# I want to create random bumps on a flat surface

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Daniel Gray on 17 Jul 2017
Commented: AMERA ANJUM on 23 May 2020
I have a 300x300 zeros matrix and I would like to create random bumps on the surface on random heights. To be more detailed, imagine circles of ones on the surface, I would like to (rather than those) have bumps on the surface.
Almost like 3D Guassian bumps on the surface.
Any help would be appreciated.

Grzegorz Knor on 17 Jul 2017
You can add Two-dimensional Gaussian functions with random amplitude at random location:
M = zeros(300,300); % initial matrix
N = 3; % number of bumps
sigma = 3;% std (width) of Gauss
maxAmplitude = 5; % maximum height
[x,y] = meshgrid(1:size(M,1),1:size(M,2));
for k=1:N
% random location of bumps
xc = randi(size(M,1));
yc = randi(size(M,2));
% Gauss function
exponent = ((x-xc).^2 + (y-yc).^2)./(2*sigma^2);
amplitude = rand()*maxAmplitude;
% add Gauss to the matrix M
M = M + amplitude*exp(-exponent);
end
surf(M)
##### 2 CommentsShowHide 1 older comment
AMERA ANJUM on 23 May 2020
Daniel Sir
On generation of random bumps at random locations of random amplitudes on the flat surface, do shrinkage of the flat surface area from the edges can be seen. So that over all area on bumping and debumping remains to be same. Please do reply