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.
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
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
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
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.
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
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.
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.