1  %'proj_grid': project fields with unstructured coordinantes on a regular grid


2  % 


3  % function [A,rangx,rangy]=proj_grid(vec_X,vec_Y,vec_A,rgx_in,rgy_in,npxy_in)


4 


5  %=======================================================================


6  % Copyright 20082021, LEGI UMR 5519 / CNRS UGA GINP, Grenoble, France


7  % http://www.legi.grenobleinp.fr


8  % Joel.Sommeria  Joel.Sommeria (A) legi.cnrs.fr


9  %


10  % This file is part of the toolbox UVMAT.


11  %


12  % UVMAT is free software; you can redistribute it and/or modify


13  % it under the terms of the GNU General Public License as published


14  % by the Free Software Foundation; either version 2 of the license,


15  % or (at your option) any later version.


16  %


17  % UVMAT is distributed in the hope that it will be useful,


18  % but WITHOUT ANY WARRANTY; without even the implied warranty of


19  % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the


20  % GNU General Public License (see LICENSE.txt) for more details.


21  %=======================================================================


22 


23  function [A,rangx,rangy]=proj_grid(vec_X,vec_Y,vec_A,rgx_in,rgy_in,npxy_in)


24  if length(vec_Y)<2


25  msgbox_uvmat('ERROR','less than 2 points in proj_grid.m');


26  return;


27  end


28  diffy=diff(vec_Y); %difference dy=vec_Y(i+1)vec_Y(i)


29  index=find(diffy);% find the indices of vec_Y after wich a change of horizontal line occurs(diffy non zero)


30  if isempty(index); msgbox_uvmat('ERROR','points aligned along abscissa in proj_grid.m'); return; end;%points aligned% A FAIRE: switch to line plot.


31  diff2=diff(diffy(index));% diff2 = fluctuations of the detected vertical grid mesh dy


32  if max(abs(diff2))>0.001*abs(diffy(index(1))) % if max(diff2) is larger than 1/1000 of the first mesh dy


33  % the data are not regularly spaced and must be interpolated on a regular grid


34  if exist('rgx_in','var') & ~isempty (rgx_in) & isnumeric(rgx_in) & length(rgx_in)==2% positions imposed from input


35  rangx=rgx_in; % first and last positions


36  rangy=rgy_in;


37  % npxy=npxy_in;


38  dxy(1)=1/(npxy_in(1)1);%grid mesh in y


39  dxy(2)=1/(npxy_in(2)1);%grid mesh in x


40  dxy(1)=(rangy(2)rangy(1))/(npxy_in(1)1);%grid mesh in y


41  dxy(2)=(rangx(2)rangx(1))/(npxy_in(2)1);%grid mesh in x


42  else % interpolation grid automatically determined


43  rangx(1)=min(vec_X);


44  rangx(2)=max(vec_X);


45  rangy(2)=min(vec_Y);


46  rangy(1)=max(vec_Y);


47  dxymod=sqrt((rangx(2)rangx(1))*(rangy(1)rangy(2))/length(vec_X));


48  dxy=[dxymod/4 dxymod/4];% increase the resolution 4 times


49  end


50  xi=[rangx(1):dxy(2):rangx(2)];


51  yi=[rangy(1):dxy(1):rangy(2)];


52  [XI,YI]=meshgrid(xi,yi);% creates the matrix of regular coordinates


53  A=griddata_uvmat(vec_X,vec_Y,vec_A,xi,yi');


54  A=reshape(A,length(yi),length(xi));


55  else


56  x=vec_X(1:index(1));% the set of abscissa (obtained on the first line)


57  indexend=index(end);% last vector index of line change


58  ymax=vec_Y(indexend+1);% y coordinate AFTER line change


59  ymin=vec_Y(index(1));


60  %y=[vec_Y(index) ymax]; % the set of y ordinates including the last one


61  y=vec_Y(index);


62  y(length(y)+1)=ymax;


63  nx=length(x); %number of grid points in x


64  ny=length(y); % number of grid points in y


65  B=(reshape(vec_A,nx,ny))'; %vec_A reshaped as a rectangular matrix


66  [X,Y]=meshgrid(x,y);% positions X and Y also reshaped as matrix


67 


68  %linear interpolation to improve the image resolution and/or adjust


69  %to prescribed positions


70  test_interp=1;


71  if exist('rgx_in','var') & ~isempty (rgx_in) & isnumeric(rgx_in) & length(rgx_in)==2% positions imposed from input


72  rangx=rgx_in; % first and last positions


73  rangy=rgy_in;


74  npxy=npxy_in;


75  else


76  rangx=[vec_X(1) vec_X(nx)];% first and last position found for x


77  % rangy=[ymin ymax];


78  rangy=[max(ymax,ymin) min(ymax,ymin)];


79  if max(nx,ny) <= 64 & isequal(npxy_in,'np>256')


80  npxy=[8*ny 8*nx];% increase the resolution 8 times


81  elseif max(nx,ny) <= 128 & isequal(npxy_in,'np>256')


82  npxy=[4*ny 4*nx];% increase the resolution 4 times


83  elseif max(nx,ny) <= 256 & isequal(npxy_in,'np>256')


84  npxy=[2*ny 2*nx];% increase the resolution 2 times


85  else


86  npxy=[ny nx];


87  test_interp=0; % no interpolation done


88  end


89  end


90  if test_interp==1%if we interpolate


91  xi=[rangx(1):(rangx(2)rangx(1))/(npxy(2)1):rangx(2)];


92  yi=[rangy(1):(rangy(2)rangy(1))/(npxy(1)1):rangy(2)];


93  [XI,YI]=meshgrid(xi,yi);


94  A = interp2(X,Y,B,XI,YI);


95  else %no interpolation for a resolution higher than 256


96  A=B;


97  XI=X;


98  YI=Y;


99  end


100  end

