source: proiecte/pmake3d/make3d_original/Make3dSingleImageStanford_version0.1/third_party/zisserman/vgg_numerics/vgg_quat_rotation_matrix.m @ 37

function R = vgg_quat_rotation_matrix(q)
% vgg_quat_rotation_matrix Generates rotation matrix from quaternion
%               R = vgg_quat_rotation_matrix(q)

q00 = q(1)*q(1); 
q0x = q(1)*q(2); 
q0y = q(1)*q(3); 
q0z = q(1)*q(4);
qxx = q(2)*q(2);
qxy = q(2)*q(3);
qxz = q(2)*q(4);
qyy = q(3)*q(3); 
qyz = q(3)*q(4);
qzz = q(4)*q(4);

R = [ q00 + qxx - qyy - qzz       2*(qxy - q0z)           2*(qxz + q0y)   
          2*(qxy + q0z)       q00 - qxx + qyy - qzz       2*(qyz - q0x)
          2*(qxz - q0y)           2*(qyz + q0x)       q00 - qxx - qyy + qzz ];