[V1,V2]=get_example_data

function [V1,V2]=get_example_data
% get_example_data is used to make some rigid and nonrigid transformed
% 3D MRI example data for the  registration examples.
%
% example,
% [V1,V2]=get_example_data;
%
% Function is written by D.Kroon University of Twente (October 2008)

% add all needed function paths
try
    functionname='register_images.m';
    functiondir=which(functionname);
    functiondir=functiondir(1:end-length(functionname));
    addpath([functiondir '/functions'])
    addpath([functiondir '/functions_affine'])
	addpath([functiondir '/functions_nonrigid'])
catch me
    disp(me.message);
end

load mri; D=squeeze(D); V2=single(D)./single(max(D(:))); clear D;
V2=imresize3d(V2,[],[128 128 64]);

Tx=imgaussian(rand(size(V2))*15-7.5,4,[20 20 20]);
Ty=imgaussian(rand(size(V2))*15-7.5,4,[20 20 20]);
Tz=imgaussian(rand(size(V2))*15-7.5,4,[20 20 20]);
V1= movepixels(V2,Tx,Ty,Tz);
V1=(V1<0.9).*V1;
t=clock; t=rand(1,round(t(6))+1); clear t;
par=rand(1,9)*14-7;
M=mat_tra([par(1) par(2) par(3)])*mat_siz([1+par(4)*0.01 1+par(5)*0.01 1+par(6)*0.01])*mat_rot([par(7) par(8) par(9)]); 
V1=affine_transform(single(V1),single(M));
V1=imresize3d(V1,[],[80 80 40]);

function M=mat_rot(r)
    r=r*(pi/180);
    Rx=[1 0 0 0;
        0 cos(r(1)) -sin(r(1)) 0;
        0 sin(r(1)) cos(r(1)) 0;
        0 0 0 1];

    Ry=[cos(r(2)) 0 sin(r(2)) 0;
        0 1 0 0;
        -sin(r(2)) 0 cos(r(2)) 0;
        0 0 0 1];

    Rz=[cos(r(3)) -sin(r(3)) 0 0;
        sin(r(3)) cos(r(3)) 0 0;
        0 0 1 0;
        0 0 0 1];
    M=Rx*Ry*Rz;

function M=mat_siz(s)
	M=[s(1) 0 0 0;
	   0 s(2) 0 0;
	   0 0 s(3) 0;
	   0 0 0 1];

function M=mat_tra(t)
	M=[1 0 0 t(1);
	   0 1 0 t(2);
	   0 0 1 t(3);
	   0 0 0 1];