[IGSTK-Developers] Landmark3DRegistration

[David Gobbi]

Hi Andinet,

I looked at the Landmark3DRegistration registration code that
you just committed, and it looks like it requires the following
sequence of events:
1) ImageLandmark is added
2) TrackerLandmark is added
3) repeat 1 and 2 at least two more times
4) compute transform

This is good, the only thing that is missing is that at
step 4, there should be a check to make sure that the
resulting registration is accurate enough. 

A simple check is to make sure that the RMS of the registration
(the square root of the sum of the squares of distances between
the image and tracker landmarks after registration) is less than
some threshold e.g. 3 mm, that the application should be able to
specify via a Set method.

A succinct description of error calculation for landmark registration
is given in the following paper:
"Fiducial Point Placement and the Accuracy of Point-based, Rigid Body
Registration", West et al., Neurosurgery 48:810-817, 2001.
The methods described in the paper are a bit more advanced than what
we want to implement in this iteration, but the paper also provides a
very good description of all of the issues involved.
I'll see if I can dig up a copy.

 - David