How to turn my [X,Y,Z] into stl using surf2stl?

Hello,

I have made my 3D coordinates, and I have downloaded the surf2stl package example (will put It below). However, for the life of my I don't understand how to use it and I can't find any tutorials online. Any help will be appreciated.

Omar

function surf2stl(filename,x,y,z,mode)
%SURF2STL   Write STL file from surface data.
%   SURF2STL('filename',X,Y,Z) writes a stereolithography (STL) file
%   for a surface with geometry defined by three matrix arguments, X, Y
%   and Z.  X, Y and Z must be two-dimensional arrays with the same size.
%
%   SURF2STL('filename',x,y,Z), uses two vector arguments replacing
%   the first two matrix arguments, which must have length(x) = n and
%   length(y) = m where [m,n] = size(Z).  Note that x corresponds to
%   the columns of Z and y corresponds to the rows.
%
%   SURF2STL('filename',dx,dy,Z) uses scalar values of dx and dy to
%   specify the x and y spacing between grid points.
%
%   SURF2STL(...,'mode') may be used to specify the output format.
%
%     'binary' - writes in STL binary format (default)
%     'ascii'  - writes in STL ASCII format
%
%   Example:
%
%     surf2stl('test.stl',1,1,peaks);
%
%   See also SURF.
%
%   Author: Bill McDonald, 02-20-04

error(nargchk(4,5,nargin));

if (ischar(filename)==0)
    error( 'Invalid filename');
end

if (nargin < 5)
    mode = 'binary';
elseif (strcmp(mode,'ascii')==0)
    mode = 'binary';
end

if (ndims(z) ~= 2)
    error( 'Variable z must be a 2-dimensional array' );
end

if any( (size(x)~=size(z)) | (size(y)~=size(z)) )

      % size of x or y does not match size of z

      if ( (length(x)==1) & (length(y)==1) )
          % Must be specifying dx and dy, so make vectors
          dx = x;
          dy = y;
          x = ((1:size(z,2))-1)*dx;
          y = ((1:size(z,1))-1)*dy;
      end

      if ( (length(x)==size(z,2)) & (length(y)==size(z,1)) )
          % Must be specifying vectors
          xvec=x;
          yvec=y;
          [x,y]=meshgrid(xvec,yvec);
      else
          error('Unable to resolve x and y variables');
      end

end

if strcmp(mode,'ascii')
    % Open for writing in ascii mode
    fid = fopen(filename,'w');
else
    % Open for writing in binary mode
    fid = fopen(filename,'wb+');
end

if (fid == -1)
    error( sprintf('Unable to write to %s',filename) );
end

title_str = sprintf('Created by surf2stl.m %s',datestr(now));

if strcmp(mode,'ascii')
    fprintf(fid,'solid %s\r\n',title_str);
else
    str = sprintf('%-80s',title_str);    
    fwrite(fid,str,'uchar');         % Title
    fwrite(fid,0,'int32');           % Number of facets, zero for now
end

nfacets = 0;

for i=1:(size(z,1)-1)
    for j=1:(size(z,2)-1)

          p1 = [x(i,j)     y(i,j)     z(i,j)];
          p2 = [x(i,j+1)   y(i,j+1)   z(i,j+1)];
          p3 = [x(i+1,j+1) y(i+1,j+1) z(i+1,j+1)];
          val = local_write_facet(fid,p1,p2,p3,mode);
          nfacets = nfacets + val;

          p1 = [x(i+1,j+1) y(i+1,j+1) z(i+1,j+1)];
          p2 = [x(i+1,j)   y(i+1,j)   z(i+1,j)];
          p3 = [x(i,j)     y(i,j)     z(i,j)];        
          val = local_write_facet(fid,p1,p2,p3,mode);
          nfacets = nfacets + val;

      end
  end

if strcmp(mode,'ascii')
    fprintf(fid,'endsolid %s\r\n',title_str);
else
    fseek(fid,0,'bof');
    fseek(fid,80,'bof');
    fwrite(fid,nfacets,'int32');
end

fclose(fid);

disp( sprintf('Wrote %d facets',nfacets) );

% Local subfunctions

function num = local_write_facet(fid,p1,p2,p3,mode)

if any( isnan(p1) | isnan(p2) | isnan(p3) )
    num = 0;
    return;
else
    num = 1;
    n = local_find_normal(p1,p2,p3);

      if strcmp(mode,'ascii')

          fprintf(fid,'facet normal %.7E %.7E %.7E\r\n', n(1),n(2),n(3) );
          fprintf(fid,'outer loop\r\n');        
          fprintf(fid,'vertex %.7E %.7E %.7E\r\n', p1);
          fprintf(fid,'vertex %.7E %.7E %.7E\r\n', p2);
          fprintf(fid,'vertex %.7E %.7E %.7E\r\n', p3);
          fprintf(fid,'endloop\r\n');
          fprintf(fid,'endfacet\r\n');

      else

          fwrite(fid,n,'float32');
          fwrite(fid,p1,'float32');
          fwrite(fid,p2,'float32');
          fwrite(fid,p3,'float32');
          fwrite(fid,0,'int16');  % unused

      end

end

function n = local_find_normal(p1,p2,p3)

v1 = p2-p1;
v2 = p3-p1;
v3 = cross(v1,v2);
n = v3 ./ sqrt(sum(v3.*v3));

Answer 1

[Walter Roberson]

Example:

[X, Y] = meshgrid( linspace(0, 2, 20), linspace(-pi, pi, 15));
Z = sqrt(X) .* cos(Y);
surf2stl('testit.stl', X, Y, Z);

[Abdulaziz Abutunis]

Hi Walter,

I hope all is well.

I have x,y ,z data. The data represent 3D geometry. it is like the geometry is built in layers. So Z is repeated at each layer that builds the geometry. I wonder if I still can use meshgrid or any other way to convert it to an STL file. The reason for converting to STL file is because I want to calculate volume using volume(mesh).

Thanks

Aziz

Answer 2

[Alan Andonian]

I downloaded the file from here:

https://www.mathworks.com/matlabcentral/fileexchange/4512-surf2stl

Then I unziped the file to get the .m file and I put it in the folder I was going to use.

Then I made a live script in the folder with the .m file that I downloaded.

I copy pasted the example:

[X, Y] = meshgrid( linspace(0, 2, 20), linspace(-pi, pi, 15));
Z = sqrt(X) .* cos(Y);
surf2stl('testit.stl', X, Y, Z);

In the folder the .stl apeared. Attached is the screenshot of the STL.