Generate a sector mask within a big matrix

A sector mask is defined by distance and angle. Please see the image for clarification on mask.

I want to generate a 100 by 100 matrix where all the matrix element inside the mask is 1 otherwise 0.

Thanks.

[Looky]

Do you already have the coordinates as show in the image? Then just convert to polar using cart2pol and afterwards use some simple logic to check for radius and the angle.

[Turlough Hughes]

Can you attach the matrix as a .mat

Answer 1

[Looky]

Solution could look like this:

% Generate example coordinates
x=linspace(-1,1,100);
y=fliplr(linspace(-1,1,100));
[X,Y]=meshgrid(x,y);

% Parameters for sector
angle=10;
radiusIn=.8;
radiusOut=.2;

% Coordinates to polarcoordinates
[phi, rho]=cart2pol(X,Y);
phi=rad2deg(phi);
phi(phi<0)=-phi(phi<0);

% Generate mask
mask=rho>radiusOut & rho<radiusIn & phi>angle& phi<180-angle;

% Have a look at the mask
spy(mask);

For your problem you should exchange the first part of generating the X and Y values for your own coordinates. Otherwise the mask might not be centered the way your data is.

[Ankit Labh]

Dear Looky,

Many thanks for your answer. It worked. I got many new ideas for other questions.

best regards,

Ankit