1 | %'proj_grid': project fields with unstructured coordinantes on a regular grid
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2 | % -------------------------------------------------------------------------
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3 | % function [A,rangx,rangy]=proj_grid(vec_X,vec_Y,vec_A,rgx_in,rgy_in,npxy_in)
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4 |
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5 | %=======================================================================
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6 | % Copyright 2008-2020, LEGI UMR 5519 / CNRS UGA G-INP, Grenoble, France
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7 | % http://www.legi.grenoble-inp.fr
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8 | % Joel.Sommeria - Joel.Sommeria (A) legi.cnrs.fr
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9 | %
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10 | % This file is part of the toolbox UVMAT.
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11 | %
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12 | % UVMAT is free software; you can redistribute it and/or modify
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13 | % it under the terms of the GNU General Public License as published
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14 | % by the Free Software Foundation; either version 2 of the license,
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15 | % or (at your option) any later version.
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16 | %
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17 | % UVMAT is distributed in the hope that it will be useful,
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18 | % but WITHOUT ANY WARRANTY; without even the implied warranty of
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19 | % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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20 | % GNU General Public License (see LICENSE.txt) for more details.
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21 | %=======================================================================
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22 |
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23 | function [A,rangx,rangy]=proj_grid(vec_X,vec_Y,vec_A,rgx_in,rgy_in,npxy_in)
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24 | if length(vec_Y)<2
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25 | msgbox_uvmat('ERROR','less than 2 points in proj_grid.m');
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26 | return;
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27 | end
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28 | diffy=diff(vec_Y); %difference dy=vec_Y(i+1)-vec_Y(i)
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29 | index=find(diffy);% find the indices of vec_Y after wich a change of horizontal line occurs(diffy non zero)
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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.
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31 | diff2=diff(diffy(index));% diff2 = fluctuations of the detected vertical grid mesh dy
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32 | if max(abs(diff2))>0.001*abs(diffy(index(1))) % if max(diff2) is larger than 1/1000 of the first mesh dy
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33 | % the data are not regularly spaced and must be interpolated on a regular grid
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34 | if exist('rgx_in','var') & ~isempty (rgx_in) & isnumeric(rgx_in) & length(rgx_in)==2% positions imposed from input
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35 | rangx=rgx_in; % first and last positions
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36 | rangy=rgy_in;
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37 | % npxy=npxy_in;
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38 | dxy(1)=1/(npxy_in(1)-1);%grid mesh in y
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39 | dxy(2)=1/(npxy_in(2)-1);%grid mesh in x
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40 | dxy(1)=(rangy(2)-rangy(1))/(npxy_in(1)-1);%grid mesh in y
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41 | dxy(2)=(rangx(2)-rangx(1))/(npxy_in(2)-1);%grid mesh in x
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42 | else % interpolation grid automatically determined
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43 | rangx(1)=min(vec_X);
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44 | rangx(2)=max(vec_X);
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45 | rangy(2)=min(vec_Y);
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46 | rangy(1)=max(vec_Y);
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47 | dxymod=sqrt((rangx(2)-rangx(1))*(rangy(1)-rangy(2))/length(vec_X));
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48 | dxy=[-dxymod/4 dxymod/4];% increase the resolution 4 times
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49 | end
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50 | xi=[rangx(1):dxy(2):rangx(2)];
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51 | yi=[rangy(1):dxy(1):rangy(2)];
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52 | [XI,YI]=meshgrid(xi,yi);% creates the matrix of regular coordinates
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53 | A=griddata_uvmat(vec_X,vec_Y,vec_A,xi,yi');
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54 | A=reshape(A,length(yi),length(xi));
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55 | else
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56 | x=vec_X(1:index(1));% the set of abscissa (obtained on the first line)
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57 | indexend=index(end);% last vector index of line change
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58 | ymax=vec_Y(indexend+1);% y coordinate AFTER line change
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59 | ymin=vec_Y(index(1));
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60 | %y=[vec_Y(index) ymax]; % the set of y ordinates including the last one
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61 | y=vec_Y(index);
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62 | y(length(y)+1)=ymax;
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63 | nx=length(x); %number of grid points in x
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64 | ny=length(y); % number of grid points in y
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65 | B=(reshape(vec_A,nx,ny))'; %vec_A reshaped as a rectangular matrix
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66 | [X,Y]=meshgrid(x,y);% positions X and Y also reshaped as matrix
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67 |
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68 | %linear interpolation to improve the image resolution and/or adjust
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69 | %to prescribed positions
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70 | test_interp=1;
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71 | if exist('rgx_in','var') & ~isempty (rgx_in) & isnumeric(rgx_in) & length(rgx_in)==2% positions imposed from input
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72 | rangx=rgx_in; % first and last positions
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73 | rangy=rgy_in;
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74 | npxy=npxy_in;
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75 | else
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76 | rangx=[vec_X(1) vec_X(nx)];% first and last position found for x
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77 | % rangy=[ymin ymax];
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78 | rangy=[max(ymax,ymin) min(ymax,ymin)];
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79 | if max(nx,ny) <= 64 & isequal(npxy_in,'np>256')
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80 | npxy=[8*ny 8*nx];% increase the resolution 8 times
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81 | elseif max(nx,ny) <= 128 & isequal(npxy_in,'np>256')
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82 | npxy=[4*ny 4*nx];% increase the resolution 4 times
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83 | elseif max(nx,ny) <= 256 & isequal(npxy_in,'np>256')
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84 | npxy=[2*ny 2*nx];% increase the resolution 2 times
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85 | else
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86 | npxy=[ny nx];
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87 | test_interp=0; % no interpolation done
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88 | end
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89 | end
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90 | if test_interp==1%if we interpolate
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91 | xi=[rangx(1):(rangx(2)-rangx(1))/(npxy(2)-1):rangx(2)];
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92 | yi=[rangy(1):(rangy(2)-rangy(1))/(npxy(1)-1):rangy(2)];
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93 | [XI,YI]=meshgrid(xi,yi);
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94 | A = interp2(X,Y,B,XI,YI);
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95 | else %no interpolation for a resolution higher than 256
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96 | A=B;
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97 | XI=X;
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98 | YI=Y;
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99 | end
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100 | end
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