Digitizing Pointer Landmarks

Switch the system into ‘Live’ mode and ensure that the trial list has a subject ID (for example, ‘Pointer Trials’) for the session. Now select Hardware>Acquire Pointer from the menu at the top of the ODIN window. When selecting Hardware>Acquire Pointer for the first time in the session, the following pointer dialogue box will appear.

This box is deliberately large so that it can be read easily even if the user moves away from the screen to use the pointer. The dialogue box shows a list of all the defined Landmark points in alphabetical order. When the Landmark point is highlighted (as in the example of ‘Left ASIS’ above), the user must point and click at the required point with the Codamotion Landmark Pointer. If both the pointer and the markers defining the associated rigid body (cluster) are in view, the name will turn green and the menu will advance to the next Landmark point. If there is occlusion of one or more of the required markers or of the pointer itself, the name will turn red and an error message will inform the user which markers are not visible. The user can navigate up and down the list of pointer landmarks by pressing either the ‘Next’ or ‘Previous’ button at the bottom of the screen.

Re-digitizing

In the case where one cluster has moved, only the landmarks associated with this cluster need to be redefined. When selecting Hardware>Acquire Pointer for a second time (or more), a different window will appear (see below). This window allows the user to digitize only the landmark(s) associated with the cluster which has moved. Simply select the landmark(s) to redefine and click on “Re-digitize Pointer Session”. The initial large box will then reappear and show the list of the selected landmark points in alphabetic order.

The new pointer landmarks will only be applied on the recording of future trials and in the live mode. Old trials will keep the old pointer session data. ODIN automatically keeps track of the pointer session relevant to each recorded trial. If you want to re-digitize all the pointer landmarks (for example, for a new subject), then after having selected Hardware>Acquire Pointer, simply select “New Pointer Session”. The initial large box will show the complete list of landmarks in the alphabetic order. Note that ticking the complete list of landmarks and clicking on “Re-digitize Pointer Session” has the same effect as directly clicking on “New Pointer Session”.

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