Rigging the Hand
It’s time to create the rig for Jim’s hand and fingers. The steps are shown in Figure 11.6 and the instructions follow.
1. Create the bones for a single finger and give them intuitive names such as D_finger_3.1 to describe the finger position and the articulation number.
2. Create a bone with its head and tail aligned to the beginning and end of the finger chain; this bone will control the whole finger. At the tip, extrude a new bone that will act as the IK target. Duplicate that target and move it up to be used as the pole for the finger IK. In Edit Mode, make the C_finger_3 bone a child of the hand, and the IK target and pole children of C_finger_3. Apply an IK constraint to the D_finger_3.3 bone and set H_finger_3_ik as the target and H_finger_3_pole as the pole target. Set the IK Chain Length to 3 so it goes up through the finger bones only. You can try the finger rig now and you only need to use the C_finger_3 bone to control it. Rotate it to rotate the finger, and scale it up and down to flex the finger.
3. Now that you have one finger set up, duplicate it (Edit Mode) and place copies of it in the rest of the fingers and make sure to align them properly. For the thumb, you may want to delete the first articulation and use only 2 bones; just keep in mind you’ll need to realign the C_finger_1 bone to deform the bones.
Tip
Aligning the fingers may be difficult because the pole sometimes is not aligned in a single axis. What you can do in those situations is to put the pole in place in Pose Mode until the finger bones are in line with the model. Once you’ve done that, just select the bones you adjusted in Pose Mode, go to the 3D View header, and inside the Pose menu, look for the Apply option and select Apply Pose as Rest Pose. Alternatively, press Ctrl + A in the 3D View and select the same option. This will transfer the current transforms of the bones in Pose Mode to Edit Mode.