Isosurface plots appear 2d when used with subplot

Hi all,

I'm trying to put together some isosurface plots using subplot. I want them to be 3d and rotatable. However, when I try using subplot together with isosurface, the plots appear 2d and are not rotatable. What am I missing? Consider the following, for instance:

[x,y,z] = meshgrid([-3:0.25:3]); 
V = x.*exp(-x.^2 -y.^2 -z.^2);

for i=1:4
    subplot(2,2,i);
    
    isosurface(x,y,z,V,1e-4);
end

[Saksham Gupta]

As per my understanding of your query, are unable to rotate subplots.

View function , when used with subplots ,can help in rotating each subplot individually.

Following code might be helpful to you:

[x,y,z] = meshgrid([-3:0.25:3]); 
V = x.*exp(-x.^2 -y.^2 -z.^2);
for i=1:4
    subplot(2,2,i);
    
    isosurface(x,y,z,V,1e-4);
    
    %Below line can be added 
    view(subplot(2,2,i),[10,10]);
end

Here ,[10,10] is a random elevation angle I have applied.

You may also refer to the documentation for better understanding

[Irem Altan]

Thanks! This partially solves the problem. Things are now rotatable in a 3d view but the shading is still flat compared to a single plot.

Answer 1

[Walter Roberson]

MATLAB has divides graphics calls into "high level" and "low level".

"High level" calls check whether hold is on, and if not then they erase the current axes before adding the graphics.

"low level" calls never check hold, and always go ahead and add the graphics.

There are some functions such text() that are always low level. line() is low level, but plot() is high level.

There are some graphics calls that are high level or low level depending on how you call them.

When you call isosurface() without any outputs then it calls patch() to draw the surface. It does that with a calling sequence that happens to be low level for patch. So when you call isosurface that way, the surface is just added to the current graphics, and higher level graphics functions are not invoked. In particular, view(3) is not automatically called by patch() the way it might be if a high level calling sequence had been used.

Answer 2

[William Rose]

@Irem Altan,

I find that if I click twice on the 3D rotate icon above each plot, I am able to rotate thenm. Here is a screenshot showing your four plots, with three of them rotated.

[William Rose]

@Irem Altan,

I agree with you that the 3D rotate seems to operate oddly in your example. When I first generated the figure, using your code, I moved my cursor over the plot, and the 3D rotate cursor appeared. But when I click and drag, it only pans, rather than rotating in 3D. So I clicked on the 3D rotate icon above the plot. That un-selected 3D rotate. Then I clicked it again to select 3D rotate, and then it worked.

[Irem Altan]

Thanks for that -- I hadn't realized it. However, the plots still lack the proper 3d rendering (when compared to a single plot without subplot).

[William Rose]

@Irem Altan,

I'm not sure why the rendering is not correct.

I tried using nexttile instead of subplot, to create multiple plots in one figure.

[x,y,z] = meshgrid([-3:0.25:3]); 
V = x.*exp(-x.^2 -y.^2 -z.^2);
nexttile; isosurface(x,y,z,V,1e-4);
nexttile; isosurface(x,y,z,V,1e-4);
nexttile; isosurface(x,y,z,V,1e-4);
nexttile; isosurface(x,y,z,V,1e-4);

I got the same result as with subplot: the shading was not rendered correctly.

[Irem Altan]

Thank you for trying that as well. At this point I'm not sure if this is a bug or something else. I have reached out to tech support and will see what they say.

[Yi Hui Tee]

Hi, did you get any reply on this? I am facing the same problem when trying to use subplot or nexttile.

Answer 3

[Saksham Gupta]

As per my understanding, you are telling that whole image is coming in 1 color only and not in shades as it comes for single plot.

On inputing x again as a parameter to isosurface, subplots should have the relevant shading.

For customizing colors and shading more, you should check out this documentation.

Below is the code I am using at my end :

[x,y,z] = meshgrid([-3:0.25:3]); 
V = x.*exp(-x.^2 -y.^2 -z.^2);
for i=1:4
    subplot(2,2,i);
    
    isosurface(x,y,z,V,1e-4,x);

    view(subplot(2,2,i),[10,10]);

end