creating a circle in Matlab...

[luca.pa...@gmail.com]

Hi everyone,

I have a 128 X 128 matrix that represents an image.

What I want to do is create a filled circle in the matrix with the
center at a given point and of a given radius and filled with a given
value.

What is the easiest way to do something like this?

Cheers,
Luc

[Peter Boettcher]

luca.pa...@gmail.com writes:

Generate two matrices of coordinates x and y. Then operate on those
coordinates to produce whatever you want. In this case, calculate the
distance from your point. If that distance is < R, the point is inside
the circle. Etc.

[x y] = meshgrid(1:128, 1:128);

imagesc(x)
imagesc(sqrt(x.^2 + y.^2))
imagesc(sqrt((x-64).^2 + y.^2))

etc.

-Peter

[Vikas Mehta]

Peter Boettcher <boet...@ll.mit.edu> wrote in message
<muyabpg...@G99-Boettcher.llan.ll.mit.edu>...

hi,
i have the following matlab code to draw a circle. I want
to know how i can fill the circle with black.

t = linspace(0,2*pi,1000);
h=0;
k=0;
r=10;
x = r*cos(t)+h;
y = r*sin(t)+k;
plot(x,y);
axis square;

I also want to know how i can cut the circle in such a way
that the four quarters of the circle which are black in
color move to the corners.

Thanks,
Vikas

[Walter Roberson]

In article <fi27ip$2s3$1...@fred.mathworks.com>,
Vikas Mehta <gets...@yahoo.co.in> wrote:

>i have the following matlab code to draw a circle. I want
>to know how i can fill the circle with black.

>t = linspace(0,2*pi,1000);
>h=0;
>k=0;
>r=10;
>x = r*cos(t)+h;
>y = r*sin(t)+k;
>plot(x,y);
>axis square;

Instead of plot(x,y), fill(x,y,'k')
--
"Okay, buzzwords only. Two syllables, tops." -- Laurie Anderson

[RazvanStef...@gmail.com]

Hi!

In Matlab there is a function Delaunay to construct the Delaunay Graph
of a 2 dimension set of points. Does anyone have/know how to compute
the source code for drawing the Gabriel Graph using Matlab?

The Gabriel graph of a set P of points in the plane is defined as
follows: Two points p and q are connected by an edge of the Gabriel
graph if and only if the circle with diameter pq does not contain any
other point of P in its interior.

[someone]

luca.pa...@gmail.com wrote in message
<1195060087.6...@50g2000hsm.googlegroups.com>...

Believe it or not, you actually use the MATLAB rectangle
command to draw circles. The following code will draw a
circle of radius 3 centered at x=0 & y=0:

>> radius = 3;
>> w = radius;
>> h = radius;
>> x = 0;
>> y = 0;
>> rectangle('Position',[x,y,w,h],'Curvature',[1,1])
>>

[someone]

"someone " <som...@somewhere.net> wrote in message
<fm5l0a$rp4$1...@fred.mathworks.com>...

Oops... Forgot the last part of your question.

To fill the above circle with green, use:

rectangle('Position',[x,y,w,h],'Curvature',

[1,1],'FaceColor','g'))

[somayeh.she...@gmail.com]

hi- you said that " In this case, calculate the

distance from your point. If that distance is < R, the point is inside

the circle." i want to do like this but dont know how...:(