Axis Registration

This command aligns the selected objects using 1, 2 or 3 pairs of points (called mobile and fixed points). This command will do:

• point alignment giving 1 pair of points. This is equivalent to a translation from the first point to the second point.

• linear alignment giving 2 pairs of points. This is equivalent to a translation + a rotation along an axis passing through the first point.

• planar alignment giving 3 pairs of points. This is equivalent to a translation + 2 rotations. When three point couples are entered, this registration method is also called Point-Line-Plane method.

Considering the 3 pairs of points are clicked, the software calculates the transformation that successfully does the following operations:

1. Translation from the mobile point n°1 to the fixed point n°1 (exactly). Note that you can click twice the same point to bypass the translation step and perform pure rotation(s).

2. Rotation around point n°1 to have mobile point n°2 on the same line as fixed points n°1 and 2 (exactly).

3. Rotation around the axis defined by the fixed points n°1 and 2 to have the mobile point n°3 in the plane defined by fixed points n°1, 2 and 3 (exactly).

This command may solve two types of problems:

• Making a coarse pre-positioning registration and then Best Fit Registration that is used to make the fine registration. In this case, the point couples (departure, arrival) are given roughly with a click on the shape because you do not need to be accurate.

• To make a geometrical based alignment. In this case, you must give points as accurately as possible because this method will not be completed afterwards by another "fine registration" method. Here, you will click particular points on the measurement object such as center of holes, corners, intersection of 3 planes, etc. and the corresponding target point, line and plane on the reference object (often an imported CAD object) or with explicit coordinates. Most often, to get this particular reference point, you will need to previously make a geometrical construction with commands computing best shapes or extracting shapes (in menu Construct or Old_Measure, Intersection, Projection, etc.). Then you will use the different options of Define points to extract the endpoint, middle, intersection, vertex, etc. It is also possible to enter an explicit coordinate such as 451.32, -523.45, 56.678 inside the XYZ field of Define points.

The most common way to use this command is to align two coordinate systems O-X-Y-Z and O'-X'-Y'-Z'. In this case the goal is to align the axis.