The align commands are for making groups of control points co-linear or co-planar. The Align to Vector command aligns points along a 3D line in space, while the Align to Plane command aligns points to a specified plane.

Align to Vector differs from Smooth and Straighten in that the points selected do not have to be in the same row or column, or even in the same surface. You may select any control points to define the vector or plane, and then align any control points with that vector or plane; the control points need not lie in the same surface. You must also select all the control points to be aligned, patches may not be selected as they are in the Smooth and Straighten commands.

To use Align to Vector:

§   Select two control points with the shift key held down.

§   While still holding down the shift key, select one or more additional points.

§   Select the Align to Vector command.

The first two selected control points define the vector; all subsequently selected points are moved to the point on that vector closest to their original position:

§   Before aligning, endpoints with vector defined by two middle points

§   With shift key held down, select two middle points to define vector

§   With shift key held down, select two end points to be aligned

§   Select Align to Vector; end points are moved to closest corresponding points on the vector

This feature is very useful for ensuring co-linearity of control points either side of a bonded edge to ensure that the surface is slope continuous across that edge, or for creating a straight bow. Align to vector can also be used to ensure a smooth forefoot, going from the surface’s bottom edge to the bow; ensure that the corner control point and the two control points on each side, immediately adjacent to it, are co-linear:

§   Before alignment, discontinuity at forefoot

§   After alignment, smooth transition at forefoot

Align to Plane  works in a similar fashion to the Align to Vector command, except that the first three points selected define a plane in space that all subsequently selected points are moved on to.

Control points, other than those defining the plane, are moved to the closest position in the plane.

This means that a line between the new and old positions of the point would form a line that was normal to the plane.