How to Turn Imagesc to x and y?

Question

Sushmitha Kudari 2020-2-19

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https://ww2.mathworks.cn/matlabcentral/answers/506496-how-to-turn-imagesc-to-x-and-y

评论： Rik 2020-2-23

I have the following file MunkS_500Hz.shd.mat,

 munkProfile = load('MunkS_500Hz.shd.mat'); 
 pressureWave = munkProfile.pressure; 
 pressureWave = abs(pressureWave); 
 squished = squeeze(pressureWave);
 figure
 plot(squished);
 logged = log(squished) 
 imag = imagesc(logged);

that I can make into a 501 x 1001 matrix. Now I want to take this matrix from imagesc and put make it into a 3D point cloud. I would like some advice on how to do this. (I am unable to insert the file here even as a .zip file, I can email it to you if you think you can help).

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Answer 1

Rik 2020-2-19

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https://ww2.mathworks.cn/matlabcentral/answers/506496-how-to-turn-imagesc-to-x-and-y#answer_416423

编辑：Rik 2020-2-19

在 MATLAB Online 中打开

You can generate the coordinates with ndgrid and then you can linearize the three matrices and use them as input to plot3.

I=randi(255,501,1001);
[X,Y]=ndgrid(1:size(I,1),1:size(I,2));
plot3(X(:),Y(:),I(:),'.')

(untested code)

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Sushmitha Kudari 2020-2-22

I need to create a 3D point cloud of the logged = log(squished) . For this i need only its x and y components. So for example if this is my x and y:

X Y

1 1

1 8

2 8

5 6

2 5

I want to add a z-component to each so that I can plot it 3D space:

X Y Z

1 1 0

1 1 1

1 1 2

1 1 3

...

1 8 0

1 8 1

1 8 2

...

and so on

Rik 2020-2-23

If you don't treat the pixel value as the z value, how are you using your data at all?

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Answer 2

Sushmitha Kudari 2020-2-21

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https://ww2.mathworks.cn/matlabcentral/answers/506496-how-to-turn-imagesc-to-x-and-y#answer_416599

在 MATLAB Online 中打开

I am trying to replicate this model (without the animation) using x and y from the logged. I want to make a 360 degree point cloud model by replicating x and y on different x planes.

%%will plot the formation of ripples on water surface  ('_') ->
clear all 
clc
x=-50:0.5:50;
y=-50:0.5:50;
[X,Y] = meshgrid(x,y); % create rectangular mesh
R=sqrt(X.^2+Y.^2); %radius
k=0.1; % wave vector
phi=0; % phase
count=1;
for freqrps=0.1:0.1:2*pi
                    Z=sin((2*pi-freqrps)*k*R);
                   surf(X,Y,Z,'Facecolor','blue','Edgecolor','none');
                   axis equal;
camlight right  ; 
lighting phong;
 M(count)=getframe;
            count=count+1;
end