw an image.Slide17
Color CRT MonitorsThere are two basic techniques for color display:
Beam-penetration technique
Shadow-mask techniqueSlide18
Beam-Penetration Technique
In this technique screen is coated with two colours. Outer layer with green and inner layer with red.
Slow speed electron beam strike on red layer and produce red colour. Intermediate speed electron beam strike on red and green layer
and produce two colour orange and yellow.High speed electron beam penetrate red and strike on
yellow layer and produce yellow colour.
Slow Speed Electron Beam
High
Speed Electron Beam
Intermediate Speed Electron BeamSlide19
Shadow-Mask Technique
Source: https://youtu.be/_O-2D5ryb2ASlide20
Cond.
Source
: http://nptel.ac.in/Slide21
Direct-View Storage Tubes (DVST)
Source: graphicsnotes.wordpress.comSlide22
Flat Panel DisplayThe term flat panel display refers to a class of video device that have reduced volume, weight & power requirement compared to a CRT.
We can separate flat panel display in two categories:
Emissive displays: - the emissive display or emitters are devices that convert electrical energy into light.
Ex. Plasma panel, thin film electroluminescent displays and light emitting diodes.
Non emissive displays: - non emissive display or non emitters use optical effects to convert sunlight or light from some other source into graphics patterns.
Ex
. LCD (Liquid Crystal Display).Slide23
Emissive
Displays
Plasma Panels
displays
Thin Film Electroluminescent
DisplaysLight Emitting Diode (LED)
Source: slideshare.net/aroravinay/cg-display-devicesSource: slideshare.net/aroravinay/cg-display-devices
Source: http://66robo.blogspot.in/2012/08/led-excel.htmlSlide24
Non Emissive DisplaysLiquid Crystal Display (LCD)
Source: http://skpang.co.uk/
Source:
eenadupratibha.netSlide25
Cond.Source: https://www.youtube.com/watch?v=_O-2D5ryb2ASlide26
Three Dimensional Viewing Devices
Viewer
Projected 3D image
Timing and Control System
Vibrating Flexible Mirror
CRTSlide27
Stereoscopic & Virtual-Reality Systems
Source: chip.com.tr
Source
: pinterest.comSlide28
Raster Graphics Systems
CPU
System Memory
Video Controller
Monitor
System Bus
I/O Devices
Simple raster graphics systemSlide29
Contd.
Raster graphics system with a fixed portion of the system memory reserved for the frame buffer
CPU
System Memory
Video Controller
Monitor
System bus
I/O Devices
Frame BufferSlide30
Basic refresh operation of video controller
Intensity
Raster Scan Generator
Memory Address
X register
Y register
Pixel register
Frame Buffer
Horizontal and Vertical Deflection VoltagesSlide31
Raster Graphics Systems with a Display Processor
CPU
Display Processor
System Memory
Monitor
System Bus
I/O Devices
Display Processor Memory
Frame Buffer
Video ControllerSlide32
Random-Scan System
CPU
System Memory
Display Processor
Monitor
System Bus
I/O DevicesSlide33
Source: 123rf.com/photo_3854698_working-with-digitizer.html
I
nput
D
evices
Keyboards
MouseTrackball and Space ballJoysticks
Data gloveDigitizerSource: kensington.comSource: commons.wikimedia.org
Source: encyclopedia2.thefreedictionary.com/data+gloveSlide34
Contd.
Image
Scanner
Touch Panels
Touch input can be recorded with following methods.
Optical
methodsElectrical methodsAcoustical methodsLight pensVoice systemsSource: wikihow.com
Source: industrysearch.com.auSource: javatpoint.com/input-devicesSource: http://mastersofmedia.hum.uva.nl/blog/2015/09/14/hey-siri-do-you-spy-on-me/Slide35
Types of Graphics SoftwareThere are mainly two types of graphics software:General programming
package Example
: - GL (Graphics Library)Special-purpose application package
Example: - CAD, medical and business systemsSlide36
Coordinate representationsExcept few all other general packages are designed to be used with Cartesian coordinate specifications.
If coordinate are
specified is some other reference frame they must be converted to Cartesian coordinate before giving input to graphics package.Special-purpose package may allow use of other coordinates which suits application.Slide37
Contd.In general several different Cartesian reference frames are used to construct and display scene.
An initial modeling coordinates position (
xmc, ymc) in this illustration is transferred to a device coordinates position(
xdc, ydc) with the sequence
(xmc, ymc)
(x
wc, ywc) (xnc, ync) (xdc, x
dc).Slide38
Graphic FunctionA general purpose graphics package provides user with Varity of function for creating and manipulating pictures.
Input functions are used for control & process the various input device such as mouse, tablet, etc.
Control operations are used to controlling and housekeeping tasks such as clearing display screen etc.All such inbuilt function in graphics software which we can use for our purpose are known as graphics functionSlide39
Graphics Software and StandardPrimary goal of standardize graphics software is portability.
Some of these standards are
Graphical Kernel System (GKS)Adopted as a first graphics software standard by the international standard organization (ISO) and various national standard organizations including
ANSI.GKS was originally designed as the 2D graphics package and then later extension was developed for 3D.Slide40
Contd.PHIGS (Programmer’s Hierarchical Interactive Graphic Standard
)PHIGS is extension of GKS.
Increased capability for object modeling, color specifications, surface rendering, and picture manipulation are provided in PHIGS.Extension of PHIGS called “PHIGS+” was developed to provide 3D surface shading capabilities not available in PHIGS. Slide41
Thank You