NeuroMotive™ User’s Manual
LB-0336 Rev. 1.00
Page 28
7.
Proximity elimination
When a marker is first defined, its position in the tracking area is saved. In this step, the possible markers that
remain after all of the above filtering are evaluated for their proximity to the saved position. The marker that has the
closest position to the initial position is deemed to be the actual marker and the rest of the possible markers are
discarded. And if more than one marker meets this criteria then the marker closest to what NeuroMotive™ predicts
to be the next position (based on previous movements) is chosen as the correct marker. The position of this select
marker is then saved as the new position to compare against.
When using multiple tracking markers this procedure is slightly altered to take advantage of the fact that the
positions of the markers relative to one another (the tracking ‘shape’) should remain mostly unchanged. When
multiple markers are defined their positions relative to one another (their shape) are recorded along with their
absolute positions in the tracking area. When evaluating markers, all the sets of markers in proximity to the recorded
positions that meet the shape criteria are then reviewed and the closest set of markers with the correct shape is
selected. If more than one set meets this criteria then the set that most closely matches the prediction
NeuroMotive™ has made on what the new position should be (based upon past movement) is selected. The new
positions of the markers are then recorded to compare against. Additionally, this prediction allows NeuroMotive™
to address object occlusion while tracking. Although occlusion of a marker may result in the tracking shape being
pinched as NeuroMotive™ tries to predict the position of the occluded marker.
At this point it is also important to note how NeuroMotive™ determines an object’s position in relation to the
markers being used for tracking. First, an object’s position is determined by the number of defined markers. For a
single marker the object position is the position of that marker. For two markers the object position is based on the
marker that is not the head marker. For three markers the object position is the midpoint between the markers that
are not the head marker.