Re: plotting multiple 3D spheres in the same diagram
- From: "T Neeves" <neevesjunk@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Thu, 20 Oct 2005 10:26:23 -0400
Fiona Goddard wrote:
>
>
> I am trying to create a simulation of particles moving in 3D. I've
> been using plot3 but this only draws circles, which does not really
> give an accurate 3D picture because there is no perspective (points
> "far away" are drawn the same size as "closer" ones). Ideally I'd
> like to plot each particle as a sphere at position (x,y,z) to get
> some depth perception and also so that the particles increase in
> size
> as you zoom in. I know that matlab can draw individual spheres but
> can this be extended to plot many spheres in the same diagram?
>
> Thanks
Fiona;
I was playing with code (below) to spatially visualize data in 3D
space a while back, and it sounds like something you might find
usefull. I chose cubes instead of spheres because they are much
easier to deal with, primarily because there is much less rendering
effort needed for cubes. If you are not looking for 'real-time'
rendering, spheres should work as well.
What the code does: Essentially, it puts a cube at each point in
space, then colors the cube according to the data value at that point
in space. You could play with the cube size (vs. color), I suppose.
Here's the code snippet FWIW.
- Ted
% Create some data:
tempMeas(10,10,10) = 0;
for i = 1:10
for j = 1:10
for k = 1:10
tempMeas(i,j,k) = i + j + k + 10*rand;
end
end
end
x_min = 1;
y_min = 1;
z_min = 1;
x_max = 10;
y_max = 10;
z_max = 10;
t_min = min(min(min(tempMeas)));
t_max = max(max(max(tempMeas)));
t_range = t_max - t_min;
% Define cube size
size_cube = 0.2; % could be based on X Y or Z range(s)
% Get a figure going...
view(3)
axis([0 10 0 10 0 10])
lighting phong
for i = 1:10 % 10 ft(m)
for j = 1:10 %10 ft(m)
for k = 1:10
% Get a coord/measurement from data
x_pos = i;
y_pos = j;
z_pos = k;
temp = tempMeas(i,j,k);
% Figure out the color ...
norm_color = (temp - t_min)/t_range;
if norm_color < 0.25
r_val = 0;
b_val = 1;
g_val = (norm_color)/0.25;
elseif norm_color < 0.50 && norm_color >= 0.25
r_val = 0;
b_val = 1-(norm_color-0.25)/0.25;;
g_val = 1;
elseif norm_color < 0.75 && norm_color >= 0.50
r_val = (norm_color-0.50)/0.25;
b_val = 0;
g_val = 1;
else
r_val = 1;
b_val = 0;
g_val = 1- (norm_color-0.75)/0.25;
end
vertex_matrix = [x_pos-size_cube/2 y_pos-size_cube/2
z_pos-size_cube/2;
x_pos+size_cube/2 y_pos-size_cube/2
z_pos-size_cube/2;
x_pos+size_cube/2 y_pos+size_cube/2
z_pos-size_cube/2;
x_pos-size_cube/2 y_pos+size_cube/2
z_pos-size_cube/2;
x_pos-size_cube/2 y_pos-size_cube/2
z_pos+size_cube/2;
x_pos+size_cube/2 y_pos-size_cube/2
z_pos+size_cube/2;
x_pos+size_cube/2 y_pos+size_cube/2
z_pos+size_cube/2;
x_pos-size_cube/2 y_pos+size_cube/2
z_pos+size_cube/2];
faces_matrix = [1 2 6 5;
2 3 7 6;
3 4 8 7;
4 1 5 8;
1 2 3 4;
5 6 7 8];
patch('Vertices',vertex_matrix,'Faces',faces_matrix,...
'FaceVertexCData',[r_val g_val
b_val],'FaceColor','flat',...
'EdgeColor',[r_val g_val b_val]);
end
end
end
.
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