How to combine 3 xyz data files

Hi,

I have 3 xyz data files (each contains longitude(z), latitude(y), and the water depth(z)). For my assignments, I have to combine these 3 xyz data files together to create a new bathymetry. I have tried the following codes, but matlab just crashed everytime i run it.

%%COMBINE 2014 XYZ DATA FILES
clear all; clc
a=load('bs_09092014_soundings-mean.pts');
b=load('bs_09092014_soundings_shoalest.pts');
c=load('bs_10092014-levels.pts');

% FIND THE MIN AND MAX AMONG THE 3 DATA FILES
% FIND X MIN
if ((min(a(:,1))>min(b(:,1))) && (min(a(:,1))>min(c(:,1))))
    xmin=min(a(:,1));
else
    if ((min(b(:,1))>min(a(:,1))) && (min(b(:,1))>min(c(:,1))))
        xmin=min(b(:,1));
    else 
        xmin=min(c(:,1));
    end
end
% FIND X MAX
if ((max(a(:,1))<max(b(:,1))) && (max(a(:,1))<max(c(:,1))))
    xmax=max(a(:,1));
else
    if ((max(b(:,1))<max(a(:,1))) && (max(b(:,1))<max(c(:,1))))
        xmax=max(b(:,1));
    else
        xmax=max(c(:,1));
    end
end
% FIND Y MIN
if ((min(a(:,2))>min(b(:,2))) && (min(a(:,2))>min(c(:,2))))
    ymin=min(a(:,2));
else
    if ((min(b(:,2))>min(a(:,2))) && (min(b(:,2))>min(c(:,2))))
        ymin=min(b(:,2));
    else
        ymin=min(c(:,2));
    end
end
% FIND Y MAX
if ((max(a(:,2))<max(b(:,2))) && (max(a(:,2))>max(c(:,2))))
    ymax=max(a(:,2));
else
    if ((max(b(:,2))>max(a(:,2))) && (max(b(:,2))>max(c(:,2))))
        ymax=max(b(:,2));
    else
        ymax=max(c(:,2));
    end
end

% FIND THE INDICES BETWEEN XY MIN AND MAX, TO CREATE A NEW MATRIX THAT CONSISTS OF THE INTERSECTIONAL AREA OF ALL 3 XYZ FILES
aInd=find(a(:,1)>xmin & a(:,1)<xmax & a(:,2)>ymin & a(:,2)<ymax);
xa=a(aInd,1);
ya=a(aInd,2);
za=a(aInd,3);

bInd=find(b(:,1)>xmin & b(:,1)<xmax & b(:,2)>ymin & b(:,2)<ymax);
xb=b(bInd,1);
yb=b(bInd,2);
zb=b(bInd,3);

cInd=find(c(:,1)>xmin & c(:,1)<xmax & c(:,2)>ymin & c(:,2)<ymax);
xc=c(cInd,1);
yc=c(cInd,2);
zc=c(cInd,3);

xstep=linspace(xmin,xmax,1000);
ystep=linspace(ymin,ymax,1000);
[xia yia]=meshgrid(xstep,ystep);
zia=griddata(xa,ya,za,xia,yia);
[xib yib]=meshgrid(xstep,ystep);
zib=griddata(xb,yb,zb,xib,yib);
[xic yic]=meshgrid(xstep,ystep)'
zic=griddata(xc,yc,zc,xic,yic);

pcolor(xia,yia,zia);
shading interp
hold on
pcolor(xib,yib,zib);
shading interp
hold on
pcolor(xic,yic,zic);
shading interp
hold off

Thanks, Eve

[Image Analyst]

For a true MATLAB crash (crash of the actual matlab.exe itself, and not just of your particular program), see the FAQ: http://matlab.wikia.com/wiki/FAQ#After_installation.2C_MATLAB_crashes_or_gives_an_error_message_when_I_try_to_run_MATLAB.

Answer 1

[Mohammad Abouali]

Follow this procedure:

1) load your three files into a,b,c variable

2) combine them into one variable:

x=[a(:,1),b(:,1),c(:,1)];
y=[a(:,2),b(:,2),c(:,2)];
z=[a(:,3),b(:,3),c(:,3)];

3) make a scattered intrpolant

F = scatteredInterpolant(x,y,z)

4) make a gridded region with proper spacing of your choice

minX=min(x);
maxX=max(x);

same goes for y; then make a regularly spaced grid:

[XGrid, YGrid]=ndgrid(minX:dx:maxX,minX:dx:maxX);

5) interpolate your data back to this area grid by calling

zGrid=F(XGrid,YGrid);

[eevee]

Hi Mohammad,

Thanks for your help. However, my 3 xyz data files are made up of different matrix size. Which is why I was told by my lecturer to look for the min and max x,y,z values from the intersecpted area of the 3 files. And then, create a new grid with the newly found min max values, and the intercepted z values (please see attached image)

I'm still very confused what is expected from me. I managed to obtain a plot with my code, but it looks more like overlapping these 3 files data more than plotting ONLY the intercepted areas.

Hope to hear from you soon.

Thanks again, Eve

[Mohammad Abouali]

it's fine if they are different size or location. Make sure that x and y are just a big long vector containing all points. Scattered Interpolant will triangulates these points.

[eevee]

Hi Mohammad,

I've tried but MATLAB kept giving me the error message:

x=[a(:,1),b(:,1),c(:,1)];
y=[a(:,2),b(:,2),c(:,2)];
z=[a(:,3),b(:,3),c(:,3)];
Error using horzcat
CAT arguments dimensions are not consistent.

Thanks :)

[Image Analyst]

I just saw your new question: http://www.mathworks.com/matlabcentral/answers/159447-how-to-combine-3-nx3-matrices and I already answered it there. No need to do that. Why do you want to monitor two different threads for answers to the same question. It just makes it more complicated for everyone. Below is the same answer I gave in your duplicate question:

Eve:

They have different numbers of rows. Put these lines before the error:

whos a
whos b
whos c

Tell me what it says in the command window.

[Mohammad Abouali]

sorry instead of

x=[a(:,1) , b(:,1) , c(:,1)];

change it to

x=[a(:,1) ; b(:,1) ; c(:,1)];

do the same with all the others, i.e. y and z.

[eevee]

Thanks! Changes noted! And it's very nice of you to post it on another question tread too!

Thanks a mill!!!

Have a good day ahead!

Eve

[Mohammad Abouali]

You are welcome.

[Charlotte Findlay]

Could I ask what the 'dx' component of this part of the code would be?

[XGrid, YGrid]=ndgrid(minX:dx:maxX,minX:dx:maxX);

Answer 2

[j.D]

Can this code work for two and what changes are needed if it can be used for two