MATLAB rotation problem -

hey all, need rotated versions of 3d shepp logan phantom , it's corresponding rotation matrix. here's thing, use function called phantom3d create 3d slp, function allows euler angles specify rotation. example:

phi = 45; theta = 45; psi = 45;  %just matrix of inputs create shepp logan phantom e =[  1  .6900  .920  .810      0       0       0      0+phi      0+theta      0+psi     -.8  .6624  .874  .780      0  -.0184       0      0+phi      0+theta      0+psi     -.2  .1100  .310  .220    .22       0       0    -18+phi      0+theta     10+psi     -.2  .1600  .410  .280   -.22       0       0     18+phi      0+theta     10+psi      .1  .2100  .250  .410      0     .35    -.15      0+phi      0+theta      0+psi      .1  .0460  .046  .050      0      .1     .25      0+phi      0+theta      0+psi      .1  .0460  .046  .050      0     -.1     .25      0+phi      0+theta      0+psi      .1  .0460  .023  .050   -.08   -.605       0      0+phi      0+theta      0+psi      .1  .0230  .023  .020      0   -.606       0      0+phi      0+theta      0+psi      .1  .0230  .046  .020    .06   -.605       0      0+phi      0+theta      0+psi   ];  img = phantom3d(e, 50); 

now according literature can calculate rotation matrix using:

phi = ((phi + 180)/180).*pi; theta = (theta/180).*pi; psi = (psi/180).*pi;  cphi = cos(phi); sphi = sin(phi); ctheta = cos(theta); stheta = sin(theta); cpsi = cos(psi); spsi = sin(psi);  % euler rotation matrix alpha = [cpsi*cphi-ctheta*sphi*spsi   cpsi*sphi+ctheta*cphi*spsi  spsi*stheta;         -spsi*cphi-ctheta*sphi*cpsi  -spsi*sphi+ctheta*cphi*cpsi cpsi*stheta;         stheta*sphi   

however, if compare image create using phantom3d function applies rotation matrix on non-rotated image, don't rotate in same way. code view rotated versionof image is:

img = phantom3d(50); szout = size(img); cf = eye(4); cf(1:3, 4) = -szout/2; co = cf; %previously created alpha alpha(4,4) = 1; %cf & co used translations rmatrix = inv(cf) * alpha * co; [x, y, z]=ndgrid(single(1:szout(1)), single(1:szout(2)), single(1:szout(3))); xyz = [x(:) y(:) z(:) ones(numel(x),1)]*rmatrix(1:3,:)'; xyz = reshape(xyz,[szout 3]); img2 = interpn(single(img), xyz(:,:,:,1),xyz(:,:,:,2),xyz(:,:,:,3), 'cubic', 0); 

so need have img & img2 same, it's not. found case set psi, phi & theta 45 , add 180 phi when creating img2 gives same result, there relation can't seem find it.

anyone have ideas, suggestions, help?

thx lot

problem solved, apparently rotation on x axis different in function. when u calculate rotation matrix euler angles state be:

d = [cos(phi) sin(phi) 0 -sin(phi) cos(phi) 0 0 0 1];

c = [1 0 0 0 cos(theta) sin(theta) 0 -sin(theta) cos(theta)];

b = [cos(psi) sin(psi) 0 -sin(psi) cos(psi) 0 0 0 1];

r = b*c*d;

however in case c different, namely rotation on old y axis:

c = [cos(theta) 0 -sin(theta) 0 1 0 sin(theta) 0 cos(theta)];

if encounters similar problems, 1 should observe each rotation separately , study separate rotation matrices, euler , axis angles, because not every function uses same x,y,z axis or rotations in standard explained way.

anyway viewing