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We now turn our attention to operating on the point matrix G to produce the desired transformations. We will consider

  1. rotation
  2. scaling
  3. and translation (moving) of objects
. Rotation and scaling are done by matrix multiplication with a square transformation matrix A. If we call thetransformed point matrix G n e w , we have

[ G n e w ] = [ A ] [ G ] .

We call A a matrix operator because it “operates” on G through matrix multiplication. In contrast, translation must be done by matrix addition.

In a later section you will see that it is advantageous to perform all operations by matrix operators and that we can modify our image representation to allow translation to be done with a matrix operator like rotation andscaling. We will call the modified representation homogeneous coordinates .

Rotation. We saw in the chapter on linear algebra that the matrix that rotates points by an angle θ is

A = R ( θ ) = c o s θ - s i n θ s i n θ c o s θ .

When applied to the point matrix G , this matrix operator rotates each point by the angle θ , regardless of the number of points.

We can use the rotation matrix to do the single point rotation of the example from "Vector Graphics: Introduction" . We have a point matrix consisting of only the point ( 3 , 1 ) :

G = 3 1 .

The necessary transformation matrix is R ( θ ) with θ = π 6 Then the rotated point is given by

G n e w = R ( π 6 ) G = c o s ( π 6 ) - s i n ( π 6 ) s i n ( π 6 ) c o s ( π 6 ) 3 1 2 . 10 2 . 37 ·

Scaling. An object can be enlarged or reduced in each dimension inde- pendently. The matrix operator that scales an image by a factor of s x along the x-axis and s y along the y-axis is

A = S ( s x , s y ) = s x 0 0 s y .

Most often we take s x = s y to scale an image by the same amount in both dimensions.

Translation. An object can be moved by adding a constant vector b to every point in the object. For example, b = 20 - 5 will move an object 20 units to the right and 5 units down. We can write this in terms of the point matrix as

G n e w = G + b 1 T

where 1 (read “the one-vector”) is a vector of n l's:

1 = 1 1 1 .

In MATLAB, 1 may be obtained by. The outer product of b with 1 in Equation 7 simply serves to make n copies of b so that one copy can be added to each point in G . ones(n,1)

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
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Cied
what is biological synthesis of nanoparticles
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how did you get the value of 2000N.What calculations are needed to arrive at it
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Source:  OpenStax, A first course in electrical and computer engineering. OpenStax CNX. Sep 14, 2009 Download for free at http://cnx.org/content/col10685/1.2
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