Set a specific spatial frequency for my Guassian generated dots

Hello! I am fairly new to Matab and I am stuggling with including a specific spatial frequency for my dot pattern.I need to generate polka dot patterns using either sine waves or gassian function with a specific satial frequency. I decided to use Gaussian funtion. In the code below, I am generating random dots using the Gaussian function. I need my dots to have a specific spatial frequency so that I can divide my pictures into low spatial frequncy and high spatial frequncy groups. But I am struggling to figure out how to do that. Any help/tips is much appreciated.

N=560;
nDots = 5;
s=25;

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

xc=rand(nDots,1)*N

xc = 5×1

59.3940 530.3383 143.4087 60.1356 545.9591

yc=rand(nDots,1)*N

yc = 5×1

96.8866 528.8498 375.8636 334.4373 52.0325

val=zeros(N)

val = 560×560

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

for k=1:nDots
    r2=(x-xc(k)).^2 + (y-yc(k)).^2;
    val = val + exp(-r2 / (2*s^2));
end
imagesc(val);
colormap gray;
axis equal;
axis off;

Answer 1

[Mathieu NOE]

hello

maybe this ?

now you can specify the x and y direction spacing with dx and dy (the total number of points is constant) . You can actually see that the picture gets bigger if you increase dx and dy

you may want to use the same value for both dx and dy for simplification

N=560;
nDots = 5;
s=25;

% spatial spacing
dx = 0.25;
dy = 0.5;
s=25*norm(dx,dy); % correct s for non unity spatial spacing

x1 = dx*(1:N);
y1 = dy*(1:N);
[X,Y]=meshgrid(x1,y1);
xc=rand(nDots,1)*N*dx;
yc=rand(nDots,1)*N*dy;
val1=zeros(N);
for k=1:nDots
    r2=(X-xc(k)).^2 + (Y-yc(k)).^2;
    val1 = val1 + exp(-r2 / (2*s^2));
end
figure(1);
imagesc(x1,y1,val1);
colormap gray;
axis equal;
% axis off;

[Gelareh]

Dear Mathieu

Thank you for your answer. I need all my dots to have a certain spatial frequnecy. By divinding my pictures to low and high satial frequency I meant the dots. Thanks!

[Mathieu NOE]

If my nswer has helped you, do you mean accepting it ?

thanks