Boundary and smooth the figure

I have a very larg data (X, Y, Z) and I used some codes to read the data then remove the columns that contain NaN. The below codes are used after the previous description to plot a 2D graph or 3D with Z being indicated by colors. I tried pcolor and surf but I'm getting the same two problems; 1- the figure is supposed to be perfect x-shape with an angle of 30, but in the middle some portions are connected together which is incorrect. 2- I'm looking for a way to smooth the figure in which the portions where high value of Z be distributed somehow on the adjacent points so that it can be very clear that at this location we have high value of Z (i.e., in my plots this high Z value is showing as a point). I hope that someone can help me doing this. Thanks in advance

x0 = min(x) ; x1 = max(x) ; 
y0 = min(y) ; y1 = max(y) ; 
xi = linspace(x0,x1,150) ; 
yi = linspace(y0,y1,150) ; 
[X,Y] = meshgrid(xi,yi) ;
Z = griddata(x,y,z,X,Y) ;

% Get boundary coordinates 

idx = boundary(x,y) ; 
xb = x(idx) ; yb = y(idx) ; 
% Get points lying inside the boundary 
idx = inpolygon(X,Y,xb,yb) ;
Z(~idx) = NaN ;

f=pcolor(X,Y,Z);

colorbar
shading interp 
axis('equal')

[Mathieu NOE]

hello again !

seems we have already addressed the same topic here :

smooth the surf or pcolor graph - MATLAB Answers - MATLAB Central (mathworks.com)

[Abdulkarim Almukdad]

Yes. however, in this case I was having another issue which is the boundary as you can see from the figure there are portions where the figure is connected at the corners eventhough I'm using the boundary function. Do you have any better functions or codes to solve this? and please ignore the smoothing problem as you have already solved that.

Thanks in advance

[Mathieu NOE]

you mean, you would like to remove the orange triangles ?

[Abdulkarim Almukdad]

exactly

[Mathieu NOE]

ok , so do you have the data that comes with the code ?

[Abdulkarim Almukdad]

yes, please find attached the data

[Mathieu NOE]

I was not 100 % successful this time

I increased the "shrink" factor (in the boundary function) so that the triangular areas are reduced but they did not completely vanished

I tried a couple of other approaches but without much benefit

I believe I have to find a robust way to introduce a couple of more points to create the missing corner of the boundary

clc
close all
clear all

num = readtable("01)30.xlsx") ; 
 
% Take all the data under each variable name
x=num{1:1:end, contains(num.Properties.VariableNames, 'x')};
y=num{1:1:end, contains(num.Properties.VariableNames, 'y')};
z=num{1:1:end, contains(num.Properties.VariableNames, 'v')};
% Convert the matrix to 1 column only (scalar)
x=x(:);
y=y(:);
z=z(:);
% Delete rows that contain NaNs with reference to the variable z
i=1; [m,n]=size(x); 
    while i<=m
        
        if isnan(z(i,1))
        x(i,:)=[];
        y(i,:)=[];
        z(i,:)=[];
        i=i-1;      
        end
        i=i+1; [m,n]=size(x);  
        
    end
    
x0 = min(x) ; x1 = max(x) ; 
y0 = min(y) ; y1 = max(y) ; 
xi = linspace(x0,x1,150) ; 
yi = linspace(y0,y1,150) ; 
[X,Y] = meshgrid(xi,yi) ;
Z = griddata(x,y,z,X,Y) ;
% Get boundary coordinates 
idx = boundary(x,y,1) ; 
xb = x(idx) ; yb = y(idx) ; 

a = 0.5;
nd = [a a]/2;
dd = [1 -1+a];

xxb = filtfilt(nd,dd,xb);
yyb = filtfilt(nd,dd,yb);

figure(1),
plot(xb,yb,'*-b',xxb,yyb,'r');

% Get points lying inside the boundary 
% idx = inpolygon(X,Y,xb,yb) ;
idx = inpolygon(X,Y,xxb,yyb) ;
Z(~idx) = NaN ;
figure(2),
f=pcolor(X,Y,Z);
colorbar
shading interp 
axis('equal')

[Abdulkarim Almukdad]

Thank you very much for your help. I think I have an idea that might solve this issue but I have zero knowledge about how to do it on matlab unfortunately. I think if the data of each side of the x is ploted and found its boundary, then the combination of both boundaries can do the job. I will try to separate the sides from excel manually by checking each column from simple plottings then I will check what will happen in matlab.