How can I create a surface with points distributed randomly ?

Hi

How can I create a surface with points distributed randomly like the attached file.

Best regards

[Walter Roberson]

See for example https://www.mathworks.com/matlabcentral/answers/22579-surface-plot#comment_690488

[Mallouli Marwa]

I search how can I create a plane with points not a 3d curve.

Answer 1

[Walter Roberson]

N = 25;
x = rand(1,N) * 150;   %wider than it is tall
y = rand(1,N) * 50;
pointsize = 20;
scatter(x, y, pointsize, 'filled')

[Mallouli Marwa]

Thanks

Answer 2

[Image Analyst]

Try scatteredInterpolant()

[Mallouli Marwa]

How can I simulate it ?

[Image Analyst]

Try this demo:

% Demo to show how scatteredInterpolant works to create a complete image out of arbitrarily placed sample points.
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;

numTrainingPoints = 50; % Number of points we'll have to try to estimate our image everywhere.
imageWidth = 300;
% Create sample surface
z = peaks(imageWidth);
[rows, columns] = size(z);
% Plot it as a flat image.
subplot(2, 2, 1);
imshow(z, []);
title('Original Image with Training Points in Red', 'FontSize', fontSize, 'Interpreter', 'None');
% Show it as a perspective 3-D-ish image.
subplot(2, 2, 3);
surf(z, 'EdgeColor', 'none');
title('Original Surface', 'FontSize', fontSize, 'Interpreter', 'None');

% Create sample coordinates
xi = imageWidth * rand(numTrainingPoints, 1);
yi = imageWidth * rand(numTrainingPoints, 1);
% Plot these over the image
subplot(2, 2, 1);
hold on;
plot(xi, yi, 'r.', 'MarkerSize', 15);
% Get z values.  For this demo, let's get them from the peaks image.  
% Then we'll try to recreate the peaks shape from the few points in x and y.
for k = 1 : length(xi)
	zi(k) = z(ceil(yi(k)), ceil(xi(k)));
end
zi = zi'; % Make zi a column vector like scatteredInterpolant requires.

%================================ MAIN PART RIGHT HERE ==============================================
% Make the scattered interpolant.
F = scatteredInterpolant(xi, yi, zi)

% Get a grid of points at every pixel location in the RGB image.
[xGrid, yGrid] = meshgrid(1:columns, 1:rows);
xq = xGrid(:);
yq = yGrid(:);

% Evaluate the interpolant at query locations (xq,yq).
vq = F(xq, yq);
fittedImage = reshape(vq, rows, columns);
%================================ END OF MAIN PART ==============================================

% Plot it as a flat image.
subplot(2, 2, 2);
imshow(fittedImage, []);
title('Interpolated Image with Training Points in Red', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
% Plot the training points over the image.
hold on;
plot(xi, yi, 'r.', 'MarkerSize', 15);

% Show it as a perspective 3-D-ish image.
subplot(2, 2, 4);
surf(fittedImage, 'EdgeColor', 'none');
title('Interpolated Surface', 'FontSize', fontSize, 'Interpreter', 'None');

%------------------------------------------------------------------------------
% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0, 0.04, 1, 0.96]);
% Get rid of tool bar and pulldown menus that are along top of figure.
% set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
set(gcf, 'Name', 'Demo by ImageAnalyst', 'NumberTitle', 'Off')