colorbar scale is not correct when using isosurface and patch plots

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Why is the color bar here giving me the values of the transparency "alpha" and not my data values that I am plotting?
Code:
Nx = 128;
Ny = 128;
Nz = 128;
Lx =128;
Ly = 128;
Lz = 128;
xi = (0:Nx-1)/Nx*2*pi;
xi_x = 2*pi/Lx;
x = xi/xi_x;
yi = (0:Ny-1)/Ny*2*pi;
yi_y = 2*pi/Ly;
y = yi/yi_y;
zi = (0:Nz-1)/Nz*2*pi;
zi_z = 2*pi/Lz;
z = zi/zi_z;
dx = Lx/Nx;
dy = Ly/Ny;
dz = Lz/Nz;
[X,Y,Z] = meshgrid(x,y,z);
%Sizing
fontSize = 16;
frames2Plot = [1 2 3 4 5 6];
numF = length(frames2Plot);
mB = 0.12;
mT = 0.05;
mL = 0.9;
sV = 0.005;
wC = 0.02;
sC = 0.02;
mC = 0.03;
mR = wC + sC + mC;
sH = 0.01;
sV = 0.01;
W = (1 - mL - mR - (numF/2-1)*sH) / (numF/2);
H = (1 - mT - mB - sV) / 2;
filelocation1 = 'C:\Users\Data\';
n = reshape(readmatrix([filelocation1,'Data',num2str(100),'.txt']),128,128,128);
Error using readmatrix
Unable to find or open 'C:\Users\Data\Data100.txt'. Check the path and filename or file permissions.
f = figure('Position',[14 63 851 600],'Renderer','Painters');
i = 1.5e11;
surf1 = isosurface(X,Y,Z,n,i);
p1 = patch(surf1);
isonormals(X,Y,Z,n,p1);
set(p1,'FaceColor','black','EdgeColor','none','FaceAlpha',0.1);
daspect([1,1,1])
view(3);
camlight; lighting gouraud
i = 2.5e11;
surf2 = isosurface(X,Y,Z,n,i);
p2 = patch(surf2);
isonormals(X,Y,Z,n,p2);
set(p2,'FaceColor','#7E2F8E','EdgeColor','none','FaceAlpha',0.2);
i = 3.5e11;
surf3 = isosurface(X,Y,Z,n,i);
p3 = patch(surf3);
isonormals(X,Y,Z,n,p3);
set(p3,'FaceColor','red','EdgeColor','none','FaceAlpha',0.3);
i = 4.5e11;
surf4 = isosurface(X,Y,Z,n,i);
p4 = patch(surf4);
isonormals(X,Y,Z,n,p4);
set(p4,'FaceColor','yellow','EdgeColor','none','FaceAlpha',1);
grid on;
xlabel('x(m)'); ylabel('y(m)'); zlabel('z(m)');
c = colorbar;
for i = 1:numF
hAxis(i).Position = [mL, (numF - i) * (sV + H) + mB , W, H];
end
c.Position = [mL + W + sC, mB, wC, 1 - mB - mT];
c.Label.String = 'values';
The color bar should be showing the value i and not "alpha", is there a way to fix this?? Thanks
  3 Comments
Jamie Al
Jamie Al on 7 Dec 2022
I attached a zip file with one text file data. Now, if I don't use patch, just isosurface then my colorbar values are correct. Why is that?
figure;
i = 2.5e11;
isosurface(X,Y,Z,n,i);
alpha(0.0008)
hold on;
i = 3.5e11;
isosurface(X,Y,Z,n,i);
alpha(0.2)
hold on;
i = 4.5e11;
isosurface(X,Y,Z,n,i);
view(3)
colorbar;
Voss
Voss on 8 Dec 2022
unzip('ne231.zip')
Nx = 128;
Ny = 128;
Nz = 128;
Lx =128;
Ly = 128;
Lz = 128;
xi = (0:Nx-1)/Nx*2*pi;
xi_x = 2*pi/Lx;
x = xi/xi_x;
yi = (0:Ny-1)/Ny*2*pi;
yi_y = 2*pi/Ly;
y = yi/yi_y;
zi = (0:Nz-1)/Nz*2*pi;
zi_z = 2*pi/Lz;
z = zi/zi_z;
dx = Lx/Nx;
dy = Ly/Ny;
dz = Lz/Nz;
[X,Y,Z] = meshgrid(x,y,z);
%Sizing
fontSize = 16;
frames2Plot = [1 2 3 4 5 6];
numF = length(frames2Plot);
mB = 0.12;
mT = 0.05;
mL = 0.9;
sV = 0.005;
wC = 0.02;
sC = 0.02;
mC = 0.03;
mR = wC + sC + mC;
sH = 0.01;
sV = 0.01;
W = (1 - mL - mR - (numF/2-1)*sH) / (numF/2);
H = (1 - mT - mB - sV) / 2;
n = reshape(readmatrix('ne231.txt'),128,128,128);
f = figure('Position',[14 63 851 600],'Renderer','Painters');
i = 2.5e11;
isosurface(X,Y,Z,n,i);
alpha(0.0008)
hold on;
i = 3.5e11;
isosurface(X,Y,Z,n,i);
alpha(0.2)
hold on;
i = 4.5e11;
isosurface(X,Y,Z,n,i);
view(3)
colorbar;

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Answers (1)

Voss
Voss on 8 Dec 2022
Is this how it should be?
unzip('ne231.zip')
Nx = 128;
Ny = 128;
Nz = 128;
Lx =128;
Ly = 128;
Lz = 128;
xi = (0:Nx-1)/Nx*2*pi;
xi_x = 2*pi/Lx;
x = xi/xi_x;
yi = (0:Ny-1)/Ny*2*pi;
yi_y = 2*pi/Ly;
y = yi/yi_y;
zi = (0:Nz-1)/Nz*2*pi;
zi_z = 2*pi/Lz;
z = zi/zi_z;
dx = Lx/Nx;
dy = Ly/Ny;
dz = Lz/Nz;
[X,Y,Z] = meshgrid(x,y,z);
%Sizing
fontSize = 16;
frames2Plot = [1 2 3 4 5 6];
numF = length(frames2Plot);
mB = 0.12;
mT = 0.05;
mL = 0.9;
sV = 0.005;
wC = 0.02;
sC = 0.02;
mC = 0.03;
mR = wC + sC + mC;
sH = 0.01;
sV = 0.01;
W = (1 - mL - mR - (numF/2-1)*sH) / (numF/2);
H = (1 - mT - mB - sV) / 2;
cmap = [ ...
0 0 0; ... 'black'
126 47 142; ... '#7E2F8E'
255 0 0; ... 'red'
255 255 0; ... 'yellow'
]/255;
% filelocation1 = 'C:\Users\Data\';
n = reshape(readmatrix('ne231.txt'),128,128,128);
f = figure('Position',[14 63 851 600],'Renderer','Painters');
i = 1.5e11;
surf1 = isosurface(X,Y,Z,n,i);
p1 = patch(surf1);
isonormals(X,Y,Z,n,p1);
set(p1,'FaceColor',cmap(1,:),'EdgeColor','none','FaceAlpha',0.1);
daspect([1,1,1])
view(3);
camlight; lighting gouraud
i = 2.5e11;
surf2 = isosurface(X,Y,Z,n,i);
p2 = patch(surf2);
isonormals(X,Y,Z,n,p2);
set(p2,'FaceColor',cmap(2,:),'EdgeColor','none','FaceAlpha',0.2);
i = 3.5e11;
surf3 = isosurface(X,Y,Z,n,i);
p3 = patch(surf3);
isonormals(X,Y,Z,n,p3);
set(p3,'FaceColor',cmap(3,:),'EdgeColor','none','FaceAlpha',0.3);
i = 4.5e11;
surf4 = isosurface(X,Y,Z,n,i);
p4 = patch(surf4);
isonormals(X,Y,Z,n,p4);
set(p4,'FaceColor',cmap(4,:),'EdgeColor','none','FaceAlpha',1);
grid on;
xlabel('x(m)'); ylabel('y(m)'); zlabel('z(m)');
c = colorbar;
colormap(cmap)
n_colors = size(cmap,1);
caxis([1 n_colors+1]*1e11);
c.YTick = ((1:n_colors)+0.5)*1e11;
for i = 1:numF
hAxis(i).Position = [mL, (numF - i) * (sV + H) + mB , W, H];
end
c.Position = [mL + W + sC, mB, wC, 1 - mB - mT];
c.Label.String = 'values';

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