Alingning a 3D point-cloud along its centerline

Hi,

I am trying to allign some large 3D point-clouds from scanned tunnels/pipes along their centerline. Based on different info I collected on this forum and eslewhere, I:

1 - calculate the direction/equation of the centerline

A=[x(:),y(:),z(:)]; % Point cloud 
m=mean(A,1).';
Atemp=A-m.'; 
% Singular value decomposition of matrix A, such that A = U*S*V'
[~,~,V]=svd(Atemp,0);
d=V(:,1);   % Direction vector of the centerline

2 - calculate the rotation matrix needed to align the direction vector with a reference vector

rot=vrrotvec(d,[0;0;1]); 
r=[rot(1),rot(2),rot(3)]; % Rotation vector
rot(4)=rot(4)*180/pi(); % Rotation in deg - for info
R=rotationVectorToMatrix(r);

A_rot=A*R;

While testing these lines on a cloud almost aligned, I end up with a cloud rotated in a random direction (A_rot), so I clearly missed out on something here.

Would anybody have an idea about what is wrong here?

Thanks in advance :)

[darova]

Can you be more specific? Can you attach the data

Please show the result picture you want to achieve