MATLAB: Contour plot control in Surfc function

3d plotscontourfigureMATLAB

I have some questions in handling surfc functions

In, surfc functions

[rr,thth]=meshgrid(0:0.005:0.7,0:1:360);
xx=rr.*cosd(thth);
yy=rr.*sind(thth);
rrr=1/4.5*(sqrt(xx.^2+yy.^2)).^3-1/8*(sqrt(xx.^2+yy.^2)).^2+0.25;%rrr=1/4*(sqrt(xx.^2+yy.^2)).^4-1/2*(sqrt(xx.^2+yy.^2)).^2-cosd(8*thth)
rrr(:)=(rrr(:)-min(min(rrr)))/(max(max(rrr))-min((min(rrr))));
zzz=sin(rrr)./rrr;
surfc(xx,yy,rrr); shading flat; caxis([0 1.0]);
 ylim([-2 2]);xlim([-2 2])
zlim([-1 1]);
view(45,70);

In the above codes, I want to change the contour level step to 0.05 and contour position at z=-0.8, not z=0 (in default)

How can I change it ?

If I type contour('LevelStep',0.05) as contour examples, blank figures are pop up.

Also I cannot find the reference to control contour plot positions.

Can anyone help me ? Thanks.

Best Answer

I did not see this before.

For the second, see: Customizing contour plots part 2 I asked about this a while ago, and MathWorks provided the solution that I then brought to Yair Altman’s attention. He posted it on his Undocumented MATLAB site.

Related Solutions

MATLAB: Plot quiver onto the base of a 3D plot

This seems to approximate what I believe you want:

[x,y] = meshgrid(-80:80, -80:80);
z = -(cosd(x).^2 + cosd(y).^2).^2;
mesh(x,y,z)
grid
[xx,yy] = meshgrid(-80:10:80, -80:10:80);
zz = -(cosd(xx).^2 + cosd(yy).^2).^2;
[U,V] = gradient(zz);
hold on
h = quiver3(xx,yy,ones(size(zz))*min(zlim),U,V,zeros(size(zz)));
hold off
grid on
view(-30,30)

producing:

plot quiver onto the base of a 3D plot - 2019 06 21.png

To plot it along the surface itself:

[x,y] = meshgrid(-80:80, -80:80);
z = -(cosd(x).^2 + cosd(y).^2).^2;
mesh(x,y,z)
grid
[xx,yy] = meshgrid(-80:10:80, -80:10:80);
zz = -(cosd(xx).^2 + cosd(yy).^2).^2;
[U,V,W] = surfnorm(xx,yy,zz);                           % Calculate Surface Normals
dW = gradient(W);                                       % Gradient Of ‘W’
hold on
h = quiver3(xx,yy,zz,U,V,dW);
hold off
grid on
view(-30,60)

(There may be better mathematical expressions for the same idea.)

producing:

plot quiver onto the base of a 3D plot (2) - 2019 06 21.png

MATLAB: How to plot feasible space in 3d, after subtracting multiple inequalities

Creating a binary 3d matrix does the job indeed. A 3d viewer code is not even necessary then... isosurface does the job:

clear all;clc;close all;
% density
n=.3;
% create coordinates
[xx,yy,zz] = meshgrid(-15:n:15,-15:n:15,-15:n:15);
% boundary condition 1
rr = sqrt(xx.^2 + yy.^2 + zz.^2);
% boundary condition 2 
rr2 = xx.^2+yy.^2-zz;
% boundary condition 3
rr3 = xx;
% region
region3= rr<10 & rr2<10 & rr3<2.5;
p=patch(isosurface(region3,0.5))
set(p,'FaceColor','red','EdgeColor','none');
daspect([1,1,1])
view(3); axis equal
camlight 
lighting gouraud
grid on

Thanks for your help!

Best Answer

Related Solutions

MATLAB: Plot quiver onto the base of a 3D plot

MATLAB: How to plot feasible space in 3d, after subtracting multiple inequalities

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