I would like to plot an interpolated 3d Surface between two faces, i.e. the third face of a truncated cone. my plot isn't working but I'm not sure what is wrong

r1=0.5;

% t1=[(0:0.1:2*pi),0];

t1=0:0.1:2*pi;

X1=r1*cos(t1);

Y1=r1*sin(t1);

n1=numel(X1);

Z1=zeros(1,n1);

DT=delaunay(X1,Y1);

trisurf(DT,X1,Y1,Z1);

hold;

r2=0.25;

% t2=[(0:0.1:2*pi),0];

t2=0:0.1:2*pi;

X2=r2*cos(t2);

Y2=r2*sin(t2);

n2=numel(X2);

Z2=200*ones(1,n2);

DT2=delaunay(X2,Y2);

trisurf(DT2,X2,Y2,Z2);

X= [X1,X2];

Y=[Y1,Y2];

Z=[Z1,Z2];

[xq,yq]=meshgrid(X,Y);

zq=ones(126).*Z;

surf(xq,yq,zq);

Answer 1

[Star Strider]

TThis does not look like a cone to me at all.

What do you want to do?

r1=0.5;
% t1=[(0:0.1:2*pi),0];
t1=0:0.1:2*pi;
X1=r1*cos(t1);
Y1=r1*sin(t1);
n1=numel(X1);
Z1=zeros(1,n1);

DT=delaunay(X1,Y1);
trisurf(DT,X1,Y1,Z1);
hold;

Current plot held

r2=0.25;
% t2=[(0:0.1:2*pi),0];
t2=0:0.1:2*pi;
X2=r2*cos(t2);
Y2=r2*sin(t2);
n2=numel(X2);
Z2=200*ones(1,n2);

DT2=delaunay(X2,Y2);
trisurf(DT2,X2,Y2,Z2);

X= [X1,X2];
Y=[Y1,Y2];
Z=[Z1,Z2];

[xq,yq]=meshgrid(X,Y);
zq=ones(126).*Z;
surf(xq,yq,zq);
view(-27,30)

My approach to a truncated cone (assuming my interpretation matches yours), woudl be something like this —

r = [1; 2];                                                                                         % Radius Multipliers
h = [0; 3];                                                                                         % Height Multipliers
a = linspace(0, 2*pi);                                                                              % Angle Vector
cyl = [cos(a); sin(a)]                                                                              % Circles

cyl = 2x100

1.0000 0.9980 0.9920 0.9819 0.9679 0.9501 0.9284 0.9029 0.8738 0.8413 0.8053 0.7660 0.7237 0.6785 0.6306 0.5801 0.5272 0.4723 0.4154 0.3569 0.2969 0.2358 0.1736 0.1108 0.0476 -0.0159 -0.0792 -0.1423 -0.2048 -0.2665 0 0.0634 0.1266 0.1893 0.2511 0.3120 0.3717 0.4298 0.4862 0.5406 0.5929 0.6428 0.6901 0.7346 0.7761 0.8146 0.8497 0.8815 0.9096 0.9341 0.9549 0.9718 0.9848 0.9938 0.9989 0.9999 0.9969 0.9898 0.9788 0.9638

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figure
surf(r*cyl(1,:), r*cyl(2,:), h.*[ones(size(a)); ones(size(a))], 'FaceColor','b', 'FaceAlpha',0.5)   % Plot Cone
hold on
patch((r(1)*cyl(1,:)), (r(1)*cyl(2,:)), ones(size(a))*h(1), 'r')                                    % Plot Lower Cap
patch(r(2)*cyl(1,:), r(2)*cyl(2,:), ones(size(a))*h(2), 'g')                                        % Plot  Upper Cap
hold off
grid on
axis('equal')
view(-27,30)

This is my interpretation of a truncated cone with end-caps.

.

[Hayat]

thank you this looks closer to what i was trying to achieve but i was trying to create meshed surfaces that could be individually labelled/coloured and then exported with labelled faces . In more details: i was after a meshed surface of a truncated cone but with the ability to easily manipulate its height and the diamter of the two circular faces. The end goal is to also have the ability to label each face and then duplicated the cone in a group if that makes sense. like make a group of 5 for example that i could then export as a mesh with labelled faces into a FEM solver. i thought to do this creating the mesh of the two circular faces and then interpolating the third face as a meshed surface which what i was attempting to do with my code

[Hayat]

is there a better way to create the meshes off each face from the plot in the code you shared?

[Hayat]

I've tried adding this but unsure if im doing this the best way for my goals

x=r*cyl(1,:);

y=r*cyl(2,:);

z=h.*[ones(size(a)); ones(size(a))];

T = delaunay(x,y,z);

trisurf(T,x,y,z);

[Star Strider]

I do not have much experience with triangulated surfaces (or FEM simulations), however copying an example from the trisurf documentation and adaptting it to my code produces this result —

r = [1; 2];                                                                                         % Radius Multipliers
h = [0; 3];                                                                                         % Height Multipliers
a = linspace(0, 2*pi);                                                                              % Angle Vector
cyl = [cos(a); sin(a)];                                                                             % Circles

figure
surf(r*cyl(1,:), r*cyl(2,:), h.*[ones(size(a)); ones(size(a))], 'FaceColor','b', 'FaceAlpha',0.5)   % Plot Cone
hold on
patch((r(1)*cyl(1,:)), (r(1)*cyl(2,:)), ones(size(a))*h(1), 'r')                                    % Plot Lower Cap
patch(r(2)*cyl(1,:), r(2)*cyl(2,:), ones(size(a))*h(2), 'g')                                        % Plot  Upper Cap
hold off
grid on
axis('equal')
view(-27,30)
title('Original ‘surf’ Plot')

x = r*cyl(1,:);
y = r*cyl(2,:);
T = delaunay(x, y);
z = h.*[ones(size(a)); ones(size(a))];

figure
trisurf(T,x,y,z, 'FaceAlpha',0.5)
grid on
colormap(turbo)
axis('equal')
view(-27,30)
title('Original ‘trisurf’ Plot')

According to the documentation example I use as a reference, ‘z’ is not an argument to delaunay in this instance.

You would have to code the end caps separately, if you want to include them.

Experiment with this to get the result you want.

.

[Hayat]

thanks! i got the top cap with the x,y,z delaunay so looks like we are on the right track. thank you!

[Star Strider]

As always, my pleasure!