MATLAB: How to make a curve line through data points on surface 3D (curve line fitting in 3D)

curve line fitting in 3d

Dear everyone,

I have a suface 3D in matlab. I want to build a curve line through data points (A, B, C, D) in this surface. I think this is the curve line fitting of surface. I try to do that but I couldn't obtain result. Please Help me for this.

The code is showed below.

Many thanks,

Best regard.

clear all;
clc;
x1 = [10,11,12,10,11,12,10,11,12,10,11,12];
x2 = [60,60,60,70,70,70,80,80,80,90,90,90];
Profit = [133.355, 151.273, 143.703, 201.625, 218.227, 209.948, 219.271, 246.907, 233.791, 215.890, 246.132, 228.042];
xv = 10:0.1:12;
yv =60:1:90;
[X,Y] = ndgrid(xv, yv);
Z = griddata(x1, x2, Profit, X, Y, 'cubic');
figure
surf(X,Y,Z)
grid on
 hold on
A=scatter3(x1(8),x2(8),Profit(8),'filled','MarkerFaceColor', 'y')
B=scatter3(x1(2),x2(2),Profit(2),'filled','MarkerFaceColor', 'y')
C=scatter3(x1(5),x2(5),Profit(5),'filled','MarkerFaceColor', 'y')
D=scatter3(x1(11),x2(11),Profit(11),'filled','MarkerFaceColor', 'y')
xlabel('Скорость, м/с'), ylabel('Грузоподъемность, т'), zlabel('Profit, 10^4*$')
view(-120,47)

Best Answer

Try this solution

x0 = x1([8 2 5 11]);
y0 = x2([8 2 5 11]);
yy = linspace(min(y0),max(y0),20);
xx = interp1(y0,x0,yy);
zz = interp2(X',Y',Z',xx,yy);
line(xx,yy,zz,'linew',2)

result

Related Solutions

MATLAB: How to display the contour line values from a contour plot generated using the curve fitting tools

If, in the auto-generated code from the gui you specify h (the handler to the plots) as an aditional output variable you can access those data.

    function [fitresult, gof, h] = createFit(x, y, z)
    %CREATEFIT(X,Y,Z)
    %  Create a fit.
    %


    %  Data for 'untitled fit 1' fit:
    %      X Input : x
    %      Y Input : y
    %      Z Output: z
    %  Output:
    %      fitresult : a fit object representing the fit.
    %      gof : structure with goodness-of fit info.
    %
    %  See also FIT, CFIT, SFIT.
    %  Auto-generated by MATLAB on 28-Apr-2017 12:52:15
    %%Fit: 'untitled fit 1'.
    [xData, yData, zData] = prepareSurfaceData( x, y, z );
    % Set up fittype and options.
    ft = fittype( 'lowess' );
    % Fit model to data.
    [fitresult, gof] = fit( [xData, yData], zData, ft, 'Normalize', 'on' );
    % Make contour plot.
    figure( 'Name', 'untitled fit 1' );
    h = plot( fitresult, [xData, yData], zData, 'Style', 'Contour' );
    legend( h, 'untitled fit 1', 'z vs. x, y', 'Location', 'NorthEast' );
    % Label axes
    xlabel x
    ylabel y
    grid on

h is an array and you have to guess which component is the one for the contour plot. In my example it was h(1). That component is the same as in [C, h] = contour(...), and you can use it in the same way. h(1).ContourMatrix has the matrix C that contour would output, and, in particular you can write

clabel(h(1).ContourMatrix, h(1))

to have the contour lines of your plot labelled.

MATLAB: Fitting a smooth curve

Curve Fitting Tool should do it for you:

x=[203.0173 275.3912 331.9024 387.4221];  
y=[-195.6477 -244.2275 -222.4161 -173.8364];
%%below from here requires and comes from Curve Fitting Toolbox
[xData, yData] = prepareCurveData( x, y );
ft = fittype( 'poly3' );
[fitresult, gof] = fit( xData, yData, ft );
figure( 'Name', 'Fitted Model' );
h = plot( fitresult, xData, yData );
legend( h, 'y vs. x', 'Fitted Model', 'Location', 'NorthEast' );
xlabel x
ylabel y
grid on

You can reach the fitted model(3rd in this case) by typing

fitresult

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