surf colors with cylinder output

Hi, I have radius data for given depths. I'd like to plot it in 3D with colors matching the radius range. I'm not sure how to construct color palette correctly. r = 3.6247 3.6329 3.6412 3.6494; (r has over 8000 points) [x,y,z]=cylinder(r,10); surf(x,y,z). I can assign color with z surf(x,y,z,z) but I'm really after the visual change in radius. e.g red for radius lower than 3.63, yellow for 3.64 green for 3.65. (5 color ranges in total, or a color palette would be even better).

Below is 8000 radii used with z as color. I need to get the colors right, red where the radius is lowest of pipe's nominal ID.

Thank you!

Answer 1

[Mike Garrity]

You're creating a lot of cylinders which each have a constant radius? If so, then something like this should work:

cla
hold on
for i=1:100
  r = 1+rand(1);
  [x,y,z] = cylinder(r,10);
  surf(x,y,z+i,r*ones(size(z)),'EdgeColor','none');
end
view(3)
colorbar

What's going on there is that the 4th argument to surf is a CData array which is used for the face colors.

Of course, you could also combine them into a single surf, like this:

cla
hold off
x = [];
y = [];
z = [];
c = [];
for i=1:100
  r = 1+rand(1);    
  [xt,yt,zt] = cylinder(r,10);
  x(end+1,:) = xt(1,:);
  y(end+1,:) = yt(1,:);
  z(end+1,:) = i*ones(size(zt(1,:)));
  c(end+1,:) = r*ones(size(zt(1,:)));
end
surf(x,y,z,c,'EdgeColor','none');

[Mike]

works great!

Thank you.