Meshing the point cloud

Select the point cloud and launch the 3D Mesh command.

Choose the 2 steps meshing strategy with an average distance of 20 mm. A default value of approximately 60 mm for hole detection is proposed.

Hit OK to create a rough mesh which contains the right topology and continue with the second step of the process which will refine the mesh.

In this refine step, select the following parameters:

• Select the Refining method as Refine Mesh from Cloud Interpolation

• Select the Mesh generation method as Refine with deviation error

• Default parameters for Deviation error, Maximum number of triangles and Minimum triangle size are calculated based on the rough mesh. These apply well here so no need to modify them.

• Check the Distance parameter and keep the default value so that sparse point do not affect the results

• Uncheck the options to apply a local reorganization

• Uncheck the options to filter based on the angle on scanning direction

• Finally, choose the option to refine the free border

Step 1 meshing to get a smoothed and accurate mesh from the point cloud

Step 2 meshing to get a smoothed and accurate mesh from the point cloud

From this mesh, a lot of geometric data can be extracted for defining a precise alignment.

Extracting the X axis

The X axis that we want to define is facing laterally to the blade.

Launch the Region Grow Plane tool and pick a point on the side of the wheel (the one which is less damaged!).

As we need only the plane information, you can leave unchecked 'Extracted Points' and 'Label' in order to keep only the 'Plane' object (the center point and the normal direction must be unlocked).

Plane extracted on the side of the wheel

Extracting the rotation axis

The rotation axis will be extracted on the curved circular area that we can see on the mesh, at the end of this plane.

To extract the circle, we will first extract the feature line:

1. Select the mesh and launch the Single Breaking Line command

2. Choose the option Only concave or only convex

3. Pick 2 points at the begin and end of the curved area as shown below with the 2 red balls

Extraction of the feature line

A polyline is created between these 2 red balls that follow the curved area of the mesh, i.e. the circle that we are looking for.

We will now create the axis that we are looking for by best fitting a circle on this polyline:

1. Select the polyline and launch the Best Circle command

2. Force the normal to be perpendicular to the previously measured plane:

   1. Lock the normal by clicking on the corresponding lock icon

   2. Select the normal with the option Direction of a component

   3. Pick the plane previously created

3. Keep only the circle as outputs

4. Hit OK

The circle best fitting the extracted feature line and aligned with the side plane

Calculate the middle plane

The middle plane that we are looking for is in the middle of the wheel and parallel to the side plane: its mathematical definition is the best symmetry plane that is parallel to the side plane.

In order to calculate a symmetric plane, an initial one must be created. This initial plane should be parallel to the side plane and close to the middle.

The following process is therefore required:

1. Duplicate the side plane with a Copy and Paste operation and hide the initial side plane.

2. Edit the newly created plane to approximate the middle plane

   1. Select the plane and launch Edit Plane or double click or use the contextual menu (right click) on the duplicated plane

   2. Drag the plane using preferably the blue arrow of the manipulator so that it is close to the expected result

   3. Hit OK

3. Calculate the best symmetry plane

   1. Select the approximated plane and the mesh

   2. Launch the Best Symmetry Plane command

   3. Define constraints and choose the option to Disable rotations (Only parallel plane)
      

   4. Hit OK

Translating the plane to an approximate position

Best symmetric plane calculated (in blue) from the approximated one (in red)

Computing the origin

The origin of the alignment that we are looking for is actually the center of the circle previously calculated projected onto the symmetry plane.

The steps to create the origin are the following ones:

1. Create the point at the middle of the circle using the command Point and the option Middle / Center or use other option to select the existing center if displayed by default.

2. Select the point that was just created and the Symmetry plane and launch the Projection command

3. Choose the Shortest distance option and hit OK, Exit

You can rename the projected point to Origin.

Projected point on the symmetry plane

Extracting the Y axis in front of the blade

The Y axis that we are looking for is facing in front of the blade.

The procedure to create it is as follow:

1. Launch the Region Grow Plane command

2. Hit 2 points (or more if needed) in front of the blade of both sides and validate with OK, Exit (if necessary adjust the extraction tolerance to 5or 10 mm)

Plane extracted in front of the blade

Applying the alignment onto the mesh

Every component previously created now allow to apply an alignment onto our data.

Select all the data and launch the Geometric Registration command:

1. The source point of the Origin will be the point named Origin

2. The main axis is X and is defined on the side plane

3. The second axis is Y and is defined as the front plane

4. Hit OK

The data is now aligned with X, Y and Z and the origin of the coordinate system is on the revolution axis of the wheel