Projecting a marker onto a line

There are many cases in which it is convenient to project a marker onto a line. One particularly useful scenario is to project a marker placed laterally on the shoulder at the level of the humeral head onto a line passing vertically through a marker on the acromium.

To create the landmark, switch to Model Builder mode and click on Add a New Landmark.

Create Marker_Projected:

Click Landmarks button

Click Add New Landmark button

Create Landmark: Marker_Projected

Landmark Name: Marker_Projected

   Define Orientation Using:
   Starting Point: Marker1
   Ending Point: Marker2
   Lateral Object: LEAVE BLANK
   Project From: Marker3

Do NOT Check: Offset by Percent (1.0 = 100%)

Check: Calibration Only Landmark

This will create a marker that lies along the vector from Marker 1 to Marker 2.