CG 2 MARKCG 2 MARKS.docS

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MC1704 Computer Graphics and Multimedia System

2 Marks Questions

1. What is scan conversion

A major task of the display processor is digitizing a picture definition given in an application

program into a set of pixel-intensity values for storage in the frame buffer. This digitizationprocess is called scan conversion.

2. Write the properties o! video display devices

Properties of video display devices are persistence, resolution, and aspect ratio.

". What is rasteri#ation

The process of determining the appropriate pixels for representing picture or graphics object isknon as rasterization.

4. $e!ine Computer %raphics.

!omputer graphics remains one of the most existing and rapidly groing computer fields.!omputer graphics may be defined as a pictorial representation or graphical representation of

objects in a computer.

&. 'ame any !our input devices.

"our input devices are keyboard, mouse, image scanners, and trackball.

(. Write the t)o techni*ues !or producin% color displays )ith a C+,

#eam penetration method, shado mask method

7. What is vertical retrace o! the electron -eam

$n raster scan display, at the end of one frame, the electron beam returns to the left top corner ofthe screen to start the next frame, is called vertical retrace of the electron beam.

. Short notes on video controller

%ideo controller is used to control the operation of the display device. A fixed area of the systemis reserved for the frame buffer, and the video controller is given direct access to the frame buffer

memory.

/. What is -itmap

&ome system has only one bit per pixel' the frame buffer is often referred to as

bitmap.

10. $i!!erentiate plasma panel display and thin !ilm electro luminescent display

$n plasma panel display, the region beteen to glass plates is filled ith neon gas. $n thin film

electro luminescent display, the region beteen to glasses plates are filled ith phosphor, suchas zinc sulphide doped ith manganese.

11. What is resolution

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The maximum number of points that can be displayed ithout overlap on a !)T is referred to as

the resolution.

12. What is hori#ontal retrace o! the electron -eam

$n raster scan display, the electron beam return to the left of the screen after refreshing each scan

line, is called horizontal retrace of the electron beam.

1". What is !ilament

$n the !)T, heat is applied to the cathode by directing a current through a coil of ire, is calledfilament.

14. What is pimap

&ome system has multiple bits per pixel, the frame buffer is often referred to as pixmap.

1&. Write the types o! clippin%

Point clipping, line clipping, area clipping, text clipping and curve clipping.

1(. What is meant -y scan code

*hen a key is pressed on the keyboard, the keyboard controller places a code carry to the keypressed into a part of the memory called as the keyboard buffer. This code is called as the scan

code.

17. ist out the merits and demerits o! enetration techni*ues

The merits and demerits of the Penetration techni+ues are as follos

$t is an inexpensive techni+ue

$t has only four colors The +uality of the picture is not good hen it is compared to other techni+ues

$t can display color scans in monitors

Poor limitation etc.

1. ist out the merits and demerits o! $3S,

The merits and demerits of direct vie storage tubes %&T/ are as follos $t has a flat screen

)efreshing of screen is not re+uired

&elective or part erasing of screen is not possible

$t has poor contrastPerformance is inferior to the refresh !)T.

1/. What do you mean -y emissive and nonemissive displays

The emissive display converts electrical energy into light energy. The plasma panels, thin film

electro-luminescent displays are the examples. The 0on-emissive are optical effects to convert

the sunlight or light from any other source to graphic form. 1i+uid crystal display is an example.

20. ist out the merits and demerits o! lasma panel display

2erits

)efreshing is not re+uired

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Produce a very steady image free of "licker

1ess bulky than a !)T.

emerits Poor resolution of up to 45 d.p.i

$t re+uires complex addressing and iring

$t is costlier than !)T.

21. What is persistence

The time it takes the emitted light from the screen to decay one tenth of its original intensity iscalled as persistence.

22. What is 5spect ratio

The ratio of vertical points to the horizontal points necessary to produce length of lines in bothdirections of the screen is called the Aspect ratio. 6sually the aspect ratio is 7.

2". What is the di!!erence -et)een impact and nonimpact printers

$mpact printer press formed character faces against an inked ribbon on to the paper. A line printerand dot-matrix printer are examples. 0on-impact printer and plotters use 1aser techni+ues, inkjet

sprays, 8erographic process, electrostatic methods and electro thermal methods to get imagesonto the papers. 9xamples are: $nkjet;1aser printers.

24. $e!ine piel

Pixel is shortened forms of picture element. 9ach screen point is referred to as pixel or pel.

2&. What is !rame -u!!er

Picture definition is stored in a memory area called frame buffer or refresh buffer.

2(. Where the video controller is used

A special purpose processor, hich is used to control the operation of the display device, isknon as video controller or display controller.

27. What is run len%th encodin%

)un length encoding is a compression techni+ue used to store the intensity values in the frame

buffer, hich stores each scan line as a set of integer pairs. x, y?.

2/. Write short notes on lines

A line is of infinite extent can be defined by an angle of slope + and one point on the line

P@P>x,y?. This can also be defined as y@mx! here ! is the Bintercept. C5. efine !ircleD

!ircle is defined by its center xc, yc and its radius in user coordinate units. The e+uation of the

circle is >x-xc? >y-yc? @ r3.

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"1. What are the various attri-utes o! a line

The line type, idth and color are the attributes of the line. The line type include solid line,

dashed lines, and dotted lines.

"2. What is antialiasin%

The process of adjusting intensities of the pixels along the line to minimize the effect of aliasingis called antialiasing.

"". What is ,rans!ormation

Transformation is the process of introducing changes in the shape size and orientation of the

object using scaling rotation reflection shearing = translation etc.

"4. What is translation

Translation is the process of changing the position of an object in a straight-line path from one

coordinate location to another. 9very point >x , y? in the object must under go a displacement to

>xE,yE?. the transformation is: xE @ x tx ' yE @ yty

"&. What is rotation

A 3- rotation is done by repositioning the coordinates along a circular path, in the x-y plane bymaking an angle ith the axes. The transformation is given by: 8E @ r cos >+ f? and BE @ r sin >+

f?.

"(. What is scalin%

A 3- rotation is done by repositioning the coordinates along a circular path, in the x-y plane by

making an angle ith the axes. The transformation is given by: 8E @ r cos >+ f? and BE @ r sin >+

f?.

"7. What is shearin%

The shearing transformation actually slants the object along the 8 direction or the B direction as

re+uired. ie' this transformation slants the shape of an object along a re+uired plane.

". What is re!lection

The reflection is actually the transformation that produces a mirror image of an object. "or thisuse some angles and lines of reflection.

"/. What are the t)o classi!ications o! shear trans!ormation

8 shear, y shear.

41. 'ame any three !ont editin% tools.

)es9dit, "


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A portion of a picture that is to be displayed by a indo is knon as indo port. The display

area of the part selected or the form in hich the selected part is vieed is knon as vie port.

44. $e!ine clippin%

!lipping is the method of cutting a graphics display to neatly fit a predefined graphics region or

the vie port

4&. What is the need o! homo%eneous coordinates

To perform more than one transformation at a time, use homogeneous coordinates or matrixes.They reduce unanted calculations intermediate steps saves time and memory and produce a

se+uence of transformations.

4(. $istin%uish -et)een uni!orm scalin% and di!!erential scalin%

*hen the scaling factors sx and sy are assigned to the same value, a uniform scaling is produced

that maintains relative object proportions. 6ne+ual values for sx and sy result in a differential

scaling that is often used in design application.

47. What is !ied point scalin%

The location of a scaled object can be controlled by a position called the fixed point that is toremain unchanged after the scaling transformation.

4. What is e#ier asis 8unction

#ezier #asis functions are a set of polynomials, hich can be used instead of the primitive

polynomial basis, and have some useful properties for interactive curve design.

4/. What is sur!ace patch

A single surface element can be defined as the surface traced out as to parameters >u, v? take all

possible values beteen 5 and ( in a to-parameter representation. &uch a single surface element

is knon as a surface patch.

&0. $e!ine Spline curve

A #-&pline curve is a set of pieceise>usually cubic? polynomial segments that pass close to aset of control points. Goever the curve does not pass through these control points, it only passes

close to them.

&1. What is a spline

To produce a smooth curve through a designed set of points, a flexible strip called spline is used.

&uch a spline curve can be mathematically described ith a pieceise cubic polynomial function

hose first and second derivatives are continuous across various curve section.

&2. What are the di!!erent )ays o! speci!yin% spline curve

6sing a set of boundary conditions that are imposed on the spline. 6sing the state matrix that characteristics the spline

6sing a set of blending functions that calculate the positions along thecurve path by specifying

combination of geometric constraints on the curve

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&". What are the important properties o! e#ier Curve

$t needs only four control points

$t alays passes through the first and last control points The curve lies entirely ithin the convex half formed by four control points.

&4. $e!ine ro9ectionThe process of displaying C into a 3 display unit is knon as projection. The projection

transforms C objects into a 3 projection plane

&&. What are the steps involved in "$ trans!ormation

2odeling Transformation

%ieing Transformation

Projection Transformation*orkstation Transformation

&(. What do you mean -y vie) plane

A vie plane is nothing but the film plane in camera hich is positioned and oriented for aparticular shot of the scene.

&7. $e!ine pro9ection

The process of converting the description of objects from orld coordinates to vieing

coordinates is knon as projection

&. What you mean -y parallel pro9ection

Parallel projection is one in hich z coordinates is discarded and parallel lines from each vertex

on the object are extended until they intersect the vie plane.

&/. What do you mean -y erspective pro9ection

Perspective projection is one in hich the lines of projection are not parallel. $nstead, they allconverge at a single point called the center of projection.

(0. What is ro9ection re!erence point

$n Perspective projection, the lines of projection are not parallel. $nstead, they all converge at a

single point called Projection reference point.

(1. $e!ine computer %raphics animation

!omputer graphics animation is the use of computer graphics e+uipment here the graphics

output presentation dynamically changes in real time. This is often also called real time

animation.

(2. What is t)eenin%

$t is the process, hich is applicable to animation objects defined by a se+uence of points, andthat change shape from frame to frame.

(". $e!ine !rame


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(4. What is key !rame


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72. What are the main !unctions o! a multimedia development system

2ultimedia development system must perform main three functions as

follos:K $nput data

K evelopment

K ata outputata input from sources such as cameras or musical instruments,

application development, and data output to some delivery medium such as a

videodisk or !-)iii? Amplitude

i< Wave!orm

&ound is produced by the vibration of matter. uring the vibration pressure variation are created

in the air surrounding it. The pattern of the oscillation is called a aveform.

;ii< 8re*uency

The fre+uency of the sound is the reciprocal value of the period. $t represents the number of

period s in a second and it is measured in Gertz >Gz? or cycles per second.

;iii< 5mplitude

A sound also has amplitude. The amplitude of a sound is a measure of the displacement of the air

pressure ave from its, or +uiescent state.

7(. $e!ine *uanti#ation ;or< resolution

The resolution >or? +uantization of a sample value depends on the number of bits used inmeasuring the height of the aveform. An I-bit +uantization yields 3H4 possible values, (4-bit

!-+udra +uantization results in over 4HHC4 values.

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77. What are the types o! sound o-9ects that can -e used in multimedia production

There are four types of sound objects that can be used in multimedia production:

K *aveform audioK 2$$ sound tracks

K !ompact disc >!? audio

K 2PC files

7. What is M?$?

2usical $nstrument igital $nterface >2$$? is the interface beteen electronic musicalinstruments and computers is a small piece of e+uipment that plugs directly into the computerNs

serial port and allos the transmission of music signal. 2$$ is considered to be the most

compact interface that allos full-scale output.

7/. ist out the components o! M?$? inter!ace.

A 2$$ interface has to different components:

K Gardare

K ata format

@ard)are connects the e+uipment. $t specifies the physical connection beteen musicalinstruments, stimulate that a port 2$$ port is built into an instrument, specifies a 2$$ cable

and deals ith electronic signals t that are sent over the cable.

$ata !ormat encodes the information traveling through the hardare 2$$ data format includes

an instrument Oconnected data format. The encoding includes, besides the instrument

specification, the notion of the beginning and end of a note, basic fre+uency and sound volume'

2$$ data allo an encoding of about (5 octaves, hich corresponds to (3I notes.

0. $e!ine the term !licker in video.

A periodic fluctuation of brightness perception is called flicker effect.

1. $e!ine +andom scanA+aster scan displays

)andom scan is a method in hich the display is made by the electronic beam, hich is directed,only to the points or part of the screen here the picture is to be dran. The )aster scan system

is a scanning techni+ue in hich the electrons seep from top to bottom and from left to right.

The intensity is turned on or off to light and sunlight the pixel.

2. What is an MC

The 2P! computer is not a hardare unit but rather a standard that includes minimum

specifications to turn $ntel microprocessor-based computers into multimedia computers.

". ist all the MC standards

There are currently three 2P! standards as follosK 2P! 1evel (

K 2P! 1evel 3

K 2P! 1evel C


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The standards apply not only to desktop computers but also to increasingly more poerful

multimedia laptops.

4. What is con!i%uration o! MC level 1 standards

The 2P! level ( minimum standard orkstation consisted of a (42Gz CI4&8 microprocessor,

atleast 32# of )A2, a C52# Gard disk, a !-)(4 colors?, an I-bitaudio board, speakers and;or headphones, and 2icrosoft indos softare ith the 2ultimedia

9xtensions package.

&. Write the con!i%uration o! MC level 2 standards.

2P! level 3 minimum standard consisted of a 3H2Gz FI4&8 microprocessor ith atleast F2#

of )A2, a C.H-inch high density, a (45 2# or larger hard disk drive, and a !-)4Fk? colors.

(. ist out the input devices o! multimedia.$nput devices for a multimedia system are as follos:

K MeyboardsK 2ouse

K Trackball

K Touch screenK 2agnetic card 9ncoders and )eaders

K Jraphics Tablets

K &canners

K

K igital cameras

7. What is a 3ideo disk

%ideo disk serves as the output of motion pictures and audio. The data are stored in an analog-

coded format on the disk. The reproduced data meet the highest +uality re+uirements. %ideo diskhas a diameter of approximately C5cm and stores approximately 3.4 Jiga bytes.

. What is synchroni#ation

$ntegration of the different media is given through a close relation beteen information units.This is called synchronization.

/. What is meant -y Multimedia Bser ?nter!ace

2ultimedia user interface is a computer interface that communicates ith users multiple media.

5. efine the folloing terms:

>i? !ompression )atio >ii? $mage Quality

;i< Compression +atio: The !ompression )atio represents the size of the original image divided

by the size of the compressed image.

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;ii< ?ma%e Quality: !ompression ratio typically affects picture +uality, the higher the

compression ratio, the loer the +uality of the decompressed image.

/1. What are the hi%her levels o! multimedia communication system ;MCS!&!*?.

/". ist out the tools !or colla-orative computin%The tools used for collaborative computing are as follos:

9lectronic mail #ulletin boards>e.g. 6senet nes?

&creen sharing tools>e.g. sho me from sunsoft?

Text-based conferencing systems >e.g. $nternet relay chat, !ompu&erve, America online?. Telephone conference systems.

!onference rooms>e.g. video indo from #ellcore?

%ideo conference systems>e.g.,2bone tools?

/4. What is %roup communication ;GCJ!? involves the communication of multiple users in a synchronous or

an asynchronous mode ith centralized or distributed control.

/&. What are the consistent o! a %roup communication

Jroup communication architecture consists of the folloing: &upport model

&ystem model

$nterface model

The J! support model includes group communication agents that communicate via a multi-pointmulti-cast communication netork.

/(. $e!ine the term Group +ende#vous

Jroup rendezvous denotes a method, hich allos one to organize meetings and to get

information about the group, ongoing meetings and other static and dynamic information.

/7. ist out some eamples !or inter!ace model protocols.

&ynchronous rendezvous methods use:

irectory services

9xplicit invitations

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irectory services access information stored in a knoledge base about the conference, such as

the name of the conference, registered participants, authorized users and name and role of the

participants

/. What are the advanta%es and disadvanta%es o! replicated architecture

The advantages of replicated architecture are: 1o netork traffic

1o response times

1o netork traffic is because only input events are distributor among the sites and loresponse times, since all participants get their output from local copies of the application.

The disadvantages are the re+uirement of the same execution environment for the application of

each site, and the difficulty in maintaining consistency.

//. What are the advanta%es and disadvanta%es o! centrali#ed con!erence control

The advantage of the centralized conference control is guaranteed consistency of the conference

state. The disadvantage is that hen a ne participant >outside of the invited group? ants tojoin, explicit exchange of the conference state must be performed among all participants, hich

causes large delays.

100. What are the advanta%es o! distri-uted con!erence control

Advantages of distributed conference control are:

$nherent fault tolerance-$f a netork connection breaks don in the middle of a conference and

it is repaired, it is easier to re-establish the shared conference state since there is no strict

consistency re+uirement.

&caling properties-At some point refresh periodicity needs to adapt to the size and scope of the

conference, otherise, the conference may be in danger of flooding itself ith session reports.

101. What is a session mana%er

&ession management architecture is built around an entity session manager, hich separates thecontrol from the transport. #y creating a reusable session manager, hich is separated from the

user interface, conference oriented tools avoid a duplication of their effort.

102. ist the various !unctionalities o! session mana%er

&ession manager includes local and remote functionalities. 1ocal functionalities include:

2embership control management

"loor control 2edia control management

!onfiguration management

!onference control management

10". What are the contents o! synchroni#ation

&ynchronization in multimedia systems comprises of content, spatial and temporal relations

beteen media objects.

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104. What is presentation re*uirement

Presentation re+uirements consist of intra-object synchronization, the accuracy concerning

delays in the presentation of 16s and, for inter-object synchronization, the accuracy in theparallel presentation of media objects.

art ;1( marks Questions8o,Bo?3? 1oad >8o,Bo? in to the frame buffer

ie? Plot in the first pointC? !alculate constants Kx, Ky, 3Ky, 3Ky - 3Kx and obtain the starting value

for the decision parameter as

Po @ 3Ky O KxF? At each 8k along the line, starting at k@5 perform the folloing test

ie? $f PM R 5 the next point to plot is 8k ( , Bkand

Pk( @ Pk 3Ky

8k(, Bk(? and Pk( @ Pk 3Ky-3Kx

H? )epeat step F Kx times

9xample8(@H

B(@(5

83@(5B3@35

dx @H

dy@(5

P @ 3Sdy O dx @ 3S(5 O H @ 35 O H @ (H$ncrements for the successive decision parameter is

3dy@3S(5@35

3dy - 3dx @ 3 S (5 O 3 S H @35 O (5 @(5$f H (5 >false?

8@H

B@(58end @(5

&etpixel>H,(5?

*hile H R (5

8@4

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$f >(HR5? then > false?

P @ 3dydx

B@(5( @((P@ (5 3 S >(H-(5? @ (5(5@35

&etpixel > 4, ((?

9tcU.

Procedure

Procedure linebres>xa , ya ,xb ,yb : integer?%ar

dx, dy, x, y, x9nd, p : integer '

begin

dx :@ abs>xa O xb? 'dy :@ abs>ya O yb? '

p :@ 3S dy O dx '

if xa xb then

be ginx :@ xb '

y :@ yb 'x9nd :@ xa'

end

elsebegin

x :@ xa '

y :@ ya '

x9nd :@ xb'end

setpixel > x, y, (?'

*hile x R x9nd do#egin

x :@ x ( '

if p R 5 then p :@ p 3 S dy'else

#egin

y :@ y('

p :@ p 3 S >dy O dx ?'9nd

&etpixel >x, y, (?'

9nd9nd >1ine #res?

". $e!ine Clippin%. Write and eplain Cohen E Sutherland line clippin% al%orithm.

A Procedure that identifies those portions of a picture that are either inside or outside of a

specified region of space is referred to as a !lipping $n this method processing of line segments

by performing initial tests that reduce the number of intersections that must be calculated. 9very

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line endpoint in a picture is assigned a four-digit binary code , called region code that identifies

the location of the point relative to the boundaries of the clipping rectangle. )egions are setup in

reference to the boundaries . 9ach bit position in the region code is used to indicate one of thefour relative coordinate positions of the point ith respect to the clip indo: to the left ,right,

top or bottom. #y numbering the bit positions in the region code as ( through F from right to left,

the coordinate regions can be correlated ith the bit positions arebit ( : left

bit 3 : right

bit C : belobit F : above

pic

A value of ( in any bit position indicates that the point is in relative position' x,y? to

the clip boundaries. Pic.#it ( is set to ( if x R xmin . The other three bit values are determined using similar

comparisions.)egion code bit values can be determined ith folloing 3 steps

(? !alculate differences beteen endpoint coordinates and clipping boundaries.

3? 6se the resultant sign bit of each difference calculation to set the corresponding value in theregion code.

#it ( is the sign bit of x-xmin

#it 3 xmax O x

#it C y O ymin#it F ymax O y Pic?

$ntersection points ith a clipping boundary can be calculated nusing the slope intercept form of

the line e+uation . for a line ith endpoint coordinates >x( , y(? and > x3, y3? the y coordinate ofthe intersection point ith a vertical boundary can be obtained ith the calculation y @ y( m>x-

x(? here x value is set either to xmin or to xmax and the slope of the line is calculated as

m @ >y3 O y(? ; > x3 O x(?similarly ,the x coordinate can be calculated as

x @ x( > y-y(?;m

ith y set either to ymin to ymax Algorithm for line clipping for cohen &utherland line

clipping method.

F. plain +e!lection and shearin%.

A reflection is a transformation that produces a mirror image of an object. The mirror image for ato dimensional reflection is generated relative to an axis of reflection by rotating the object

(I55 about the reflection axis. *e can choose an axis of reflection in the xy plane or

perpendicular to xy plane. *hen the reflection axis is a line in the xy plane, the rotation pathabout this axis is in a plane perpendicular to the xy plane, the rotation path is in the xy plane. Pic.

)eflection about the line y @ 5 , the x axis, is accomplished ith the transformation

matrix

( 5 5

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5 -( 5

5 5 (

picA reflection about the y axis flips x coordinates hile keeping y coordinates the same. The

matrix for this transformation is

-( 5 55 ( 5

5 5 (

pic*e flip both the x and y coordinates of a point by reflecting relative to an axis that is

perpendicular to the xy plane and that passes through the coordinate origin. This transformation

has the matrix representation

-( 5 55 -( 5

5 5 (

pic

$f e choose the reflection axis as a diagonal line y @ x the reflection matrix is5 ( 5

( 5 55 5 (

pic

To obtain a transformation matrix for reflection about the diagonal y @ -x *e could concatenatethe matrices for the transformation se+uence

(. !lockise rotation by FH5

3. reflection about y axis and

C. counter clockise rotation by FH5 the resulting transformation matrix is5 -( 5

-( 5 5

5 5 (&hearing

A transformation that distorts the shape of an object such that the transformed &hape appears as

if the object ere composed of internal layers that had been caused to slide over each other iscalled a shear.

pic

An x- direction shear relative to the x axis is produced ith the transformation matrix

( shx 55 ( 5

5 5 (

hich transforms coordinate positions asxN @ xshx

yN@y

An real number can be assigned to the shear parameter shx. A coordinate position >x,y? is thenshifted horizontally by an amount proportional to its distance > y value? from the x axis >y@5?

&etting shx to 3 for example, changes the s+uare into parallelogram.

Pic

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0egative values for shx shift coordinate positions to the left. *e can generate x O direction

shears relative to other reference lines ith

( shx -shx . yref5 ( 5

5 5 (

ith coordinate positions transformed asxN@ xshx>y-yref?

yN@ y

picA B direction shear relative to the line x@xref generated ith the transformation matrix

( 5 5

shy ( -shy . xref

5 5 (pic

hich generates transformed coordinate positions

xN@ x

yN@ shy>x-xref?yThis transformation shifts a coordinate position vertically by an an amount proportional

to its distance from the reference line x @ xref

&. plain asic ,rans!ormations )ith procedure

Transformation !hanges in orientation , size, and shape are accomplished ith geometricTransformations that alter the coordinate descriptions of the object The basic transformations are

a? Translation

b? )otation

c? &calingTranslation

A translation is applied to an object by repositioning it along a straight line path from one

coordinate location to another. *e translate a 3 dimensional point by adding translation distancestx and ty , to the original coordinate position >x, y? to move the point to a ne position >xN, yN?

xN @ x tx

yN @ y tyThe translation distance pair >tx, ty? is called translation vector or shift vector. *e can express

the translation e+uations as a single matrix e+uation by using column vectors to represent

coordinate positions and the translation vector

P @ x( PN @ x(N T @ txx3 x3N ty

Therefore PN @ P T

"ig)otation

A 3 dimensional rotation is applied to an object by repositioning it along a circular path in the xy

plane. To generate a rotation , e specify a rotation angle theta and the position >xr, yr? of therotation point about hich the object is to be rotated. *e first determine the transformation

e+uations for rotation of a point position P hen the pivot point is at coordinate origin. "ig

6sing the standard trigonometric identities , e can express the transformed coordinates in terms

of angles K and K is

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xN @ rcos>K K? @ rcos Kcos K O rsin K sin K

yN @ rsin >K K? @ rcosKsin K rsinKcos K ---------$

The original coordinates of the point in polar coordinates arex@ rcos K and y@ rsin K --------------------$$

&ubstituting the values of $$ to $ e obtain the transformation e+uations for rotating a

point at position >x,y? through an angle K about the originxN@ xcos K - ysin K

yN@xsin K - ycos K

Therefore,PN @ ) . P

&caling

&caling transformation alters the size of an object. This operation can be carried out for polygons

by multiplying the coordinate values > x, y? of each vertex by scaling factors sx and sy toproduce the transformed coordinates >xN, yN ?

xN @ x . sx

yN @ y.sy

&caling factor sx scales objects in the x direction, hich sy scales in the y direction.The matrix form of transformation is

xN @ sx 5 x5 sy . y

yN

PN @ & . P*hen sx and sy are assigned the same value,a uniform scaling is produced that maintains relative

object proportions. 6ne+ual values for sx and sy result in a differential scaling hat is often used

in design applications. *e can control the location of a scaled object by choosing a position ,

called the fixed point that is to remain unchanged after the scaling transformation.Pic

!oordinates for the fixed point >xf,yf? can be chosen as one of the vertices. "or a vertex ith

coordinates >x,y? the scaled coordinates >xN ,yN? are calculated asxN @ xf > x O xf ?sx

yN@ yf >y - yf? sy

*e can rerite these scaling transformations to separate the multiplicative and additive terms.xN@ x.sx xf>(-sx?

yN@ y.sy yf>(-sy?

here the additive terms xf>( O sx ? and yf> (- sy? are constant for all points in the object.

(. plain i< C$ ii< $

i? 1! >1i+uid !rystal isplay?6sed in T%, calculator, etc.

Produce picture by passing polarized light from the surrounding or from an internal light source

through a li+uid crystal materials. 1i+uid crystal refers the fact that these compounds have acrystalline arrangement of molecules . They flo like a li+uid. &o it called 1!. )e+uires to

glass plates. 9ach contains a light polarized at right angles to each other . )os of horizontal

transparent conductor contains one glass plate. !olumns of vertical transparent conductor

contains another glass plate. $ntersections of to defines a pixel position. 2olecules are aligned

(I


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on V1ight 9mitting iodes?A matrix of diodes are arranged to form the pixel positions to display. The pixture definition is

stored in refresh buffer Xust like scan line , it need data from the refresh buffer and convert into

voltage level depends upon the intensity value that are applied to diodes.

7. plain pro9ections in detail

Projection is mainly classified as

a. Parallel projection

b. Perspective projectionParallel projection

!o-ordinate positions are transformed to the vie along the parallel line. *e can specify aparallel projection ith a projection vector that defines the direction for the projection lines.


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The position of the point on Y axis is

Tan K @Y;1

1@z; Tan K @Y1(Perspective Projection

z-zprp?66 can have values from o to (

*hen 6 @ 5 , position P @ >x, y, z?

*hen 6 @ ( , Position P @ >5,5,Yprp?

. plain e#ier Curves in detail

#ezier curve uses spline approximation method and idely used in !A. This as developed by"rench 9ngineer Pierre #ezier

#ezier !urves

!urve section is approximated and their relative position determine the degree of polynomial#lending "unction specification is convenient

0( control points , Pk @ >xk, yk, zk? ith M "rom 5 to n. They can be blended to P>6?

hich describes path beteen P5 and Pu

P>6?@ Knk@5 Pk #9Y k,n>6?

#ezier blending functions #9Yk,n>6? are the #ernstein Polynomials

#9Yk,n>6? @ !>n,k? 6k >(-6? n-k*e can define #ezier #lending functions ith recursive calculation

#9Yk,n>6? @>(-6? #9Yk,n-( 6 #9Yk-(,n-(>6?

*ith #9Yk,k @ 6 k and #9Y5,k@>(-6?kThe curve lies ithin the convex hull. The blending functions are all positive and their sum is

alays (

!onvex )ule property ensures the polynomial smoothly follos the control point. !ubic #ezier

!urves. 2any graphics packages provide only cubic spline function. They are generated ithfour control points. "our blending functions for cubic #ezier !urve is obtained by putting n@C

#9Y5,C>6? @ >(-6?C

#9Y(,C>6? @ C6>(-6?3#9Y3,C>6? @ C63>(-6?

#9YC,C>6? @ 6C

Properties of #ezier !urvesAlays passes through the first and last control point

The boundary conditions at to ends are

P>5? @ Po

P>(? @Pn

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/. plain animation in detail

The term computer animation generally refers to any time se+uence of visual changes in a

sceneesign of animation se+uence

&teps are

(. &tory board layout3.


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can be set to 5 or to the largest value.

To buffers are necessary. A depth buffer is used to store depth values of each >x,y?

position and refresh buffer to store intensity for each position. $ntensity buffer is setto 5>min? and refresh buffer is initialized to background intensity.

The depth is calculated for each position . $f it is greater than value stored in depth

buffer, the ne value is stored.The Algorithm is

(. $nitialize the depth buffer = refresh buffer. &o that depth >x,y? @5 refresh >x,y?@(

3. "or each position on each polygon surface compare depth values to previouslystored values in the depth buffer to determine visibility.

!alculate the depth z for each >x, y? position on the polygon

$f Y R depth >x,y? then set depth >x,y? @ Y

refresh >x, y? @$surf >x, y?$ is the value for background intensity.

11. plain applications o! Computer %raphics

$mage Processing !omputer Aided esign >!A?

9ducation 9ntertainment

Jraphical 6ser $nterface >J6$?

2orphing Animation

%isual Programming

12. plain a. $epth Cuein% -. Sur!ace +enderin%

a.epth !ueing

A simple method for indicating depth ith ire frame displays is to vary the

intensity of objects according to their distance from the vieing position- 1ine closest to the vieing position are displayed ith highest intensities

- 1ines "arther - ecreasing $ntensities

6ses!hoosing maximum and minimum intensities

)ange of distances over hich the intensities are to vary

2odeling the effect of atmosphere

b. &urface )endering)ealism is attained by setting the surface intensity of objects according to

(. 1ighting conditions in the scene

- The intensity and positions of light sources- The general background illumination re+uired for a scene

3. Assigned surface characteristics

- egree of transparency- Go rough or ho smooth the surfaces to be.

-

1". plain "$ trans!ormations in detail

$nclusion of Y coordinates

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Translation

9xplanation

2atrix form)otation

9xplanation

2atrix "orm&caling

9xplanation

2atrix "orm

14. plain the classi!ication o! 3isi-le sur!ace $etection methods )ith eample.

#roadly classified in to 3 categories

i. x, y? position on the polygon

$f Y R depth >x,y? then set depth >x,y? @ Y

refresh >x, y? @$surf >x, y?

$ is the value for background intensity.

3C


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o Text 9diting = *ord Processing Tools

o Painting = raing Tools

o $mage O 9diting Toolso &ound 9diting Tools

o Animation, video = igital 2ovie Tools

2". What are the various input and output devices that can -e used in a

Multimedia C plain in detail.

$nput devices Meyboards

2ouse

Trackball

Touch screens 2agnetic card 9ncoders = )eaders

Jraphic tablets

"lat O bed scanner

Documents

CG 2 MARKCG 2 MARKS.docS