How to make color plots in 3D?

Question

Jamie Al 2022-10-12

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1824063-how-to-make-color-plots-in-3d

评论： Walter Roberson 2022-10-15

inferno.m

I am using isosurface to create 3D plots, but the colors aren't what I want. I have two examples with 2D plots with nice colormap and 3D plots using isosurface. I would like to reprduce the colors from 2D plot to my 3D plot if that's possible:

2D plot:

Nx = 256;

Ny = 256;

Lx = 128;

Ly = 128;

%coord mapping

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;

A = 2*pi / Lx;

B = 2*pi / Ly;

x0 = 64;

y0 = 64;

rx0 = 20;

ry0 = 20;

p = 3;

b = 0.015;

c = 12;

d = 1;

a = 4;

[X2,Y2] = meshgrid(x,y);

theta2 = atan2(Y2 -y0, X2-x0) - (pi/c);

p02 = ((X2-x0) .* (X2-x0)) /(rx0 * rx0) + ((Y2-y0) .* (Y2-y0))/(ry0 * ry0);

n2 =d + a * exp((-1. * p02 .* (1 - b * cos(c * theta2))).^p) ;

%plot

figure

pcolor(X2,Y2,n2); colorbar; colormap('inferno'); shading flat; axis tight;

grid on;

The same example for 3D:

Nx = 256;

Ny = 256;

Nz = 256;

Lx = 128;

Ly = 128;

Lz = 128;

%coord mapping

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;

A = 2*pi / Lx;

B = 2*pi / Ly;

x0 = 64;

y0 = 64;

z0 = 64;

rx0 = 20;

ry0 = 20;

rz0 = 20;

p = 3;

b = 0.015;

c = 12;

d = 1;

a = 4;

[X,Y,Z] = meshgrid(x,y,z);

theta = atan2(Y -y0, X-x0) - (pi/c);

p0 = ((X-x0) .* (X-x0)) /(rx0 * rx0) + ((Y-y0) .* (Y-y0))/(ry0 * ry0) + ((Z-z0) .* (Z-z0))/(rz0 * rz0);

n =d + a * exp((-1. * p0 .* (1 - b * cos(c * theta))).^p) ;

%plotting

figure

isosurface(X,Y,Z,n);

colorbar;

shading flat;

grid on;

xlabel('x'); ylabel('y'); zlabel('z');

3 个评论
显示 1更早的评论隐藏 1更早的评论

Adam Danz 2022-10-12

For starters, you'll need to set the same custom colormap - colormap('inferno') (pretty neat, by the way).
See this example in the isosurface documentation that shows how to control surface color by using patch along with the isosurface outputs. https://www.mathworks.com/help/matlab/ref/isosurface.html#mw_0340c7e3-87a1-489e-99ec-454313c25169
Investigate the n variable to make sure it's doing what you want it to do.

See also the clim function which may be helpful to scale the colors.

Jamie Al 2022-10-15

Thanks! This colormap 'inferno' is from someone else who converted from Python and it's very useful. I can make 2D slices and use this colormap, but I was thinking maybe 3D countor plots are better here.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2022-10-12

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1824063-how-to-make-color-plots-in-3d#answer_1072898

在 MATLAB Online 中打开

If you

help isosurface

then currently Example 1 shows taking the output of isosurface() and passing it to patch() and then modifying the patch properties such as setting the face color.

  Example 1:
       [x y z v] = flow;
       p = patch(isosurface(x, y, z, v, -3));
       isonormals(x,y,z,v, p)
       p.FaceColor = 'red';
       p.EdgeColor = 'none';
       daspect([1 1 1])
       view(3)
       camlight; lighting phong
 

2 个评论
显示无隐藏无

Jamie Al 2022-10-15

在 MATLAB Online 中打开

Thanks, but I was wondering if I can do something like 3D contour plots using MATLAB. I can take 2D slices and use the MATLAB contoru function like:

for i = 140
figure(22)
contour3(X(:,:,i), Y(:,:,i), n(:,:,i));
end

But is there a way to make 3D contour plots in MATLAB similar to these?

Walter Roberson 2022-10-15

在 MATLAB Online 中打开

Loop isosurface() calls, each with a different iso level. For example,

N = 10;  %number of surfaces
cmap = parula(N);
[minn, maxn] = bounds(n, 'all');
L = linspace(minn, maxn, N);
for K = 1 : N
   p = patch(isosurface(X, Y, n, L(K)));
   p.FaceColor = cmap(K,:);
   p.EdgeColor = 'none';
   p.FaceAlpha = 0.6;
end
view(3)