Plotting thickness data to a cylinder.

First off, I am completely new to MATLAB and not really sure where to start.

I have large datasets (approximately 170,000 points) that I am trying to plot to a cylinder surface. It is Ultrasonic thickness readings taken about the circumference of a pipe.

I have X, Y, Z coordinates for every point and would like to display the thickness reading value as a colormap, any recommendations would be greatly appreciated.

*Edit..... I've attached a photo of the original excel data, rows represent circumferential position, columns length about the pipe axis and the color pallet represents remaining wall thickness (in this instance between 12mm-20mm)

Ideally I would like to be able to plot to be a representative image of the pipe itself as pictured (that was just cheated by applying an image of the excel data to a pipe section as a material in AutoCAD)

[darova]

Do you have any picture? What result you are expecting?

[Andy M]

I was able to find some guidance in answers to be able to plot the cylinder to the correct size, with the correct amount of divisions in circumferential and Z axis, but am having trouble linking the data to generate the colormap.

[Andy M]

For the example I am using data a 600 x 35 test sample (600 points about circumference, 35 long) just not sure how to add it in. The following was provided by another user which gets the cylinder size right but I dont know how to input my data for the colormap to represent remaining wall thickness

Radius = 300. ;           % Radius of the cylindrical shell
theta = 360. ;           % Angle of the Cylinder
Height = 35. ;           % Height of the Cylinder
%
NH = 35 ;                % Number of Elements on the Height
NT = 600 ;               % Number of Angular Dicretisation 

% Discretizing the Height and Angle of the cylinder
nH = linspace(0,Height,NH) ;
nT = linspace(0,theta,NT)*pi/180 ;
[H, T] = meshgrid(nH,nT) ;
% Convert grid to cylindrical coordintes
X = Radius*cos(T); 
Y = Radius*sin(T);
Z = H ;

th = linspace(0,2*pi) ;
R = @(th) [1 0 0 ;0 cos(th) -sin(th) ; 0 sin(th) cos(th)] ; % rotation matrix alon x-axes
h = surf(X,Y,Z) ;
axis([-2 2 -2 2 -2 2])
coor = [X(:) Y(:) Z(:)] ;
for i = 1:length(th)
    
    coor1 = coor*R(th(i)) ;
    X1 = reshape(coor1(:,1),NT,NH) ; 
    Y1 = reshape(coor1(:,2),NT,NH) ; 
    Z1 = reshape(coor1(:,3),NT,NH) ; 
    set(h,'XData',X1,'YData',Y1,'ZData',Z1) ;
    drawnow    
    pause(0.1)
end

[darova]

Can you attach the data? For my expertiments

[Andy M]

I have atached the data sample I've been playing with.

Answer 1

[darova]

Use this

A = xlsread('test matlab.xlsx');
%%
x = A(:,2);
y = A(:,3);
T = A(:,5:end);
z = 1:size(t,2);            % 1 2 3 ... number of columns

[X,Z] = ndgrid(x,z);        % 2d matrix
[Y,~] = ndgrid(y,z);        % 2d matrix

surf(X,Y,Z,T,'edgecolor','none')

axis vis3d 
view(3)
opengl software 
caxis([15 23])
colorbar

[Andy M]

Thank you so much, that worked perfectly!

[SHIVA LADI]

Can you please attach the test matlab.xlsx fie.

[M J]

I never saw the .xlsx file for this solution, it looks like it was attached but it doesn't show?

[Simson Hutagalung]

Can you show the excel file? Thank you

Answer 2

[Ameer Hamza]

I don't understand what you are trying to do inside the for-loop, but the following code shows how to map a texture on a cylinder surface. I used an image as a texture map. You can adapt it according to your need.

im = imread('peacock.jpg');

r = 5;
[X,Y,Z] = cylinder(r, 100);
h = 20;
Z = Z*h;
surf(X, Y, Z, flip(im), 'FaceColor', 'texturemap', 'EdgeColor', 'none');
daspect([1 1 1])