Matching Props: Text Documentation

 Matching Props



The first thing to do is to place both your character and props Animation BluePrint (ABP) into your scene. Place both at any location as long as both objects have the same location (figure 1)

Figure 1

Then find out the inverse scale of the avatar. To do this we need the import scale for our character go to your characters IKinema Rig and under ‘Mocap Source’ we have our import scale (Figure 2).

Figure 2

The formula for the inverse scale is:

1/import scale x conversion ratio


Conversion Ratio:

OptiTrack Motive: 100

XSens MVN: 100

Vicons Blade: 0.1

Once you have your inverse scale, apply it to the scale of your character ABP that is in the scene (figure 3)

Figure 3

Once done go back to your characters IKinema Rig Editor and create tasks for your characters hands (figure 4)

1: Select a bone in the hierarchy and right-click

2: Go Constraint

3: And Select ‘Hand Task’

Figure 4

When creating hand tasks we need to reduce the retargeting gain on the Upper Arms and Forearms. We also need to reduce degrees of freedom (DoF) for the forearm on the axis where it bends. A good default value for the retargeting gain is 0.5 and for the DoF it's 0.1. This is to prevent instability in the solver (figure 6).

Figure 6

Next, we need to zero out the hand's tasks offset so that they match perfectly in world space.

Switch to constraint mode (figure 7)

Figure 7

1: Select the hand tasks

2: Expand the ‘Task Offset’ drop down and Zero out the X,Y and Z location

3: And tick ‘Lock Offset’

Figure 8


Once the task offset has been applied, we're all done. Jump back to your UE viewport and 'Play' the stream. If the matching isn't perfect some additional tuning may be required. 


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