how to plot by scatter3 a 3D matrix with its elements being logic variables?

I made a 3D matrix representing a ellipsoid. The elements are logic variables, 1 or NaN. I thought this 3D matrix as Cartesian coordinate and the points on it. I want to plot this by using scatter3. But scatter3 accepts 1D vectors as inputs for position. (Before, I made a 2D matrix representing a ellipsoid and plotted this by using imagesc. This function accepts 2D matrix and don't require position vectors.)

Here is the code.

%making a coordinate
Sx=1; Sy=1; Sz=1; Nx=50; Ny=50; Nz=50; dx= Sx/Nx; dy=Sy/Ny; dz=Sz/Nz;

xa=[0:Nx-1]*dx;
ya=[0:Ny-1]*dy;
za=[0:Nz-1]*dz;
xa=xa-mean(xa);
ya=ya-mean(ya);
za=za-mean(za);
[X,Y,Z]=meshgrid(xa,ya,za);

%ellipsoid
rx=0.5;
ry=0.35;
rz=0.2;
A=zeros(length(xa),length(ya),length(za));
A(((X/rx).^2+(Y/ry).^2+(Z/rz).^2)<=1)=1; 
A(((X/rx).^2+(Y/ry).^2+(Z/rz).^2)>1)=NaN;

Now I don't know how to transform the matrix for scatter3

Answer 1

[jonas]

You can use your logic data in A to set the color and your X, Y and Z data for coordinates.

scatter3(X(:),Y(:),Z(:),[],A(:))

[Woo-Seok Lee]

Thank you so much!!!

[Woo-Seok Lee]

I want to plot another ellipsoid with half radius of the first one.

rx=0.5;
ry=0.35;
rz=0.2;
A=zeros(length(xa),length(ya),length(za));
A(((X/rx).^2+(Y/ry).^2+(Z/rz).^2)<=1)=1;
A(((X/rx).^2+(Y/ry).^2+(Z/rz).^2)>1)=NaN;
figure, scatter3(X(:),Y(:),Z(:),[],A(:)), colormap cool, axis equal, axis tight, grid on;
hold on;
rx=rx/2;
ry=ry/2;
rz=rz/2;
A2=zeros(length(xa),length(ya),length(za));
A2(((X/rx).^2+(Y/ry).^2+(Z/rz).^2)<=1)=0;
A2(((X/rx).^2+(Y/ry).^2+(Z/rz).^2)>1)=NaN;
scatter3(X(:),Y(:),Z(:),[],A2(:));
hold off;

But the the latter scatter3 function doesn't make any change. When I only run the code:

scatter3(X(:),Y(:),Z(:),[],A2(:));

then smaller ellipsoid is shown. When the whole code run, only the bigger one is shown. What's the problem?

[jonas]

That's because the smaller ellipsiod is hidden by the larger one. You can increase transparency of the larger one to see the smaller.

save handles when you plot, i.e.

h1=scatter3(X(:),Y(:),Z(:),[],A(:))
h2=scatter3(X(:),Y(:),Z(:),[],A2(:));

then increase transparency of the larger one

set(h1,'markeredgealpha',0.05)

[Woo-Seok Lee]

Thank you soooo much!!!

[jonas]

Happy to help!

[Valeriy]

I try tor reproduce command set(h1,'markeredgealpha',0.05),

but I have obtained message:

Error using specgraph.scattergroup/set
The name 'markeredgealpha' is not an accessible property for an instance
of class 'scattergroup'.

Help for scattergroup properties don't show presence of "markeredgealpha". How it works?

[jonas]

You probably have to specify that already when plotting, i.e.:

scatter(..., 'markeredgealpha',0.05)