Fiducial <--> Landmark - aren't they synonyms?

Reassigning to reporter.

I don't really find a proper reference, but very rough to have something to lean on:
http://en.wikipedia.org/wiki/Fiduciary_marker

"Fiducial is an object used in the field of view of an imaging system which appears in the image produced, for use as a point of reference or a measure."
For optical or EM tracking rather thank image based tracking this would be a sensor, which is used e.g. as patient reference.

"...In radiotherapy ... fiducial points are landmarks in the tumour to facilitate correct targets for treatment."

In http://en.wikipedia.org/wiki/Landmark_point
"...landmark is a point in a shape object in which correspondences between and within the populations of the object are preserved". And yes, "...In other disciplines, landmarks may be known as...ficucial markers".

I would propose to use fiducials when sensors are used for measurements and to use landmark when anatomical landmarks have to be pinpointed e.g. to create correspondence for registration.
Agree?

agree, jochen?

Wikipedia basically writes that they are synonyms. In the papers I read, they are used as synonyms too, but I read 'fiducials'/'fiducial markers' more frequently than 'landmarks'.

All in all, it's "geschmackssache" ;-) Do whatever you want or let the other IGT users vote for their favorite wording.

Well, we basically have the problem, that we have to differentiate between a filter that uses tools / sensors to compensate for patient etc. movement and another filter that uses corresponding positions to register two coordinate spaces.
I would like to call the first one a fiducial...filter and the second one a landmark...filter, because the term landmark is highly used by health professionals for coordinate- or image registration.

D'accord?

;) Ingmar

(In reply to comment #5)

..the term landmark is highly used by health
professionals for coordinate- or image registration.

And that's, in my opinion, the reason why "landmark" should not be used when we refer to navigation-related widgets (where tools/fiducials/NavigationDatas are essential). Widgets or filters which have no connection to tools/fiducials/NavigationDatas does not really fit in the scope of IGT?!

So I would vote for "fiducial" for classes using tools, which have to be inside IGT and for "landmark" for classes not using tools.

closing bug. No changes will be made.