Transform 3D point cloud

I have a point cloud and a rotation matrix like this:

rot=[ -0.48664090 0.36675647 0.79288739;

-0.67601788 -0.73296887 -0.075871207;

-0.55333579 0.57292831 -0.60462612 ]

How can I transform the point cloud using this rotation matrix? I cannot use this matrix with pctrasform and rigid3d.

[Matt J]

I cannot use this matrix with pctrasform and rigid3d.

Why not?

[Ernest Porqueras]

Error using rigid3d (line 139)

The rigid transformation matrix must only contain a rotation and a translation.

The final column must consist of zeros, except for a one in the last row.

[Ernest Porqueras]

I think this function only allows rotating along 1 axis.

Answer 1

[Matt J]

Funny. Well, you can always use affine3d,

rot=[ -0.48664090	0.36675647	0.79288739;
        -0.67601788	-0.73296887	-0.075871207;
        -0.55333579	0.57292831	-0.60462612 ];

T=eye(4); 
T(1:3,1:3)=rot;
tform=affine3d(T)

tform = 
  affine3d with properties:

                 T: [4×4 double]
    Dimensionality: 3

As a side note, your matrix is not a proper rotation, since its determinant is -1.

det(rot)

ans = -1.0000

Answer 2

[Bjorn Gustavsson]

If you have a 3-x-n array of point-coordinates you can rotate them in 2 ways, either rotate the points or the coordinate system.

For example like this:

r_rotated = rot*r_points;

HTH