I want to fit lines to the 3D points seen in the photo and get its shape But I do not know how to do it. please guide me. The points file is available.

Answer 1

[darova]

SOmething is wrong with the data you attached

s = importdata('POINT.txt');
x = s(:,1);
y = s(:,2);
z = s(:,3);
plot3(x,y,z,'.-r')

[adel hosseini]

Thank you very much for your guidance

The points file was updated

[darova]

Help me to select all conours separately liek this

s = importdata('POINT2.txt');
x = s(:,1)-mean(s(:,1));
y = s(:,2)-mean(s(:,2));
z = s(:,3)-mean(s(:,3));
ix1 = y < -2 | 2 < y | z < -5.5 | 6 < z;    % big contour
% ix2 =                                       % contour 1
% ix3 =                                       % contour 2
% ix4 =                                       % contour 3
plot(y,z,'.r')
line(y(ix1),z(ix1),'marker','o','linestyle','none')
axis equal

[adel hosseini]

Thank you in advance for your help

Do you mean that?

clc;
clear;
close all;
S = importdata('POINT2.txt');
x = S(:,1);
y = S(:,2);
z = S(:,3);
points1 = length(S);

randLoc1=randi(points1);
randPoint1(1,:)=S(randLoc1,1:3);
xr=randPoint1(1,1);
yr=randPoint1(1,2);
zr=randPoint1(1,3);

findrand=find(S(:,1)==xr & S(:,3)==zr);
leangthafindrand = size(findrand,1);
class{1}(1:leangthafindrand,:)=S(findrand,1:3);
leangthclass=size(class{1},1);

S(S(:,1)==xr & S(:,3)==zr,:)=[];
x1 = S(:,1);
y1 = S(:,2);
z1 = S(:,3);

plot(xr,zr,'.r','marker','o')
hold on
plot(x1,z1,'.b')
points2 = length(S);
minDis=0;
m=0;
k=1;
while   points2>0
    m=m+1;
    minDis=0;
    while  minDis<0.8 && points2>0
        for i=1:1:points2(1,1);
            dis{k}(i)=abs(sqrt((x1(i)-xr)^2 + (z1(i)-zr)^2));
        end
        minDis=min(dis{k});
        aa=find(dis{k}(:)==minDis);
        hold on
        plot(x1(aa),z1(aa),'.y','marker','o')
        leangtha = size(aa,1);
        p=leangthclass+leangtha;
        class{m}(leangthclass+1:p,:)=S(aa,1:3);
        leangthclass=size(class{m},1);
        
        xr=S(aa(1),1);
        yr=S(aa(1),2);
        zr=S(aa(1),3);
        plot(xr,zr,'.r','marker','o')
        axis equal
        S(S(:,1)==xr & S(:,3)==zr,:)=[];
        x1 = S(:,1);
        y1 = S(:,2);
        z1 = S(:,3);
        points2 = size(S,1);
        k=k+1;
    end
    leangthclass=1;
    endclass=class{m}(end,:);
    findend=find(class{m}(:,1)==endclass(1,1) & class{m}(:,2)==endclass(1,2) & class{m}(:,3)==endclass(1,3));
    class{m+1}(1,:)=class{m}(end,:);
    class{m}(findend(:),:)=[];
    line(class{m}(:,1),class{m}(:,3),'marker','o','linestyle','-')
   
end
class{m}(end+1,:)=class{m+1}(1,:);
class{m+1}(:,:)=[];
line(class{m}(:,1),class{m}(:,3),'marker','o','linestyle','-')

[adel hosseini]

But I want something like this: