How to plot isosurfaces using 3 vector columns of data?

7 次查看（过去 30 天）

Bacha Munir 2024-6-3

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2124851-how-to-plot-isosurfaces-using-3-vector-columns-of-data

评论： Bacha Munir 2024-6-25

isosurface plot.txt

I have 4 columns. The first three are the x,y, and z coordinates while the last one is the iso level. How can I plot them in Matlab?. thanks

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Mathieu NOE 2024-6-3

在 MATLAB Online 中打开

isosurface plot.txt

what are we supposed to do with the iso level - to do a countour plot ?

you can first plot your x,y,z data as a scatter plot

data = readmatrix('isosurface plot.txt',"NumHeaderLines",8);

figure

scatter3(data(:,1), data(:,2), data(:,3))

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Mathieu NOE 2024-6-3

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2124851-how-to-plot-isosurfaces-using-3-vector-columns-of-data#answer_1466706

编辑：Mathieu NOE 2024-6-3

在 MATLAB Online 中打开

maybe this ?

pretty much what you could obtain with contour (in principe ,but I am not sure how to make contour work on your data)

NB that I extracted the "level" Z data using a certain tolerance (tolZ), then from the raw coordinates I made a closed smoothed curve using smoothn available from the Fex : smoothn - File Exchange - MATLAB Central (mathworks.com)

hope it helps !

data = readmatrix('isosurface plot.txt',"NumHeaderLines",8);
x = data(:,1);
y = data(:,2);
z = data(:,3);
% 
figure
scatter3(x, y, z)
hold on
% get level data (here we are dealing with one value only)
level = unique(data(:,4));
level(isnan(level)) = [];
% set a tolerance on the z coordinates 
tolZ = level/30;
ind = abs(data(:,3) - level)<tolZ;
xa = data(ind,1);
ya = data(ind,2);
za = data(ind,3);
% select points and re order with theta in ascending order
centroid_x = mean(xa);
centroid_y = mean(ya);
[th,r] = cart2pol(xa-centroid_x,ya-centroid_y);
[th,ia,ic] = unique(th);
r = r(ia);
za = za(ia);
% closing the curve
r(end+1) = r(1);
th(end+1) = th(1)+2*pi;
za(end+1) = za(1);
[xa,ya] = pol2cart(th,r);
xa = xa + centroid_x;
ya = ya + centroid_y;
plot3(xa, ya, za,'*g')
% create smoothed closed curve
A = smoothn({xa, ya, za},10);
xs = A{1};
ys = A{2};
zs = A{3};
% force the smoothed curve to be closed
xs(end+1) = xs(1);
ys(end+1) = ys(1);
zs(end+1) = zs(1);
plot3(xs,ys,zs,'r','linewidth',3)
  

26 个评论
显示 24更早的评论隐藏 24更早的评论

Mathieu NOE 2024-6-7

在 MATLAB Online 中打开

to your question about the magenta color , you just need

this line : p.FaceColor = grayColor

must be changed into : p.FaceColor = 'm';

then you should get , like me :

now , if you had this line at the end of the code :

shading interp

then you would get this (this is the color scheme of the color map by default ("parula" colormap)

the color is linked to the z value of your data , in relationship to the colormap you have choosen

full code for uniform magenta rendering :

%% Load the data
fid=fopen('isosurface plot.txt');
ZZ=textscan(fid,'%f %f %f %f','headerlines',8);
data = [ZZ{1} ZZ{2} ZZ{3}];
fclose(fid);
% Remove rows containing NaN values
data = data(all(~isnan(data), 2), :);
%% Run  program
[t,tnorm]=MyRobustCrust(data(:,1:3));
%% plot of the output triangulation
figure(1)
grayColor = [.7 .7 .7];
title('Output Triangulation','fontsize',14)
p = trisurf(t,data(:,1),data(:,2),data(:,3));
p.EdgeColor = 'none';
% p.FaceColor = grayColor;
p.FaceColor = 'm';
view(-40,24)
box on
camlight(40,40)                                
camlight(-20,-10)

Mathieu NOE 2024-6-7

在 MATLAB Online 中打开

for your geometry file , the logic is quite similar

so once we have plotted the surface , we add the geometry dots with scatter3 function (you can tweak the color , dot size , etc with the function arguments)

result :

code :

clc
clearvars
%% Load the surface data
fid=fopen('surface plot 1.txt');
Z=textscan(fid,'%f %f %f %f','headerlines',8);
data = [Z{1} Z{2} Z{3}];
fclose(fid);
% Remove rows containing NaN values
data = data(all(~isnan(data), 2), :);
%% Load the geometry  data
fid=fopen('geometry.txt');
Z=textscan(fid,'%f %f %f','headerlines',9);
geo = [Z{1} Z{2} Z{3}];
fclose(fid);
% Remove rows containing NaN values
geo = geo(all(~isnan(geo), 2), :);
%% Run  program
[t,tnorm]=MyRobustCrust(data(:,1:3));
%% plot of the output triangulation
figure(1)
grayColor = [.7 .7 .7];
title('Output Triangulation','fontsize',14)
p = trisurf(t,data(:,1),data(:,2),data(:,3));
p.EdgeColor = 'none';
p.FaceColor = 'm';
view(-40,24)
box on
camlight(40,40)                                
camlight(-20,-10)
% now add the geometry dots
hold on 
scatter3(geo(:,1),geo(:,2),geo(:,3),5,'filled');
hold off

Bacha Munir 2024-6-21

Hello. I have downloaded the smoothn file which works fine for other codes. I have then modified this code but it cannot work. Could you please check and correct it?. Thanks.

clc

clearvars

% Load the surface data

fid=fopen('surface plot 1.txt');

Z=textscan(fid,'%f %f %f %f','headerlines',8);

xx=Z{1};yy=Z{2};zz=Z{3};

Zr=smoothn({xx,yy,zz});

data = [Z{1} Z{2} Z{3}];

fclose(fid);

% Remove rows containing NaN values

data = data(all(~isnan(data), 2), :);

% Load the geometry data

fid=fopen('geometry.txt');

Z=textscan(fid,'%f %f %f','headerlines',9);

geo = [Z{1} Z{2} Z{3}];

fclose(fid);

% Remove rows containing NaN values

geo = geo(all(~isnan(geo), 2), :);

% Run program

[t,tnorm]=MyRobustCrust(data(:,1:3));

% plot of the output triangulation

figure(1)

grayColor = [.7 .7 .7];

title('Output Triangulation','fontsize',14)

p = trisurf(t,data(:,1),data(:,2),data(:,3),Zr{1},Zr{2},Zr{3});

p.EdgeColor = 'none';

p.FaceColor = 'b';

view(-40,24)

box on

camlight(40,40)

camlight(-20,-10)

hold on

% now add the geometry dots

scatter3(geo(:,1),geo(:,2),geo(:,3),5,'filled');

hold on

Mathieu NOE 2024-6-24

在 MATLAB Online 中打开

hello

I don't thinl smoothn is appropriate here for scattered data representing a closed surface - I got a bad result here - this is how I changed a bit your code :

clc
clearvars
%% Load the surface data
fid=fopen('surface plot 1.txt');
Z=textscan(fid,'%f %f %f %f','headerlines',8);
data = [Z{1} Z{2} Z{3}];
fclose(fid);
% Remove rows containing NaN values
data = data(all(~isnan(data), 2), :);
% try do some smoothing 
xx=data(:,1);yy=data(:,2);zz=data(:,3);
Zr=smoothn({xx,yy,zz});
data = [Zr{1} Zr{2} Zr{3}];
%% Load the geometry  data
fid=fopen('geometry.txt');
Z=textscan(fid,'%f %f %f','headerlines',9);
geo = [Z{1} Z{2} Z{3}];
fclose(fid);
% Remove rows containing NaN values
geo = geo(all(~isnan(geo), 2), :);
%% Run  program
[t,tnorm]=MyRobustCrust(data(:,1:3));
%% plot of the output triangulation
figure(1)
grayColor = [.7 .7 .7];
title('Output Triangulation','fontsize',14)
p = trisurf(t,data(:,1),data(:,2),data(:,3));
p.EdgeColor = 'none';
p.FaceColor = 'm';
view(-40,24)
box on
camlight(40,40)                                
camlight(-20,-10)
% now add the geometry dots
% 
hold on 
scatter3(geo(:,1),geo(:,2),geo(:,3),5,'filled');
hold off