% REGULARIZE_3D_FIELD -  remove rigid motion from the reconstructed DVF 
%
%   shift_3D_total= regularize_3D_field(shift_3D_total )
%
% Inputs:
%    **shift_3D_total    reconstructed DVF
% Outputs: 
%    ++shift_3D_total    optimized DVF
%

%*-----------------------------------------------------------------------*
%|                                                                       |
%|  Except where otherwise noted, this work is licensed under a          |
%|  Creative Commons Attribution-NonCommercial-ShareAlike 4.0            |
%|  International (CC BY-NC-SA 4.0) license.                             |
%|                                                                       |
%|  Copyright (c) 2017 by Paul Scherrer Institute (http://www.psi.ch)    |
%|                                                                       |
%|       Author: CXS group, PSI                                          |
%*-----------------------------------------------------------------------*
% You may use this code with the following provisions:
%
% If the code is fully or partially redistributed, or rewritten in another
%   computing language this notice should be included in the redistribution.
%
% If this code, or subfunctions or parts of it, is used for research in a 
%   publication or if it is fully or partially rewritten for another 
%   computing language the authors and institution should be acknowledged 
%   in written form in the publication: “Data processing was carried out 
%   using the “cSAXS matlab package” developed by the CXS group,
%   Paul Scherrer Institut, Switzerland.” 
%   Variations on the latter text can be incorporated upon discussion with 
%   the CXS group if needed to more specifically reflect the use of the package 
%   for the published work.
%
% A publication that focuses on describing features, or parameters, that
%    are already existing in the code should be first discussed with the
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%   
% This code and subroutines are part of a continuous development, they 
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%    of PSI or the authors. It is the user responsibility to ensure its 
%    proper use and the correctness of the results.

function shift_3D_total= regularize_3D_field(shift_3D_total )
    Nblocks = length(shift_3D_total);
    for kk = 1:3
        % remove additional degrees of freedome 
        shift_3D_avg = 0;
        for ll = 1:Nblocks
            shift_3D_avg =  shift_3D_avg+ shift_3D_total{ll}{kk};
        end
        for ll = 1:Nblocks
           shift_3D_total{ll}{kk} = shift_3D_total{ll}{kk} - shift_3D_avg/Nblocks;
        end
    end
end