How can I generate data points form arbitrary shape in 2D in MATLAB ?

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Ammar 2016-12-1

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回答： Walter Roberson 2017-1-14

Dear All, I would like to ask: How can I generate data points form arbitrary shape in 2D in MATLAB ?

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Answer 1

Image Analyst 2016-12-1

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在 MATLAB Online 中打开

How about rand()?

numberOfVertices = 15;
x = rand(1, numberOfVertices);
y = rand(1, numberOfVertices);

If you want an image, use

binaryImage = poly2mask(x, y, rows, columns);

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Image Analyst 2016-12-1

在 MATLAB Online 中打开

Not that I know of. Perhaps if you were able to read a font file. In the meantime, here's some code that will create a heart shape:

t = linspace(-pi,pi, 350);
X =       t .* sin(pi * .872*sin(t)./t);
Y = -abs(t) .* cos(pi *      sin(t)./t);
plot(X,Y);
fill(X, Y, 'r');
axis square;
set(gcf, 'Position', get(0,'Screensize')); 
title('Happy Valentines Day', 'FontSize', 28);

There is also code to create a Batman logo: http://www.mathworks.com/matlabcentral/answers/13131-batman-equation-in-matlab#answer_17935 But nothing for a letter B I'm afraid. Sorry.

Ammar 2016-12-2

Dear Image Analyst, thank you very very much for your help. I found something in the Internet as well to generate the data points and when plot the data points give me concave shape. Please, could you look at this code and modify it to give letter B. i.e. generate data points and when I plot those data points give me the shape letter B. Regards.

C1 = [0 0]; % center of the circle C2 = [-5 7.5]; R1 = [8 10]; % range of radii R2 = [8 10]; A1 = [1 3]*pi/2; % [rad] range of allowed angles A2 = [-1 1]*pi/2;

nPoints = 1000;

urand = @(nPoints,limits)(limits(1) + rand(nPoints,1)*diff(limits)); randomCircle = @(n,r,a)(pol2cart(urand(n,a),urand(n,r)));

[P1x,P1y] = randomCircle(nPoints,R1,A1); P1x = P1x + C1(1); P1y = P1y + C1(2);

[P2x,P2y] = randomCircle(nPoints,R2,A2); P2x = P2x + C2(1); P2y = P2y + C2(2);

x=[P1x P1y]; y=[P2x P2y]; Data4=[x; y]; plot(Data4(:,1),Data4(:,2),'.')

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Answer 2

Image Analyst 2016-12-1

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Do you want the boundary points of a binary image shape? If so, use bwboundaries().

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Ammar 2016-12-1

Dear Image Analyst, I would like to thank you for this answer. Please, I am looking for data points when I plot them give me arbitrary shape. For example, shape like star or curve or Shape of letter B. I need the real data points give me those figures. Regards

Image Analyst 2017-1-14

And where do you think those real data points will come from if you don't have them already? Apparently you didn't think they can come from images of shapes as I suggested. So exactly where are you going to get those boundary points?

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