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Unit-1 BLC-501
Computer Graphics Lecture-2
Salim Istyaq (Assistant Professor)
Electrical Engineering Section, University Polytechnic, AMU Aligarh
Computer Graphics- Applications
• CAD (Computer Aided Design)
CAD methods are used in design of building, automobiles, aircrafts, motor crafts, computers, textiles and many other products.
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• Presentation Graphics
Presentation Graphics are used to summarize financial, statistical, mathematical, scientific and economic data for research reports, managerial reports, and consumer information bulletins.
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• Computer art
• Computer Graphics methods are widely used in both fine art and commercial art applications.
• Fine artists use a variety of techniques to produce images.
• Examples include the following:
(I) Paint Brush programs
(ii) Mathematical software packages
• Commercial art makes use of art for logos, TV advertising spots, page layouts etc.
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• Entertainment
Computer Graphics methods are used in making motion pictures, music videos and TV shows e.g. graphics developed for use in the Start rack series.
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• Education & Training
Special systems are designed for training e.g. file simulators for aircraft training.
• Visualization
It is used in numerical model of a storm, modeling space shuttle, models of stream surfaces flowing parts, a space shadow, scientific visualizations or a protein structure and so forth.
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• Image Processing
Commercial Art Applications: that involve retouching and rearranging sections of photos and other art works.
• Medical Applications: Image processing and computer graphics are combined. For ex-Computer aided surgeries where 2D section of the body is obtain using imaging techniques.
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• Graphical User Interface
GUIs are now common in software packages to allow fast selection of processing options and parameter values.
A GUI usually comprises of icons, menus, buttons and windows. Advantages of icons are that they take up less space than their textual descriptions.
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Aspect Ratio
Ratio of number of vertical points to horizontal points necessary to produce equal length lines in both directions on the screen.
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Resolution
• Spot intensity has a Gaussian distribution, so two adjacent spots will overlap.
• The 2 adjacent spots will appear distinct if their separation is greater than the diameter at which a spot intensity has fallen to 60% of maximum.
• The maximum number of spots that will be displayed without overlap is known as the resolution of a CRT.
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Modeling
• Many model reps
Bezier, B-spline, box splines, simplex splines, polyhedral splines, quadrics, super-quadrics, implicit, parametric, subdivision, fractal, level sets, etc (not to mention polygonal)
Modeling
• Physically based
Newton
Behavior as well as geometry
• Materials
Metal, cloth, organic forms, fluids, etc
• Procedural (growth) models
Modeling... is hard
• Complexity
• Shape
• Specifying
• Realistic constraints
• Detail vs concept
• Tedious, slow
Modeling is hard
• Mathematical challenge
• Computational challenge
• Interaction challenge
• Display challenge (want 3D)
• Domain knowledge, constraints
Growth Models
Models
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Example
• Where did this image come from?
• What hardware/software did we need to produce it?
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Preliminary Answer
• Application: The object is an artist’s rendition of the sun for an animation to be shown in a domed environment (planetarium)
• Software: Maya (Maya is a 3D modeling and animation program that can be used for 3D printing, and animated graphics) for modeling and rendering but Maya is built on top of OpenGL
• Hardware: PC with graphics card for modeling and rendering
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Basic Graphics System
Input devices
Output device
Image formed in FB
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CRT
Can be used either as a line-drawing
device (calligraphic) or to display contents of frame buffer (raster mode)
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Computer Graphics: 1950-1960
• Computer graphics goes back to the earliest days of computing
Strip charts Pen plotters
Simple displays using A/D converters to go from computer to calligraphic CRT
• Cost of refresh for CRT too high
Computers slow, expensive, unreliable
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Computer Graphics: 1960-1970
• Wireframe graphics
Draw only lines
• Sketchpad
• Display Processors
• Storage tube
wireframe representation of sun object
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Sketchpad
• Ivan Sutherland’s PhD thesis at MIT
Recognized the potential of man-machine interaction
Loop
• Display something
• User moves light pen
• Computer generates new display
Sutherland also created many of the now common algorithms for computer graphics
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Display Processor
• Rather than have the host computer try to
refresh display use a special purpose computer called a display processor (DPU)
• Graphics stored in display list (display file) on display processor
• Host compiles display list and sends to DPU
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Direct View Storage Tube
• Created by Tektronix
Did not require constant refresh Standard interface to computers
• Allowed for standard software
• Plot3D in Fortran
Relatively inexpensive
• Opened door to use of computer graphics for CAD community
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Computer Graphics: 1970-1980
• Raster Graphics
• Beginning of graphics standards
IFIPS
• GKS: European effort
– Becomes ISO 2D standard
• Core: North American effort
– 3D but fails to become ISO standard
• Workstations and PCs
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Raster Graphics
• Image produced as an array (the raster) of picture elements (pixels) in the frame
buffer
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Raster Graphics
• Allows us to go from lines and wire frame images to filled polygons
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PCs and Workstations
• Although we no longer make the
distinction between workstations and PCs, historically they evolved from different
roots
Early workstations characterized by
• Networked connection: client-server model
• High-level of interactivity
Early PCs included frame buffer as part of user memory
• Easy to change contents and create images
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Computer Graphics: 1980-1990
Realism comes to computer graphics
smooth shading environment mapping
bump mapping
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Computer Graphics: 1980-1990
• Special purpose hardware
Silicon Graphics geometry engine
• VLSI implementation of graphics pipeline
• Industry-based standards
PHIGS
RenderMan
• Networked graphics: X Window System
• Human-Computer Interface (HCI)
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Computer Graphics: 1990-2000
• OpenGL API
• Completely computer-generated feature- length movies (Toy Story) are successful
• New hardware capabilities
Texture mapping Blending
Accumulation, stencil buffers
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Computer Graphics: 2000-2010
• Photorealism
• Graphics cards (GPU) for PCs dominate market
Nvidia, ATI
• Game boxes and game players determine direction of market (Wii, Kinect, etc)
• Computer graphics routine in movie industry: Maya, Lightwave
• Programmable pipelines
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Computer Graphics: 2010-
• Mobile Computing
iPhone
• Cloud Computing
Amazon Web Services (AWS)
• Virtual Reality
Oculus Rift
• Artificial Intelligence
Big Data/Deep Learning Google Car
Thank you.
• Separate Questions sheet will be provided for the practice.
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