Build >> Register >> 2 Shells >> Initial

• Build  >> Register  >> 2 Shells  >> Initial command roughly registers one shell with another one using common geometric features on two shells. Common geometric features, also called corresponding points, are specified by a user. This command can be applied to the registration of the shells which have only point cloud data.

Step   

Execute Build  >> Register  >> 2 Shells  >> Initial command as follows:

1. Select Build  >> Register  >> 2 Shells  >> Initial from the menu or click the corresponding icon from the Build toolbar.

2. First, select a shell which will be moved, and then select a shell which will be fixed as the registration base. ( See Shell selection )

3. Select more than three pairs of corresponding feature points on two shells like shown below. Each pair of corresponding points is represented in small square in different color. ( See Selecting point )

The order of selection on two shells is not important. A user can select 3 or more points on one shell first and then select 3 or more points on another shell. Also a user can select one point on one shell and select corresponding point on another shell. And this applies for the remaining point pairs.

4. If a user clicks the right mouse button while executing this command, the following pop-up menu appears.

Select Pause to temporarily stop the current command and change to input ready state. Then, a user can use virtual trackball. A check mark appears in the front of Pause command in this state. Select Pause once more to resume the stopped command.

Select Undo Last to cancel the last point selection.

5. When more than three pairs of corresponding points are selected, Done command on the right mouse shortcut menu is enabled. Select it to complete this operation.

Result

• There are four grades for registration results as follows, and one of them is shown when this command finishes.

Excellent Good Not Bad Not Good

The results shown on the screen is not an absolute reflection but just a hint of the registration quality, for it is evaluated on the basis of model size. Thus, Excellent result may not be what a user really wants, while Not Good result may prove to be a relatively satisfactory outcome.

Note  

• rapidform takes into account the fact that pairs of corresponding points selected by a user are not accurate enough. The more accurate the corresponding points are, the better the result a user can get.

• For optimal performance and result, the number of selected pairs of corresponding points should be between 5 and 8. It not only spends too much time but also may bring bad results if you select too many pairs of points.