How to I make the colorbar stay attributed to the original scatter plot after adding a plane.

The following graph (first set of code) would look much better with the plane (in the second code) however when I plot them at the same time I loose the color bar for the scatter3 plot. Is there anyway I can prioritise the scatter data for the colormap? Thanks to anyone who can help :)

First plot

close all;

clear all;

hold on;

grid on;

x = [2.25

2.67

1.72

2.17

2.53

2.99

1

1.5

1.5

2

2

0.72

0.82

1.35

1.85];

z = [2891.969195

3346.172988

2354.307823

2821.188445

3210.73036

3667.803167

1694.915086

2025.363097

2336.802294

2644.227461

2886.362509

807.9313207

998.594554

1918.290754

3245.607366];

y = [1.76

2.36

1.27

1.74

2.21

2.72

1

1

1.5

1.5

2

0.7

0.82

1.11

1.38];

mu = [25.9

36.0

15.6

24.2

32.5

44.7

5.7

12.1

12.1

20.7

20.7

3.2

4.0

9.9

17.9];

% Create 3D scatter plot, colorcode the values based on mu values

scatter3(x,y,z, 40, mu, 'filled')

xlabel('Cold Flow (l/min)')

ylabel('Hot Flow (l/min)')

zlabel('Heat Transfer Coefficient (W/m^2k)')

% equate aspect ratio (if needed)

%axis equal

colormap jet

% Add colorbar if desired

cb = colorbar();

title(cb, 'Pressure Drop (mbar)')

hold on

x2 = [0.5

1

1.5

2

2.5

3

0.5

1

1.5

2

2.5

3

0.5

1

1.5

2

2.5

3

0.5

1

1.5

2

2.5

3

0.5

1

1.5

2

2.5

3

0.5

1

1.5

2

2.5

3];

y2 = [0.5

0.5

0.5

0.5

0.5

0.5

1

1

1

1

1

1

1.5

1.5

1.5

1.5

1.5

1.5

2

2

2

2

2

2

2.5

2.5

2.5

2.5

2.5

2.5

3

3

3

3

3

3];

z2 = [1285.465043

1652.954367

1870.63867

2021.18615

2133.954576

2222.745474

1463.660465

1959.756944

2273.415694

2499.69403

2674.486749

2815.441768

1551.18987

2119.923198

2491.810631

2766.276182

2981.947056

3158.241579

1605.492757

2222.664148

2634.97716

2943.842119

3189.317721

3391.81713

1643.266028

2295.721063

2738.282674

3073.380734

3341.920437

3564.939405

1671.421298

2351.049288

2817.366469

3173.358014

3460.469185

3700.158609];

scatter3(x2,y2,z2,10,'filled')

Second plot

close all;

clear all;

hold on;

grid on;

x = [2.25

2.67

1.72

2.17

2.53

2.99

1

1.5

1.5

2

2

0.72

0.82

1.35

1.85];

z = [2891.969195

3346.172988

2354.307823

2821.188445

3210.73036

3667.803167

1694.915086

2025.363097

2336.802294

2644.227461

2886.362509

807.9313207

998.594554

1918.290754

3245.607366];

y = [1.76

2.36

1.27

1.74

2.21

2.72

1

1

1.5

1.5

2

0.7

0.82

1.11

1.38];

mu = [25.9

36.0

15.6

24.2

32.5

44.7

5.7

12.1

12.1

20.7

20.7

3.2

4.0

9.9

17.9];

% Create 3D scatter plot, colorcode the values based on mu values

scatter3(x,y,z, 40, mu, 'filled')

xlabel('Cold Flow (l/min)')

ylabel('Hot Flow (l/min)')

zlabel('Heat Transfer Coefficient (W/m^2k)')

% equate aspect ratio (if needed)

%axis equal

colormap jet

% Add colorbar if desired

cb = colorbar();

title(cb, 'Pressure Drop (mbar)')

hold on

x2 = [0.5

1

1.5

2

2.5

3

0.5

1

1.5

2

2.5

3

0.5

1

1.5

2

2.5

3

0.5

1

1.5

2

2.5

3

0.5

1

1.5

2

2.5

3

0.5

1

1.5

2

2.5

3];

y2 = [0.5

0.5

0.5

0.5

0.5

0.5

1

1

1

1

1

1

1.5

1.5

1.5

1.5

1.5

1.5

2

2

2

2

2

2

2.5

2.5

2.5

2.5

2.5

2.5

3

3

3

3

3

3];

z2 = [1285.465043

1652.954367

1870.63867

2021.18615

2133.954576

2222.745474

1463.660465

1959.756944

2273.415694

2499.69403

2674.486749

2815.441768

1551.18987

2119.923198

2491.810631

2766.276182

2981.947056

3158.241579

1605.492757

2222.664148

2634.97716

2943.842119

3189.317721

3391.81713

1643.266028

2295.721063

2738.282674

3073.380734

3341.920437

3564.939405

1671.421298

2351.049288

2817.366469

3173.358014

3460.469185

3700.158609];

%scatter3(x2,y2,z2,10,'filled')

tri = delaunay(x2,y2);

trisurf(tri, x2, y2, z2,'FaceColor','r', 'edgecolor', 'none','FaceAlpha', [0.3]);

[dpb]

reformat the Q? so is legible -- too much data to list in line; attach as .mat file instead..or dynamically generate example with code.

[dpb]

Given the formatting didn't try to run/download but colormap applies to the axes object or specific other graphics objects that have a 'Colormap' property -- which scatter3 doesn't.

I think you'll have to use two axes here and plot each into its own then set the colormap to the axes containing the scatter plot.

Answer 1

[Gautam]

Hello Imogen,

I understand that you want the “Colormap” to map only the range of values represented by the scatter plot and not consider the plane and for that you want the “Colormap” to prioritize only the data of the scatter plot.

However, since, in this case, the “Colormap” property is of the “Axes” object and not the “Scatter” object, it is not possible to have the colormap correspond only to the scatterplot.

One possible workaround for this is to adjust the data values that map to the first and last color of the “Colormap” respectively. You can do this by adjusting the “CLim” property of the “Axes”. For that, you can create a “Scatter” object corresponding to your scatter plot modifying the line that used the “scatter3()” function as

scatplot = scatter3(x,y,z, 40, mu, 'filled'); 

Set the “CLim” property of the parent “Axes” by adding the following lines at the end of your code

ax = scatplot.Parent; 
cmap = colormap('jet'); 
ax.CLim = [min(mu) max(mu)]; 

This gives the output as shown in the figure below

For more information on the “Axes Properties”, refer to the “Color and Transparency” section of the MathWorks documentation page on “Axes Properties”. I am attaching the link below for your convenience.

1. Axes Properties: https://www.mathworks.com/help/releases/R2021a/matlab/ref/matlab.graphics.axis.axes-properties.html?searchHighlight=axes%20properties&s_tid=doc_srchtitle

Thank You,

Gautam Murthy