Computer Graphics

To understand Computer Graphics, we should

know what the Graphics are:

Graphics are visual presentations on some surface,

such as a wall, canvas, computer screen, paper, or

stone to brand, inform, illustrate, or entertain.

Examples are photographs, drawings, graphs,

diagrams, symbols, geometric designs, maps,

engineering drawings, or other images.

Computer Graphics is a field of computerscience in which we are interested ingenerating objects and images using pixels.

Early computer graphics were Vector

graphics, composed of thin lines

whereas modern day graphics are

Raster based using pixels. Pixel also known as picture element,

is a single point in a raster image. Each pixel has its own address. The intensity of each pixel is variable.

In color image systems, a color istypically represented by three or fourcomponent intensities such as red,green, and blue, or cyan, magenta,yellow, and black.

Passive Graphics

Offline graphics.

Once a graphics

program is

developed, the user

has no control over

it.

Ex- Static Web page.

Interactive Graphics

Online graphics.

User can

dynamically control

the display on the

monitor.

Ex- Cartoons, Video

games, Dynamic

Websites.

Components of Computer GraphicsInteractive Computer Graphics mainly has three components:

Digital memory buffer:- This is a place where the images or pictures are stored in an array form (0 represents darkness and 1 represents image or picture). This is also known as Frame Buffer or V-RAM (Video RAM), it also helps to increase the speed of Graphics.

Monitor:- Monitor helps us to view the display.

Display Controller:- It is an interface between Digital memory buffer and Monitor. Its job is to pass the contents of frame buffer to the monitor. This passing has to be fast for steady display on the monitor. In today’s terms, Display controller is known as Display Card and one of our choices can be VGA (Video Graphics Array) card.

Types of Images Bitmap image, also referred to as raster image is

made up of pixels or bits (binary digits) of information arranged on a grid. Each bit can be visualized as a dot. In simple words, it could be stated that when one draws a line, one is covering pixels.

Vector images are mathematical arrangements of points. These points are connected by mathematical formulae. Thus these images can be stretched and shrunk without changing the initial quality of the image. Almost all of the images are made by straight lines connected at nodes or points. However, one can create a curve that is absolutely smooth. The nodes can be manipulated to form smooth curves. The techniques involved in drawing programs differ markedly from those used in painting programs.

Graphics CardA video card, video adapter, graphics accelerator card, display

adapter, or graphics card is a expansion card which generates output

images to a display. Most video cards offer added functions, such as

accelerated rendering of 3D scenes and 2D graphics, video capture, TV-

tuner adapter, MPEG-2/MPEG-4 decoding, FireWire, light pen, TV output,

or the ability to connect multiple monitors (multi-monitor). Other

modern high performance video cards are used for more graphically

demanding purposes, such as PC games.

Components

A modern video card consists of a printed circuit board on which the

components are mounted. These include:

Graphics Processing Unit

A GPU is a dedicated processor optimized for accelerating graphics. The

processor is designed specifically to perform floating-point calculations,

which are fundamental to 3D graphics rendering and 2D picture drawing.

The main attributes of the GPU are the core clock frequency, which

typically ranges from 250 MHz to 4 GHz and the number of pipelines

(vertex and fragment shaders, which translate a 3D image characterized

by vertices and lines into a 2D image are formed by pixels.

Modern GPUs are massively parallel, and fully programmable. Their

computing power is orders of magnitude higher than that of CPUs. As

consequence, they challenge CPUs in high performance computing, and

push leading manufacturers on processors.

Video BIOS

The video BIOS or firmware contains the basic program, which is usually

hidden, that governs the video card's operations and provides the

instructions that allow the computer and software to interact with the

card. It may contain information on the memory timing, operating speeds

and voltages of the graphics processor, RAM, and other information. It is

sometimes possible to change the BIOS (e.g. to enable factory-locked

settings for higher performance), although this is typically only done by

video card overclockers and has the potential to irreversibly damage the

card.

Video memory

Video memory may be used for storing other data as well as the screen

image, such as the Z-buffer, which manages the depth coordinates in 3D

graphics, textures, vertex buffers, and compiled shader programs.

APPLICATIONS OF

COMPUTER GRAPHICS

Computer Aided Design (CAD)Computer-aided design (CAD) is use of a wide range of computer based tools that:

assist engineers, architects and other design profession in their design activities.

main geometry authoring tool within the Product Lifecycle Management process.

involves both software and sometimes special-purpose hardware. Current packages range from 2D vector base drafting systems to 3D solid and surface modelling.

CAD is one part of the whole activity within

the Product Lifecycle Management (PLM)

process, and as such is used together with

other tools, which are either integrated

modules or stand-alone products, which are:-

Computer-aided engineering (CAE)

Computer-aided manufacturing (CAM)

Digital Mock-Up(DMU)

Photo realistic rendering

Computer-aided manufacturing (CAM) use of computer software to control machine

tools and related machinery in the manufacturing of workpieces.

use of a computer to assist in all operations of a manufacturing plant, including planning, management, transportation and storage.

Its primary purpose is to create a faster production process and components and tooling with more precise dimensions and material consistency, which in some cases, uses only the required amount of raw material (thus minimizing waste), while simultaneously reducing energy consumption

Computer-Aided Engineering (CAE)

Use of computer systems to analyze CAD geometry

Allows designer to simulate and study how the product will behave, allowing for optimization

Finite-element method (FEM) Divides model into interconnected elements Solves continuous field problems

VISUALIZATION…

Data is boring, information is interesting!

No one is really interested in looking at a large number of data rows, or even a small one.

As humans, we tend to better understand a particular issue when it is presented to us in a visual way.Scientists, engineers, medical personnel, business analysts, and others often need to analyze large amounts of information or to study the behavior of certain processes. Numerical simulations carried out on supercomputers frequently produce data files containing thousands and even millions of data values. Similarly, satellite cameras and other sources are amassing large data files faster than they can be interpreted. Scanning these large sets of number to determine trends and relationships is a tedious and ineffective process. But if the data are converted to a visual form, the trends and patterns are often immediately apparent.

Visualization is any technique for creating

images, diagrams, or animations to

communicate a message.

Visualization through visual imagery has been

an effective way to communicate both

abstract and concrete ideas.

Examples from history include cave

paintings, Egyptian writings and Greek

geometry.

Visualization today

has ever-expanding

applications in

science, engineering,

all forms of

education, interactive

multimedia, medicine

etc.

Fields of Visualization Data visualization is a related subcategory of visualization

dealing with statistical graphics and geographic or spatial data that is abstracted in schematic form.

Scientific visualization is a branch of science, "primarily concerned with the visualization of 3D phenomena (architectural, meteorological, medical, biological, etc.), where the emphasis is on realistic renderings of volumes, surfaces, illumination sources, and so forth, perhaps with a time component".

Terrain rendering Climate visualization[12]Atmosphere

Educational visualization is using a simulation normally created on a computer to create an image of something so it can be taught about.

Product Visualization involves visualization technology for the viewing and manipulation of 3D models, technical drawing and other related documentation of manufactured components and large assemblies of products. It is a key part of Product Lifecycle Management. Product visualization software typically provides high levels of photorealism so that a product can be viewed before it is actually manufactured.

Visual communication is the communication of ideas through the visual display of information. Primarily associated with two dimensional images, it includes: alphanumerics, art, signs, and electronic resources.

Music visualization, a feature found in electronic music visualizers and media player software, generates animated imagery based on a piece of music. The imagery is usually generated and rendered in real time and synchronized with the music as it is played.

Visualization techniques Constructing isosurfaces

direct volume rendering

Streamline, streaklines, and pathlines

table, matrix

charts (pie chart, bar chart, histogram, function graph, scatter plot, etc.)

graphs (tree diagram, network diagram, flowchart etc.)

Maps

treemap - a visualization technique aimed at hierarchical data

Venn diagram

Euler diagram

Chernoff face

Hyperbolic trees

brushing and linking

Cluster diagram

Ordinogram

ANIMATION

Applications of Computer Animation

Entertainment

Motion pictures

Cartoons

Advertising

Scientific studies

Engineering studies

Training

Education

Video games

ANIMATION

The word “animation” is a form of “animate,”

which means to bring to life.

Thus when a multimedia developer wants to

bring an image to life, animation is used.

What is Animation??? refers to any time sequence of visual changes

in a scene.

transforming one object shape into another.

Most precisely, Animation is the rapid

display of a sequence of 2-D or 3-D images

model positions in order to create an illusion

of movement.

Principles of AnimationAnimation is possible because of a biological phenomenon known as persistence of vision

And

The psychological phenomenon called phi .

An object seen by the human eye remains chemically mapped on the eye’s retina for a brief time after viewing.

Combined with the human mind’s need to conceptually complete a perceived action.

This makes it possible for a series of images that are changed very slightly and very rapidly, one after the other, seem like continuous motion .

Persistence of vision Persistence of vision allows a series of

separate images to blend together into a visual illusion of movement.

The phenomenon of the eye by which an afterimage is thought to persist for approximately one twenty-fifth of a second on the retina.

In simple words "persistence of vision" refers to that phenomenon in which the human perception of the decay of a visual stimulus is slower than the true decay of that stimulus. An image will stay on one's eye for a brief amount of time after its cause has, in reality, disappeared.

Theory of Motion Perception

There are two distinct perceptual illusions: phi

phenomenon and beta movement

phi phenomenon: This optical illusion is based in

the principle that the human eye is capable of

perceiving movement from pieces of

information.

for example, a succession of

images. In other words, from a

slideshow of a group of images

at a certain speed of images per second, we are

going to observe constant movement.

Beta movement:

It is an optical illusion in which the fixed images

seem to move, even though of course the image

does not change.

Static images do not physically change but give

the appearance of motion because of being

rapidly changed faster than the eye can see.

for example, set of LEDs.

These are individually controlled, but our eyes

and brains perceive them as a ball is running in

the square picture. This is also seen commonly

on LED writing boards.

DESIGN OF ANIMATION SEQUENCES

In general, an animation sequence is designed

with the following steps:

Storyboard layout

Object definitions

Key-frame specifications

Generation of in-between frames

Storyboard layout: a series or a set of rough

sketches or photographs showing the sequence of

shots or images planned for a film.

Object definition: An object definition is given

for each participant in the action. The

associated movements for each object are

specified along with the shape.

Key-frame specification: A key-frame is a

detailed drawing of the scene at a certain time

in the animation sequence. Within each key

frame, each object is positioned according to

the time for that frame.

In-between frames: In-betweens are the intermediate

frames between the key frames. The number of in-

betweens needed is determined by the media to be

used to display the animation. Film requires 24

frames per second, and graphics terminals are

refreshed at the rate of 30 to 60 frames per second.

Typically, time intervals for the motion are set up so

that there are from three to five in-betweens for

each pair of key frames. Depending on the speed

specified for the motion, some key frames can be

duplicated. For a I-minute film sequence with no

duplication, we would need 1440 frames. With five

in-betweens for each pair of key frames, we would

need 288 key frames. If the motion is not too

complicated, we could space the key-frames a little

farther apart.

Techniques of Animation: Cel animation: It is based on changes that occur from

one frame to the next. Cel stands for celluloid which is a clear sheet with images drawn on them. The celluloid images are place on a background that is usually stationary. The background remain fixed as the images changes.

Rotoscoping: It is a technique where animators trace live-action movement, frame by frame. Originally, recorded live-action film images were projected onto a frosted glass panel and re-drawn by an animator.

Stop-motion animation: It is used to describe animation created by physically manipulating real-world objects and photographing them one frame of film at a time to create the illusion of movement. There are many different types of stop-motion animation, usually named after the type of media used to create the animation.

i) Puppet animationii) Clay animation

2D animation: 2D animation figures are created and/or edited on the

computer using 2D bitmap graphics or vector graphics.

This includes automated computerized versions of

traditional animation techniques such as of tweening,

morphing and rotoscoping.

In traditional 2D animation, pictures are hand-drawn and

every one showing very slightly changes from the previous.

When played back sequentially, it creates the illusion of

motion. In stop motion animation, real life models are

moved slightly and filmed. Again, the pictures will create

the illusion of motion when played back.

2D animation has many applications, including Flash

animation and PowerPoint animation. Cinemagraphs are

still photographs in the form of an animated GIF file of

which part is animated.

3D animation:

The process of creating 3D animation can be

sequentially divided into three phases:

Modeling - which describes the process of

creating the 3D objects within a scene

layout and animation - which describes how

objects are positioned and animated within a

scene.

rendering - which describes the final output of

the completed computer graphics.

2D Animation Softwares

Pencil-Pencil is an animation/drawing software

for Mac OS X, Windows, and Linux. It lets you

create traditional hand-drawn animation

(cartoon) using both bitmap and vector graphics.

Pencil is free and open source.

Claymation- Claymation Studio is perfect for

beginning animators because of its easy-to-use

interface.It uses a storyboard interface for

animation creation, which allows you to see all

of the frames in sequence.

3D Animation Softwares

Autodesk 3ds Max - The most popular 3d software on Windows platform. Character Studio being a great character animation tool often used for animating computer games characters.

Maya 3d- The most used 3d software in Film industry.

Autodesk Softimage- By many users considered to have the best 3d animation tools.

Blender 3d- the most popular free and open source 3d animation software

IMAGE

PROCESSING

In computer graphics, a computer is used to

create a picture. Image processing, on the other

hand applies techniques to modify the existing

pictures.

A technique in which the data from an image are

digitized and various mathematical operations

are applied to the data, in order to create an

enhanced image that is more useful or pleasing

to a human observer, or to perform some of the

interpretation and recognition tasks usually

performed by humans.

Set of computational techniques for analyzing,

enhancing, compressing, and reconstructing

images.

Two principal applications of image

processing are:

improving picture quality

machine perception of visual information,

as used in robotics.

Components of Image processing

Its main components are:

Importing, in which an image is captured

through scanning or digital photography

through digital camera.

Analysis and manipulation of the image, in

which digital methods can be applied to

rearrange picture parts, to enhance color

separations, or to improve the quality of

shading achieved by using various

specialized software applications

Output (e.g., to a printer or monitor).

Applications of Image processing: Agricultural (Fruit grading, harvest control, seeding)

Communications (video conferencing)

Character recognition (printed and handwritten)

Commercial (Bar code reading, bank cheques, signatures)

Document processing (Electronic circuits, mechanical

drawings)

Leisure and entertainment (museums, film industry,

photography)

Medical (X-rays, CT scan, MRI’s, Ultrasound)

Military (Tracking, detection, radar)

Police (Fingerprints, DNA analysis, biometry)

Traffic and transport (Road, airport, seaport, license

identification, Number plates identification)

Remote sensing via satellites and other spacecrafts

Fundamental steps in Digital Image

Processing

Image acquisition is the first process. To do so requires an

imaging sensor and the capability to digitize the signal

produced by the sensor. The sensor could be a color

camera or also be a line-scan camera that produces a

single image line at a time. If the output of the camera or

other imaging sensor is not already in digital form, an

analog-to-digital converter digitizes it. Note that

acquisition could be as being given an image that is

already in digital form. Generally, the image acquisition

stage involves preprocessing, such as scaling.

Image enhancement improves the quality (clarity) of

images for human viewing. Removing blurring and noise,

increasing contrast, and revealing details are examples of

enhancement operations. Basically, the idea behind

enhancement techniques is to bring out detail that is

obscured, or simply to highlight certain features of

interest in an image.

Image restoration is an area that also deals with improving

the appearance of an image. However, enhancement,

which is subjective, image restoration is objective, in the

sense that restoration techniques tend to be based on

mathematical or probabilistic models to recover image

from distortions to its original image.

Color image processing is an area that has been gaining in

importance because of the significant increase in the use

of digital images over the Internet. Color is used as the

basis for extracting features of interest in an image.

Compression deals with techniques for reducing the

storage required to save an image, or the bandwidth

required to transmit it.

Morphological processing deals with tools for extracting

image components that are useful in the representation

and description of shape

Segmentation procedures partition an image into its

constituent parts or objects. In terms of character

recognition, the key role of segmentation is to extract

individual characters and words from the background.

Recognition is the process that assigns a label (e.g.,

“vehicle”) to an object based on its descriptors.

Knowledge base, Knowledge about a problem domain is

coded into an image processing system in the form of a

knowledge database. It is a special kind of database for

knowledge management, providing the means for the

computerized collection, organization, and retrieval of

knowledge, also a collection of data representing related

experiences, their results are related to their problems

and solutions.

More Applications

PRESENTATION GRAPHICS It is used to produce illustrations for reports

or to generate slide for with projections.

Examples of presentation graphics are bar

charts, line graphs, surface graphs, pie

charts and displays showing relationships

between parameters.

3-D graphics can provide more attraction to

the presentation.

COMPUTER ART

Computer graphics methods are widely used

in both fine are and commercial art

applications.

The artist uses a combination of 3D modeling

packages, texture mapping, drawing

programs and CAD software.

Pen plotter with specially designed software

can create “automatic art”.

“Mathematical Art” can be produced using

mathematical functions, fractal procedures.

These methods are also applied in

commercial art.

ENTERTAINMENT CG methods are now commonly used in making

motion pictures, music videos and television

shows.

Animations are also used frequently in

advertising, and television commercials are

produced frame by frame. Film animations

require 24 frames for each second in the

animation sequence.

A common graphics method employed in many

commercials is morphing, where one object is

transformed into another.

Graphics objects can be combined with a live

action.

EDUCATION AND TRAINING

Computer-generated models of physical,

financial and economic systems are often

used as educational aids.

For some training applications, special

systems are designed.

Eg. Training of ship captains, aircraft pilots

etc.,

Some simulators have no video screens, but

most simulators provide graphics screen for

visual operation. Some of them provide only

the control panel.

GRAPHICAL USER INTERFACE

Nowadays software packages provide

graphics user interface (GUI) for the user to

work easily.

A major component in GUI is a window.

Multiple windows can be opened at a time.

To activate any one of the window, the user

needs just to check on that window.

Menus and icons are used for fast selection of

processing operations.

Icons are used as shortcut to perform

functions. The advantages of icons are which

takes less screen space.

Virtual reality

Computer-simulated environments that can

simulate physical presence in places in the

real world, as well as in imaginary worlds.

The simulation of a real environment for

training and education.

Eg. Flying Simulation to train pilots.

The development of an environment for

Gaming.

With virtual-reality systems, the designers

can go for a simulated walk inside the

building.