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Fiducial Registration Error

Last modified: June 7, 2006

The following applet demonstrates why Fiducial Registration Error (FRE) should not be reported as Target Registration Error (TRE), unless the fiducials are also the targets.

The Applet

  • Entering points - Clicking with left or right mouse buttons will add a new point.
  • Choosing target points - To mark/unmark a point as a target point click+CTRL on an existing point.
  • Registering - Click the button.
  • Adding noise - Click the button.
  • Add bias (FRE<TRE) - Adds a bias to all fiducial points.
  • Add bias (TRE<FRE) - Adds a certain bias to half of the fiducials and the negative of this bias to the other half.

Fiducial points are red and target points are green. To manipulate the point set just drag the coordinate axis, this will affect the set marked with Xs. Dragging the origin translates the points. Dragging/rotating the tips of the coordinate system will rotate the points.

Source Code

The source code for this applet and an application that allows you to save and load point sets is available here (java, zip file).