Landmark Registration in IBIS

We are using in IBIS LandmarkRegistrationObject for registering two images by a least square fit of two sets of user defined points, functionality provided by vtkLandmarkTransform and LandmarkRegistrationObject IBIS plugin.
The first set of points, called source points, is usually picked with mouse on an image in the scene ( e.g. MRI of patient’s head), the second, called target points, is picked with a tracked pointer in real world (e.g. patient’s head).
Points are represented by spheres in 3D view and by circles with cross hair in 2D views.

To create LandmarkRegistrationObject select
File → New Object → LandmarkRegistrationObject.

In order to pick, select, move points use SHIFT+mouse button.

Shift + left button click – select or add point
Shift + left button hold and drag – move point
Shift + right button click – select and remove point

Once the first set of points is picked with mouse, they will show on the list of LandmarkRegistrationObject settings dialog in the left side panel.

In order to assign corresponding points in world select first point on the list, pick point with pointer and click on Capture button. The point will show in 3D view and the next point on the list will be automatically selected. Fiducial Registration Error (FRE) will be displayed next to the point label, computed RMS will show above the list.
When picking is done, click on Register button. You may view the resulting transform going to Transform tab of LandmarkRegistrationObject settings dialog.

You may import, clicking on Import button, predefined points stored in MNI tag file. You may predefine only source points or both source and target.

Clicking on Details will show you a dialog with points coordinates, FRE and cumulative RMS for each pair of points. You may set the 3D view tag (spher) size of points.

In order to apply the computed transform go to the object list in left side panel and drag all the objects you want to register onto “Landmark Registration”.