CODEWITHSUNDEEP
matlab
user2754278
user2754278

Reputation: 1

How to sort point cloud in matlab

I have the text file of point cloud data, for example

[17.42851 7.370431 -0.8465996                                            
17.3368 7.309645 -0.6999135
17.17311 7.201123 -0.4422026 
17.26928 7.269999 -0.5591076 
17.09828 7.153707 -0.3068624 
17.59379 7.476501 -0.8979237]

In above .txt file in first row first value indicates x coordinate, 2nd indicates y and 3rd indicates z coordinate. By using uiimport command in matlab , I imported it but the problem is, I want to plot these points layer by layer, so how should I separate it layer by layer? Please tell me the command from matlab.

Upvotes: 0

Views: 2234

Answers (2)

Robert Seifert
Robert Seifert

Reputation: 25232

your matrix:

A = [17.42851 7.370431 -0.8465996;                                            
17.3368 7.309645 -0.6999135;
17.17311 7.201123 -0.4422026; 
17.26928 7.269999 -0.5591076; 
17.09828 7.153707 -0.3068624; 
17.59379 7.476501 -0.8979237];

has the length:

L = size(A,1);

First you need to replicate it:

B = repmat(A,L,1);

and then sort the last row (z):

B(:,3) = sort(B(:,3))

which results in:

   17.4285    7.3704   -0.8979
   17.3368    7.3096   -0.8979
   17.1731    7.2011   -0.8979
   17.2693    7.2700   -0.8979
   17.0983    7.1537   -0.8979
   17.5938    7.4765   -0.8979
   ...
   17.4285    7.3704   -0.3069
   17.3368    7.3096   -0.3069
   17.1731    7.2011   -0.3069
   17.2693    7.2700   -0.3069
   17.0983    7.1537   -0.3069
   17.5938    7.4765   -0.3069

which you then could plot with 

scatter3(B(:,1),B(:,2),B(:,3));

leading to: scatter plot

Upvotes: 2

geek_girl
geek_girl

Reputation: 270

If I've understood correctly, you want to plot each plane. 

scatter(x,y,2,z)

will plot a 2D plot of x and y coordinates with points of size 2. The colours of the plot will be the linear mapping of the z coordinates.

You can proceed in the same fashion for the other planes...

scatter(x,z,2,y)

will plot the xz plane

Alternatively you could just plot the 3D pointcloud using 

scatter3(x,y,z)

then click on the rotate button in the MATLAB figure and right click on the figure to change the view (to xy, xz,yz plane)

Upvotes: 0

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