plot data X,y,z data as surface

Question

Chiara Lanzi 2020-6-1

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/539798-plot-data-x-y-z-data-as-surface

评论： Cris LaPierre 2020-6-2

Hi all.

I am trying to plot stress values with matlab. My file dataset is with 3 columns: x_coord, y_coord, stress (which correspond to the stress values).

I tried to use scatter but, obviously, it plot the data as a point which is not exactly what I want.

I used scatterinterpolant+surf and imagesc but the colorbar numbers are different from the real data, so I am not sure I am doing the right thing.

F = scatteredInterpolant(x_axis, y_axis,zvalue);
min_x_axis = min(x_axis);
min_y_axis = min(y_axis);
max_x_axis = max(x_axis);
max_y_axis = max(y_axis);
x= linspace(min_x_axis, max_x_axis, 100);
y = linspace(min_y_axis, max_y_axis, 100);
[X, Y] = ndgrid(x, y);
D = F(X, Y);
surf(X, Y, D, 'edgecolor', 'none'); 

Thanks to all who can help me.

2 个评论
显示无隐藏无

KSSV 2020-6-1

Attach your data.

Chiara Lanzi 2020-6-1

data.txt

Here the data

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Cris LaPierre 2020-6-1

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/539798-plot-data-x-y-z-data-as-surface#answer_444507

Your code looks good. How exact are you expecting the colorbar to be? You've interpolated the data, so it's not going to exactly match.

4 个评论
显示 2更早的评论隐藏 2更早的评论

Chiara Lanzi 2020-6-2

Thank you!!!!Using 1000 for the grid I can see a very good improvement.

I didn't think that the grid was the problem or that it can affect so much the result. Well,now I know!!

Thank you, again.

Cris LaPierre 2020-6-2

在 MATLAB Online 中打开

Just one follow up then. Your grid does not have to be equally spaced. Most of this surface can be generated with only a few points. You really only need the grid to be finer around your points of interest. If you can get the grid to exactly land on your extreme points, you can get the same max/min values.

min_x_axis = -50000
max_x_axis = 4.9936e+04
min_y_axis = -5.0000e+04
max_y_axis = 0
min_zvalue = -16.2749
max_zvalue = 1.5124

I created a scatter3 plot and used the data tip tool to identify the X and Y coordinates of the peaks. I added those to the 100x100 grid and got the same max/min values.

...
x= linspace(min_x_axis, max_x_axis); % default is 100 points
y = linspace(min_y_axis, max_y_axis);
% Add points of interest to the grid
x = sort([x -4300 0 4273])
y = sort([y -10400 -10000 -9982 -9600 -5000 0])
.
.
.

And the corresponding min/max values of the surface

min_X = -50000
max_X = 4.9936e+04
min_Y = -5.0000e+04
max_Y = 0
min_D = -16.2465
max_D = 1.5124

Of course, this is a manual process.

One item to be aware of still. The bump on the top is actually 2 separate peaks. I can see this when I explore the scatter3 plot. However, I could not get it to appear in the surface, again likely due to approximation errors when interpolating.