Smoothing 3D surface plot and its color gradient

I am currently facing trouble replicating the attached figure.

In specific, I am facing difficulties in achieving a seamless 3D surface plot, as well as its transitioning from discrete to continuous color gradients. In my efforts to smooth the surface, I have tried with increasing the data point density and interpolations to enhance its smoothness. But it yielded a somewhat jagged effect. Same goes to the color scale.

Any assistance in resolving these issues would be highly appreciated.

filename = 'Data.csv';
data = readmatrix(filename);

x = data(:, 1);
y = data(:, 2);
z = data(:, 3);

% Create a mesh grid for X and Y
[X, Y] = meshgrid(x, y);

% Create a mesh grid for Z
Z = meshgrid(z);

% Add a vertical line at z = 0 by making a mesh grid
Z0 = zeros(size(X));

% 3D surface plot
figure;
set(gcf, 'Color', [1, 1, 1]);
surf(X, Y, Z, 'EdgeColor', 'none');

lineColors = [...
90, 0, 9
120, 25, 7
157, 56, 10
187, 97, 45
202, 129, 88
216, 163, 131
231, 198, 179
255, 255, 255
191, 215, 227
132, 180, 203
75, 143, 180
25, 107, 154
3, 75, 133
2, 47, 115
1, 18, 98
]./255;

vik = interp1(1:max(size(lineColors)),lineColors,1:(1/4):max(length(lineColors)));
colormap(flipud(vik));
% colorbar;
caxis([-0.6, 1]);

% X-axis limits to match data
xlim([min(x), max(x)]);
ylim([-2, 2]);

hold on;

% Add a grey section
surf(X, Y, Z0, 'EdgeColor', 'none', 'FaceColor', [0.5, 0.5, 0.5], 'FaceAlpha', 0.2);
hold off;

% Remove gridlines, axis labels, and tick marks for y and z axes
grid off;
set(gca, 'YTick', []);
set(gca, 'ZTick', []);
set(gca, 'YColor', 'none');
set(gca, 'ZColor', 'none');
grid on;
set(gca, 'GridColor', [0.5, 0.5, 0.5]);

Answer 1

[Star Strider]

Experiment with the daspect function —

filename = 'Data.csv';
data = readmatrix(filename);

x = data(:, 1);
y = data(:, 2);
z = data(:, 3);

% Create a mesh grid for X and Y
[X, Y] = meshgrid(x, y);

% Create a mesh grid for Z
Z = meshgrid(z);

% Add a vertical line at z = 0 by making a mesh grid
Z0 = zeros(size(X));

% 3D surface plot
figure;
set(gcf, 'Color', [1, 1, 1]);
surf(X, Y, Z, 'EdgeColor', 'none');

lineColors = [...
90, 0, 9
120, 25, 7
157, 56, 10
187, 97, 45
202, 129, 88
216, 163, 131
231, 198, 179
255, 255, 255
191, 215, 227
132, 180, 203
75, 143, 180
25, 107, 154
3, 75, 133
2, 47, 115
1, 18, 98
]./255;

vik = interp1(1:max(size(lineColors)),lineColors,1:(1/4):max(length(lineColors)));
colormap(flipud(vik));
% colorbar;
caxis([-0.6, 1]);

% X-axis limits to match data
xlim([min(x), max(x)]);
ylim([-2, 2]);

hold on;

% Add a grey section
surf(X, Y, Z0, 'EdgeColor', 'none', 'FaceColor', [0.5, 0.5, 0.5], 'FaceAlpha', 0.2);
hold off;

% Remove gridlines, axis labels, and tick marks for y and z axes
grid off;
set(gca, 'YTick', []);
set(gca, 'ZTick', []);
set(gca, 'YColor', 'none');
set(gca, 'ZColor', 'none');
grid on;
set(gca, 'GridColor', [0.5, 0.5, 0.5]);
daspect([10 1 1])                                                                   % <— ADDED

It changes the aspect ratio of the plot axes.

.

[Hariharan Siva]

Awesome! Thank you for your assistance—it worked perfectly. By the way, anything for the color gradient?

[Star Strider]

Thank you!

As always, my pleasure!

I am not certain what you mean by ‘color gradient’. One option might be to use the FaceColor property in the first surf call, specifically adding 'FaceColor','interp' to get smooth transitions, although I am not certain if that would add anything to your already specifying 'EdgeColor','none' (although you could also change that to 'EdgeColor','interp', probably producing the same effect).

.

[Hariharan Siva]

Perfect! This is exactly what I was looking for. 😍 Thank you once again!

[Star Strider]

As always, my pleasure!