Tuesday, June 21, 2011

Global Warming


Greenhouse effect does not allow escape of reflated radiation from earth to space. Due to this, the reflected radiation come back to earth surface and finally increase the atmospheric temperature  Therefore, the mean ambient temprature of earth is continuously increasing at the rate of 0.5 to per1 degree centigarte per decade. It is known as global warming.

Some of the predicted effects of global warming are discussed here:

1. Ozone depletion : -
The concentration of carban di oxide in air, which is most responsible greenhouse gas, is continously increasing. It is also influcing the depletion of ozone layer in atmosphere which protect life on earth from U.V. radiation coming from the sun.

2. Seal level : -
Warming of the earth's atmosphere i.e. global warming will lead to warming of the upper layer of the ocean which lead to the tharmal expansion of  water. The expansion raises the sea level. Increasing sea level is also     responsible for submergence of many low lying coasted areas.

3. Effect on species distribution : -
Due to global warming, distribution of different species or organisms also change from altitude and latitude. Many species are migrating towards polar areas due to moderately high temprature.
Rapid rise i temprature also cause death of tree which are temperature  sensitive. Due to this, many species are going to disapper because they  are migrate fast according to desired temprature.

4. Food production : -
In temprature region, small rise in temprature may enhance the crop productivity but larger temprature change will decrease the crop productivity.Global warming reduces drop productivity or food production due to increased plant diseases, pets, weeds etc.desite of beneficial carbon di oxide fertilization effect.

5. Marine ecosystem : -
Due to increasing concentration of carbon di oxide ocean are expected to absorb more and more carban di oxide and decompose in the form of carbonic acid.

6. Effect on weather and climate : -
Due to global warming, the average mean temprature of earth is expected  to increased by 1.4 degree to 5.8 degree centigrate by the year 2100 from year 1900. It increases the moisture carrying capacity of the atmosphere and also changes the precipitation pattern at deficient latitudes. Precipitation is more at higher latitude and less at lower latitude.

Monday, June 20, 2011

Central Processing Unit Part-II


Secondary Storage : -

There are many different type of secondary storage devices. For example: - Magnetic tape,floppy disk, magnetic disk,optical disk.

Magnetic Tape : -

Manetic tape is an older device for secondary storage  though it is very popular even at the present. 
 *  Magnetic tape can virtually staore data of unlimited quantity because many tapes can be used.
 * Magnetic tape is low cost secondary storage device.
 * Magnetic tape reels are easy to store and handle. 

Magnetic Disk : -

Magnetic disk is the most widely used direct-access secondary storage medium today. A magnetic disk is thin, circular metal plate/platter coated  on both sides with a magnetic meterial. There are two kinds of magnetic disk and floppy disk. A hard disk resembles a thin steel platter with an iron oxide coating. Floppy disk is used in microcomputer.

Floppy Disk :-

A floppy disk is used as a medium of direct access secondary storage  for minicomputer systems. A floppy disk is also reffered to as diskettle or floppy, the latterbeing more comman.A floppy disk is made of flexible plastic which is coated with magnetic oxide. The disk is enclosed within a square plastic or card boared  jacket, often reffered to as a cartridge. Floppy disk are typically 3.5, 5.25, or 8 inches in diameter.

Optical Disk : -

Optical disk are increasingly becoming popular for secondary storage. An optical disk also called compact disk or laser optical disk.There are three ways inwhich data are stored-compact disk read only memory (CD-ROM), write once/read many (WORM), and magneto- optical disk.

Compact Disk Read Only Memory(CD-ROM): -

The most common optical disk system used with microcomputers  is known as CD-ROM. It is a 4.75 inch compact disk that can store  upto 660 megabyte. A CD -ROM is read only memory no new data can be written on these but can be only read. That is why CD-ROMs are used for reference materials with massive amount of data, such as encyclopedias, directories, or online databases and for storing multi media  applications that combine text, images, and sound.

Friday, June 17, 2011

Central Processing Unit Part-1


Central processing unit (CPU)is the most important part of computer system and manipulate symbols, numbers,and letters and controls other parts of the computer system. A CPU has three element primary storage, airthmatic logic unit (ALU), and control unit.

Primary storage : -

Primary memory also known as main memory,core memory,or immediate access storage, provides capability to store input data, statements from currently undergoing processing, data resulting from processing, and data in preparation for output. Data and programs are placed in primary storage before processing, between processing step, and after processing has ended,piror to being returned to secondary storage or realesed as output.

Types of semiconductor memory : -

A semiconductor is an integrated circuit made by printing  of numerous transistor on a small sillicon chip. There are several types of semiconductor memory used in primary storage. These may be two categories-Random access memory and read only memory.

Random access memory (RAM): -

RAM is a read/write memory. It is called random access because each seperate location(address) inside the memory can be accessed as easily as any other location and takes the same amount of time. RAM is extremely fast but can also be expensive. RAM is used for short term storage of data or programes instructions.

Read only memory(ROM) : -

ROM provide permanent memory storage, that is, informaton is written permanently into the memory. Data can only be read from the memory but cannot be written there. ROM is normally used to store information that the computer may need frequently for its own operation.
There are two suclasses of ROM-
1. Programmable read only memory (PROM). 
2.  Erasable programmable  read only memory(EPROM).


Arithmatic logic unit: -

Arithmatic logic unit(ALU) is used for arithmatical operations, such as addition,subtractions, multiplication, divisons,etc. In ALU the logic part used for operations ,such as comparing, selecting, matching, and sorting/merging of data.For comparing to numbers by subtracting one numberfrom the other, adder in ALU is used.

Control unit : -

Control unit, also known as nerve center of a computer system, controls and coordinates all the activities of the computer and monitors the execution of any program being processed.The CU controls and cordinates the different components of the components of the computer  inthe same way as the brain directs the action of human body.The CU does not perform the actual processing on the  data  but direct the flow of sequence of operations. The series of operations required to process a machine instruction is called the machine cycle.

Thursday, June 16, 2011

Computer System


Information System of the present area are highly dependent on computers, either small or large size, depending on the requirements of individual organisations. 
The literal meaning of computer is a large machine carrying out calculations of several stages automatically. To be more precise, computer is a programmable machine with two characteristics:  
(1) It responds to a specific set of instructions in well-define manner
(2) It can execute a prerecorded list of instruction
Various physical component of a computer-cables, transistors,circuits,etc. are known as hardware.

Type of computer: -
There are many types of computers and there are many ways in which these can be classified. There are:
1. By the type of data computers are capable of manipulating-analog and     digital;
2. By the purpose for which these are designed -general purpose and     dedicaed;
3. By their memory size and processing capabilities- super computer,mainframe, minicomputer,microcomputer and workstation.

1. Analog and digital computers : -

An analog computer measures continuous electrical and physical magnitudes like voltage,pressure,shaft rotation, water flow,etc.and  reacts in a predefined way to changes in the specified quantity.Thus, it works as a process control device. An analog computer has the ability to accept inputs which vary with time and intensity and directly apply them to various devices within the computers which performs the computing operations.

Analog computer are used in scientific and industrial fields for stimulating various physical systems or automatically controlling industrial processes.  A digital computer operates directly on decimal digits that represent either discreate data or sysmbols.It takes input and gives output  in the form of numbers, lettrers, and special characters.

2. Super computers : -

A super computer is the largest,fastest, most powerful, and most expensive computer that can perform very complex computation involving hundreds of thousand of variable factors.
The speed of super computer are  measured in nanosecond(one billionth of asecond) and gigaflop(one billion flotting-point airthmatic operations per seconds). Super computers can perform upto128  gigaflops, and use bus width of 32 or 64.

3. Mainframe computer : -

Mainframe computers are widely used computers  in large bussiness. Indial railways use mainframe for  reservation. Mainframe computer system is usually  composed of several computers of comparatively smaller capacity in addition to the mainframe, or host processor.
Generally, Mainframe have 50 megabytes to over 1 gigabytes  of random access memory(RAM). 

4. Minicomputer :-
Minicomputers started in late 1960s, and Digital equipment corporation of the USA launched its first minicomputer, DEC PDP-8 in 1968. A minicomputer works on the principle of the mainframe except that in a minicomputer, there are smaller number  of computer terminals and  it has lower memory capacity,usually ranging between 10 megabytes to 1 gigabytes. The main use of minicomputer is in the field of education, local government,etc. besides in business. In bussiness, minicomputers are used for invoicing ,inventory control, payroll,sales analysis, etc.

Micro computer : -

A microcomputer also terned as miniaturised computer and incomman parlance as personal computer, is one that can be placed on desktop or carried from one place  to another. Microcomputers are built arround microprocessor  chips  with layers of etched and printed circuits,containing all the elements required to process binary encoded data. A typical microcomputer has a keyboard  for input and uses tape cassette players and / or flopy disk drive to enter to enter data and programs and to retrives outputs. Many microcomputers also use small magnetic tapes and floppy disks for off line secondary storage.

Workstation : -

A workstation is a powerful desktop computer which has mathematical and graphics  processing capability. Workstations are mostly used by engineers, architects, and another professionals who need detailed graphic displays. For example, in designing machine parts, on the basis of which technical capability of the part is measured  and suitable amendments are made for finalising design.
Workstation  are also called as supermicros because they look like microcomputers but the chips  inside make the difference between  the two. Most workstation use reduced instruction set computer (RISC) microprocessor.

Wednesday, June 15, 2011

Operating System


In order to operate computer, besides hardware and software we need something special, which can allow computer users to interact with computer is called as "operating system". In other terms, we can say that an operating system is a broker that acts as an intermidiatry between user of the computer  and the hardware.
The operating syatem as a disk manager performs following activities :
* Free space management
* Stroage allocation
* Disk scheduling
* Storage deallocation
There are many type of operating system:-


1. Batch operating system
2. Multi programming system
3. Time sharing system
4. Real time operating system
5. Multi processor operating system
6. Distributed Operating system

Batch operating system : -

This form of operating system was used in the earlier age. This system was developed when magnetic tapes were used for loading and unloading of the program. In this operating system, the programs were executed in a sequential fashion in batches. Suppose we recieve  3 programs A, B and C where A is a FORTRAN program, B is a basic program and C is FORTRAN  program. Then, as a part of early system, there will be loading and unloading time for basic interpreter and running the object code and again there will be loading and unloading time for FORTRAN compiler and running of the object code etc.

Multiprogramming system : -

Initially only one program was under execution, But with the advent of new methods and spooling, it was possible to keep more than one program into the main memory. This resulted  into multi programming operating system. In this type of operating system, more than one program  will reside into main memory.
The multi programming system has problem related with debugging and also loading of software libraies in anticipation for user. This resulted into a new technology, called as time sharing system, which is logical extension of multi programming. Example of operating systems which support multi programming are UNIX,WINDOWS 98 etc.

Time sharing system : -

Multi programmed batch system provide an enviorment, where various system  resources (like CPU,memory,I/O devices) were effectively utilised. In this time sharing system, the time of cpu is shared between multiple programs residing in the main memory. multiple jobs are executed by the CPU, switching between them, but the switch occurs so frequently that the user may not interact with other programs simultaneously while it is running. Example of time sharing operating system are multics,cal,UNIX etc.

Real time operating system : -

Real time operating system is a special purpose operating system designed for rigid time requirments on the operation of the processor or flow of data. real time operating system has well defined fixed time constraints.
These type of operating systems are used in process Industry, where a delay in action may result into serious action. One of the simple examples is power plant, chemical industry etc. Example is TOSDIC of toshiba system.`.


Multiprocessor operating system : -

As the name indicates, this is an operating system  where more than one process is active at atime. For a multi-processing system, multi programming is very essential. Multi Processing system can be symmetric or asymmetric. If it is a symmetric multi processing, then each processor run on same operating system, whereas in case of asymmetric multi processing, each processor is assigned a specific task and thus operating system may differ.

Distributed system : -

Here, each processor has it's own local memory and clock, communicate to other processor through communication each processor lines, such as high speed buses ,telephone line, VSAT etc. That is why sometime distributed system are also called as loosely coupled system. The main reasons for building of distributed system are computation speed up, Resource sharing, Reliability etc.

Tuesday, June 14, 2011

Software Development Life Cycle(SWDLC)


Introduction : -

 A software Development life cycle (SWDLC) is an abstract representation of gradual development and evolution of the software the undergoes a series of sequential or concurrent step of the sowtware development process. Each of these steps in the development of a software product which may be either a minor oe major component of the software system in contribution to the completion of the system. 
The sofyware development  life cycle consist of following steps.

Requirement analysis--> Design-->Coding-->Module level testing--> 

Integration and system testing-->Delivery, Implementation and maintenance

1. Requirement analysis : -
    This step is the first and primary step of software development life cycle which analyzes the requirment of the software. It is performed after the feasibility study has been done. The requirment term in this concern can be understood as : -

 * A condition or capability needed bya customer to solve a problem,and.
 * A condition or capability that must be met by a system, software, document, manual,report etc.

Design : -

This step is devided into two level designing named as, preliminary designhigh level design and detailed design or low level design.

premilinary design concern the brief overview of the software architecture and structure rather than goes into the details of the modules in detail in the detailed design. As the result of this step, it produces the software design specification(SDS) SDS is built to have.

 * A software architecture in the layered  sequential layout
 * Data structure, algorithums,control structure
 * The interfaces required for the software, and,
 * The satisfaction that requirments have been met in the design.

Coding : -

This is the phase that produces the actual code that will be delivered to the customer as the operational product. To develop the code, a specific progrmming language is chosen either through its features or directly specified  by the customer.

Module level Testing : -

Individual developed modules are tested here. It is also called as the unit testing. The testing is performed for each of the module separately.

Integration and system designing : -

All the modules are collected and integrated appropriately with each other. Interface are provided among them, and then the whole system is tested fully.

Delivery, implementation and maintenance : -

Once the complete system is tested then that system is delivered to the customer who will implement it on its organisation site. After delivery, any modification or changes can be made to help in maintenance.

This is the complete software development life cycle. This is the basic general  process which is followed to develop each software product. 

Monday, June 13, 2011

System Development Life Cycle -2




Analysis : -

when the feasibility study is completed and the control mechanism is in place, the project team concentrates on the analysis part.

" Analysis is a detailed study of the various operations performed by a system and their relationship with in and out side of the system"

1. Define the scope of the new system.
2. Understand the old information system.
3. Analyse the current system to find the deficiencies in it.
4. Develop the structured functional specification for the new system.
5. Review the feasibility and cost benefit analysis.

A key prossblem in this phase is - what must be done to solve the problem?

Design : -

System design  is the determination of the processes and data that are required by a new system. When the system is computer-based, the design can include a specification of the types of equipment to be used. so, it can said that:
The degign describes a final system and the process by which it is developed. If refers to the technical specification that will be applied in implementing the system.

Implementation and testing : -

 After developing the code (or manufacturing) of the system, it enters into the implementation and testing phase. The implementation phase is less creative than the system design. it is primarily concerned with user training, site preparationand file conversion. It is defined as :
 Implementation is theacquisition and integration of the physical and conceptual resources that produce a working system.
Additionally, the final testing of the complete system is performed to user satisfication and supervision of the initial operation of the new system. During the final testing, user acceptance is tested, followed by user training.

Maintenance : -

Once the system has settled down and been running for some time, the system analyst may be involved in amendment of procedures to adapt the system to changing conditions, in auditing the system to check thast the stated objectives of system are still valid in the present enviorment and in evaluating the achivement of those objectives. So, periodic maintenance of hardware and software are required.

Review and Evolution : -

A review is conducted whether the system objectives are being met with the user requirments and what are the problems in the smooth running. Step are taken to resolve them. This is an audit by the designer for improvements through test  data and audit trails.
Each organisation adopts its own apporach to system development and the apporach will be defined in its data processing standards. For example, Some data procssing departments will merge the initial and detailed studies together into an investigation and outline design phase which includes an assessment of feasibility; other will not bother about feasibility in certain circumstances. During investigation, ideas for improvements and redesign will emerge and during detailed design, a return  to the user department will often be necessary.

Saturday, June 11, 2011

System Development Life Cycle -1


System development life cycle is also known as the system life cycle, problem-solving cycle, system development cycle, system development process and system study.Perheps,the simplest view of this life cycle is a sequence of tasks, an apporach that was used in the early days of developing computer based system.

A system development life cycle is  the evolutionary process that is followed in implementing a computer-based system or subsystem. A system development life cycle is a framework consisting of a series of various different tasks to achieve the specific centralized objective in the development of a system. SDLC is an application of the systems apporach to the task of developing and using computer-based system. As such the SDLC is a methodology but its pattern is being influenced by their need to develop the system more quickly.

Various phase of SDLC : -
The system development life cycle consist of seven major phases :
(a) Preliminary Assessment
(b) Feasibility study
(c) Analysis
(d) Design
(e) Implementation and testing
(f) Maintenance
(g) Review and evolution

Preliminary Assessment : - 

The first phase of any project is the preliminary assessment. The base of this phase is recognition of needs for improving an information system or a procedure. This need leads to a preliminary survey or initial  investigation  to determine  whether an alternative system  can solve the problem. This brief  investigation of the system underconsideration will be provided to the organizations streeing team and any project team, a set of items of reference for more detailed work.
There are various external and internal  sources  to be described , as given below :
1. Goverment polices,rules and regulation sometime lead to change some important procedures, some format etc.
2. Consumer  can given their feedbacks about  the existing systems  and want to change such by a new system.
3. unions like the union of truck divers want some type modification.
4. The market competitionarises suddenly and now it is essentially required to modigy or replace the exesting system to include new hardwares, software, technology etc.

Internal Sources

1. Organization itself wants to add some advanced techonology to modify the existing applications or to make    an improvement in it, like an organization acquires another organization.
2. Top management can also reuire the changes, like related to the cost.
3. User factors also sometimes require the change, like for any risk and potential returns.
4. Even the investigator himself (system analyst) may require it.

Feasibility Study: -

As a initial investigation is completed, it leads to a more detailed investigation of the system the conclusons of the initial study become the inputs for the detailed study feasibility study is called like because as in the first phase, we just check briefly about the problems related to the old system. Feasibility study can be defined as:-

Feasibility Study is test of a system proposal according to its workablity, impect on the organization, ablity to meet user needs , and effective use of resources. The task of this phase should clearly define:

1. The users demonstrable needs .
2. Availability of resources. 
3. Estimate the resources required.
4. Impact of the system.
5. Define and document in outline proposed system.

Friday, June 10, 2011

System Analysis

The basic objective of system analysis is to determine the feasibility of a system, and how it will meet the requirments of system users. Though in a typical system development life cycle, these activities among different teams having members with specialisation in different fields. A system analyst is an information system expert having intensive knowledge of computer hardware and software. His major functions are defining requirments, gathering data, analysing data, drawing up system specification, designing system, and testing system. System analysis involves the following aspects of system development :

1. Feasibility study
2. Requirment analysis
3. Structure analysis


Feasibility study : -

Feasibility study is the process of determining whether a system is appropriate in the context of organizational resources and constraints and meets the user requirments. The basic objectives of the feasible study are to identify whether the proposed system is feasible and will be more appropiate than the existing system, At this stage, the system development team defines the problems or opportunities, establishes feasibility study covers economit feasibility technical feasibilty, operational feasibility, and legal feasibility. There are many types of feasibility study : -

1. Economical feasibility : -

Economical feasibility involves determination of whether the given system is economically viable. it is done through cost/ benifit analysis to identify whether the benifits must be more than the cost.

2. Technical feasibility : -

Technical feasibility analyses whether the proposed system is technically viable with the available hardware, software and resources.

3. Operational feasibility : -

Operational feasibility, also known as behavioural feasibility, determines whether the proposed system will work effectively within the exisiting managerial and organisational frameworks. It is a comman phenomenon that computer installations have something to do with transfer, retraining and job status of employees.

4. Legal feasibility : -

Legal feasibility tries to ensure whether the new system meets the requirments of various information technology regulation , such as privacy laws, computer crimie law, malicious access to data, international law, etc.

STEP IN FEASIBILITY STUDY : -

1. Constitution of a project team
2. Identification of potential candidates systems
3. Identification of characteristics of candidates system
4. Performance and cost evaluation
5. Weighing system performance and cost data
6. Selection of the best system
7. Preparation of feasibility report

Requirment analysis : -

Requirment analysis is the most crucial stage of system analysis in which an analysis is done about who requires what information in what form and when. These three We are very important aspects because a system is meant for it s users and not for designer and operators. REquirment analysis define the scope of the system and the functions it is expected to perform. if the system is not designed according to information requirments, it will fail to achieve its objective inspite of choosing the best system. The system development team may use a variety of tools to identify the requirments-procedures and form used, on-site observation, interviews, questionnaires, and system used in other similar organizations.

1.Procedures and forms used : -

Every organisation uses certain procedures and forms i performing different functions. A procedure is a series of related tasks that make up the ohronological sequence and the established way of performing the work to be accomplished. If an organisation has adopted the policy of formalisation, various procedures are codified in a procedure manual. An organisation uses different types of forms for conducting its operation. Printed forms are widely used for capturing and providing information.

2. On-site observation : -

Another method of gethering information for analysis in on-site observation.
It is the process of recognising and nothing people. Object and occurrences to obtain information. The anlyst's role is that of information seeker and he is expected to be detached from the system being observed.

3. interview : -

information can be collected about the likely requirments through the personal interviews. interview is a formal, in-depth conservation conducted to gather information about how the present systems work and what modification are required in them. Interviews can be used for two main purposes-as an exploratory devise to identify relations or verify information and to capture information as it exist.

4. Questionnaires : -

A questionnaire is a formalised written schedule containing different question relevant to the object being studied. It obtains and records specified and relevant information with tolerable accuracy and completeness. A questionnaire can be directly administered by the analyst himself and gets the questionnaire filled himself on the basis of information provided by the respodent or can be adminisred indirectly by requesting the respondent to fill up the questionnaire.

5. System used in other organisation : -

When the organisation for which a system is being developed, does not have specific and methodological systems, information can be collected by studying the system of the similar nature. Information about such system can be gathered from professional journals, consulants, reports, and other publications.

Structured analysis : -

In analysing the present system and likely future requirments of the proposed system, the analyst collects a great deal od relatively unstructured data through procedure manuals, interviews, questionnaires, and other sources. The traditional apporach is to organise and convert the data through system flowcharts which support future development of the system and simplify communication with the users. Structured analysis has the following features :
1. Structured analysis is graphic that presents a picyure of what is being specified and is a conceptually easy-to-understand presentation of the application.
2.The process used in structured analysis is partitioned so that a clear picture of progression from general to specific in the system flow emerges.
3. Structured analysis is logical rather than physical. it specifies in a precise, consine, and highly readable manner the working of the system.
4. in structures analysis, certain tasks that are normally carried out late in the system development are undertaken at the analysis phase. For example, user procedures are documented during analysis rather than ins design or implementtation phase.

Wednesday, June 8, 2011

Motion Specification In Computer Animation

There are several ways in which the motions of objects can be specified in an animation system. We can define motion in very explicit tems, or We can use more abstract or more general approaches.

Direct motion specification : -

The most straightforward method for defining a motion sequence is direct specification of the motion paremeters. Here, We explicitly give the rotation angles and translation vectors. Then the geometric transformation matrices are applied to transform co-ordinate positions. Alternatively, We could use an approximating equation to specify certain kinds of motions. These methods can be used for simple user programmed animation sequencs.

Goal-directed systems : -

At the opposite extreme, We can specify the motions that are to take place in general terms that abstractly describe the actions. these systems are referred to as goal directed because they determine specific motion parameters given the goals of the animation. For example, We could specify that we want an object to "walk " or to "run" to a particular destination. Or We could state that we want an object to "pick up " some other specified object. The inpute directive are then interpreted in term of component motions that will accomplish the selected task. Human motion, for instance, can be defined as a heirarchical structure of sub motion for the toros, limbs,and so forth.

Kinematics and dynemics : -

We can also construct animation sequences using kinematic or dynemic descriptions. With a kinematic description, we specify the animation by giving motion parameters position, velocity, and acceleration) without reference to the forces that cause the motion. for constant velocity (zero acceleration), we designate the motions of rigid bodies in a scene by giving an initial position and velocity vector for each objects.

An alternate apporach is to use inverse kinematics. Here, we specify the initial and final positions of objects at specified times and the motion parameters are computed by the system . For example, assuming zero acceleration , we can determine the constant velocity that will accomplish the movement of an object from the initial position to the final position.

Dynamic descriptions on the other hand, require the specification of the forces that produce the velocities and acceleration. Descriptions of object behavior under the are generally referred to as a physically based modeling. Example of forces affecting object motion include electromagnetic, gravitational, friction, and other mechanical forces.

Object motion are obtained from the forces equations describing physical laws, such as newton's law of motion for gravitational ang friction processes, euler or navier-stokes equations describing fluid flow, and maxwell 's equations for electromagnetic forces. For example, the general form os newton's second law for a particle of mass m is
F = d(mv)/dt

with F as the force vector, and v as the velocity vector. If mass is constant, we solve the equation F=ma, where a is the acceleration vector. otherwise, mass is a function of time, as in relativistic motions of space vehicles that consume measurable amounts of fuel per unit time. We can also use inverse dynemics to obtain the forces, given the initial and final positions of objects and the type of motion.

Application of physically based modeling include complex rigid-body systems and such nonrigid systems as cloth and plastic materials. Typically, numerical methods are used to obtain the motion parameters incrementally from the dynemical equations using initial conditions or boundary values.

Tuesday, June 7, 2011

COMPUTER ANIMATION LANGUAGES

Languages:

Design and control of animation sequences are handled with a set of animation outlines.A general purpose language, such as c,lips,pascal,or fortran, is often used to program the animation functions, but several specialized animation languages have been developed. Animation functions include a graphics editor, a key frame generator, an in-between generator,and standard graphics routines. The graphics editor allows us to design and modify object shapes, using spline surface, constractive solid geometry methods, or other representation schemes.

A typical task in an animation specification is scene description.This includes the positioning of objects and light sources, defining the photometric parameters, and setting the camera parameters (position, orientation, and less characteristics). Another standard function is action specification. This involves the layout of motion paths for the object and camera. And we need the usual graphics routines: viewing and perspective transformations, geometric transformations to generate object movements as a function of accelerations or kinematic path specification, visible-surface identification, and the surface rendering operations.

key-frame systems are specialized animation languages designed simply to generate the in betweens from the user-specified key frames. Usually , each object in the scene is defined as a set of rigid bodies connected at the joints and with a limited number of degrees of freedom.

Parameterized systems allows object motion characterstics to be specified as part of the object definitions. The adjustable parameters control such object characteristics as degree of freedom, motion limitations, and allowable shape changes.

Scripting systems allows object specifications and animation sequences to be define with a user-input script. from the script, a library of various objects and motions can be constructed.

The Computer-Animation Process:

Half of the process of creating a computer-animated features films has nothing to do with computers. First, the filmmakers write a treatment, which is a roughly sketch of the stories. When they have settled on all of the story beats -- major plot points -- they are ready to create a storyboard of the films. The storyboard is a 2-D, comics-books-style rendering of each scene in the movie along with some jokes and snippets of important dialogues . During the storyboarding processes, the script is polished and the film makers can start to look how the scenes will work visually.

The next steps is to have the voice actors come in and records all of their lines. Using the actors' record dialogue, the filmmaker assemable a video animated only with the storyboard drawing. After further re-writing,editing, and re-recording of dialogues, the real animations are ready to begin.

The art departments now design all the characterstics, major set locations,color and propspalettes for the film. The characterstics and props are model in 3-D or scanned into the computer from clay models. Each character is equipped with hundreds of avars, little hinges that allow the animators to move specific parts of the characters body. Woody from 'Toy Story' for examples, had over 100 avars on his face alone.

The next steps is to create all of the 3-D set, painstakingly dressed with all of the detail that brings the virtual world to life. Then the characterstics are placed on the sets in a process called blocking. The director and lead animators block the key character position and camera angle for each and every shot of the movies.

Now team of animator is each assigned short snippet of scenes.They take the blocking instruction and create their own more detail key frame. They begin tweening process. The computer handle a lot of the interpolation -- calculating the best way to tween two key frame -- but the artist often has to tweak the result so they look even more lifelike.

Now the characterstics and props are given surface texture and colors. They are dressed with clothing that wrinkles and flow naturally with body movement, hair and fur that waves in the virtual breeze, and skin that look real enough to touch.

The final steps of the process are called rendering. Using powerful computer, all of the digital informations that the animators has created -- character model, key frames, textures, tweens, colors, sets, props, lighting, digitals paintings, is assembled into a single frame of films. Even with the incredible computing power of a companies. it take an average of six hours to render one frames of an animated films . That is over 88 years of rendering for a 90-minutes film.

Sunday, June 5, 2011

Computer Animation

What is Computer Animation ?

Computer animation follow the same formats by filming a sequence of painted cells then using more layers, keyframes, and tweening techniques. Layers provide the capabilities to place one image on top of another and to allows all or part of the under lying images show through. This capability allow you to maintained registration between multiple frames of animation and to look how various images in an animation go together.Registration are crucial concept in computer animation. Registration point let you know whether your layers are combined. When you work with Macromedia Freehand, Adobe Illustrator, or another programs that support to layers, you can copy and paste the registration points into every layer in the drawings so that points exactly overlap. On the computer, paint is most filled or drawn with tools using features such as gradients and anti-aliasing (soft gray edges that the make lines appear smooths). The word
inks, in computer animations terminology, usually means special methods for computing RGB (Red, Green, Blue) pixel values, providing edge detection, and layering so that images can blend or otherwise mix their colors to produce special transparency,inversions, and effects.

Computer animation generally refers to any time sequence of visual changes in a scene.In adddition to changig object position with translations or rotations , a computer - generated animatiion could diplay time variations in object size , color, transparency, or surface texture . Advertising animation often transiton one object shape into another for example, transformaing a can of motor oil into a automobile engien . computer animation can also be generated by changing camera parameters, such as position , orientation, and focal length. And we can produce computer animations by changing lighting effect or other parameter and procedures associated with illumination and rendering.Many applications of computer animation requried realistic display.

Design of Animation Sequences:

1. Storyboard layout
2. Object definition
3. Key - frame specifications
4. Generation of in- between frames

The storyboard is an outline of the action. It defines the montion sequence as a set of basic events that are to take place .Depending on the type of animation to be produeced , the storyboard could consist of a set of rough sketces or it could be a list of the basic ideas for the motion.

An object definition is given for each participant in the action . Object can be defined in terms of basic shapas, such as polygons or splines In addition , the associated movements for each object are specified along with shape.

A key frame are 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.Some key frames are chosen at extreme positions in the action; others are spaced so that the time interval between key frame is not too great.

In betweens are the intermeiate 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 .

General Computer Animation Functions:



Some steps in development of animation sequence are well - suited to computer solution . These include object manipulation and rendering camera motions, and the generation of in - betweens.
One function available in animation packages is provided to store and manage the object database. Object shapes and associated parameters are stores and updated in the database.Other object functions include those for motion generation and thosefor object renderingg. Motion can be generated according to specified constraints using two dimensional or three dimensional transformations.

Another typical function simulates cammera movements . Standard motions are zooming , panning , and tilting.

Friday, June 3, 2011

Computer Graphics Software

The graphics application interface code is the frist kind of software that requried to translate the parts of an object that understood by the computer system. These application programs used the subroutline or function to traslation , rotation, projection, Clipping and other operation that perform on the image. Initial it is very typical one application program developed image display on the other hardwere and application requried some changes.

Standard Software:

The standard software requried to provide flexibility or portability of graphics system. When any package used standard . Without standard , program designed to one hardware system can not be transfered to another system without rewriting the program.

Graphics kernel system :

The frist standard graphics software that adopted was GKS, This wasdeveloped intiallay 2D graphics.Further its 3D version,Frist its provide real protability of software among different hardware system second is that no other package provied the aility to write device independed graphics program.

PHIGS (Programmer's Hierarchical Interactive Standard):

This is the second software standard that was proved by standard orgnisation which is extension of GKS.as example- POPen_phigs(), Pclose_phigs() etc.

DXF file format:

Drawings Interchange Format (DXF) is one of most important grapics data exchange format. It is widely used in AUTO CAD drawing software's.DXF file is normally an ASCLL readable text file which consist of seven major sections: header,table , block, classes, object.end of file.

IGES file format:

The initial Graphic Exchange Specification (IDES) file format also use in CAD softwere charateristics of CAD data,annotation and orgnisation of data between various vector oriented application like CAD software , Reverse Engineering .

Intrgration of Graphics Standard:

- Application interface
- Device interface
- user Interface


There are standard available for these interface and connection between these are-

1. The standard for graphics programming (GKS,gksed,phigs)
2. The interface to the device driver and to the devices level graphics commends or command library.
3. Graphics level archive and interchange (CGM, CGI,VGI)
4. The data communication interface between different system or between a system and the commercial database being used (IGES,STEP ,etc)

Input Device :

Various type of input device available in the market that used in graphics workstation .

1. Stroke : the devices that returned the coordinate position (x,y) . As like of digitizer that return the (x,y) position on the click of button. A mouse , Joystick touch pad can be programmed to send the coordinate position.

2. Locator : All the devices that return coordinate position on the graphics display continuously as they move called locator devices as mouse. Joystick,3D mouse.

3. string : The device that input text to the CPU as like keyboard.

Thursday, June 2, 2011

Graphical Devices

Introduction:
The Graphics system are used to display picture with fast interactive response . so that it is basically needs two things first hardware and second software , hardware includes all type of hard ware as input. out and process. The standard input device that used in computer graphics system are as:
1. Alphanumeric Key Board.
2. Multimedia key board or programmed key
3. Mouse / Track Ball / Track space.
4. Scanner system (OCR,OMR,MICR,BCR)
5. Light pen
6. Digitizer
7. Joystick
8. Data Glove
9. Touch Screen
10. Voice System(microphone
11. Web Cam

Standard output devices as:
1. Monitor
2. Printer
3. Plotter
4. Sound System

Raster Scan Display :
To maintaining the picture display on the CRT screen use a special technique that called Raster scan display.
Horizontal retrace : When electron beam move across the row and one row to another row is called Horizontal retrace.
Vertical retrace: When electron beam move across the screen vertically and at last reach the bottom of the screen then electron beam set the top row of the screen this jump is called vertical retrace.

Color CRT Monitor :



A CRT monitor display color picture by using the combination of different type of phosphor that emit different type color light.
(1) Beam penetration method
(2) shadow mask method

(1) Beam penetration Method:
The Beam Penetration method displaying color picture has been used with random scan monitor.CRT screen coated by two layer of phosphor usually red and green.This method is very easy to implement but have some disadvantage it can display maximum color .

(2) shadow mask method
CRT screen coated the set of three dot of color phosphor respectively red . green 7 blue phosphor dot in triangular shape, It have three electron guns.


Composite CRT Monitor :



direct View Storage Tube (DVST)
Flat Panel display
Plasma Panel
Thin -Film electroluminescent display
LED display
Liquid Crystal display device