creat a grid from xyz file

Hi!

I have a file of X,Y,Z values (X,Y are cartesian coordinates) and Z the altitude (it's a topo-bathymetry file).

can you tell me please how to creat a grid which contains this altitudes .

thank you

Answer 1

[jonas]

%make a 100x100 grid
[XX,YY] = meshgrid(linspace(min(X),max(X),100),linspace(min(Y),max(Y),100))
%interpolate Z data to grid
ZZ = griddata(X,Y,Z,XX,YY)

[wassim boulala]

yes thank you but how to visualized the result in a figure .

best,

[jonas]

surf(XX, YY, ZZ)

[wassim boulala]

it seems to have an error.

in my file the size of X Y and Z is 8630. but when I use code its gives me a grid with 8630 X 8630. so it's not logical.

best,

[jonas]

Probably you made a mistake, because the code works for me. Upload the data or provide some more information if you want more help.

[wassim boulala]

here's my code

clear;
%open file  xyz 
T=readtable('points.txt')
A=T{:,:}
X=A(:,1);
Y=A(:,2);
Z=A(:,3);
n=length(X);
%make a nxn grid
[XX,YY] = meshgrid(linspace(min(X),max(X),n),linspace(min(Y),max(Y),n));
%interpolate Z data to grid
ZZ = griddata(X,Y,Z,XX,YY);
surf(XX,YY,ZZ)

[jonas]

n is the resolution of the grid. Use a lower value like 100. However, you should get an OK graph anyway?

[wassim boulala]

how can i do a graph in 2D (X,Y) ?

i think that works.

[jonas]

Sorry, but this is waste of time. I'll respond when you ask a coherent question.