[czcezsqp] Curved manifold cross section

Embed a 2D manifold within a Euclidean 3D volumetric data set.  Mark the values of the 3D data onto the 2D manifold where it intersects.  If the 2D manifold is a plane, this would be cross section.

Let the 3D volumetric data be a 3D bar code with lots of error correction.  The marked 2D manifold samples only sections of the whole barcode, depending on the given shape of the manifold.  Recover the whole data using the forward error correction.

The intriguing 2D manifold is the skin surface of a human body, and tattoo marks the skin.  The exact shape of the manifold is a particular pose that the person has to remember and hit.  This provides a way of encrypting data in a way that can only be recovered if the person does that pose (and then is 3D scanned).  The password is not a word but a pose.  We need to be careful that the tattoo pattern does not give away too much information about the pose.  Randomly sample a point in the region in which the manifold intersects a voxel.