1. Character Rigging for Animation in Maya
Longwood University
Kayla Lehman
GAND 410 Spring 2017
Project Goals
References
Process
Outcomes
Description
Images
Step 1: Modelling
The first task was to create the 3D model. While I have modelled many objects and a few animals before, this was my first time modelling a human. I start every model with a cube. Next, I add more edge loops to add more faces to the cube and continue to extrude those faces and adjust them until I get the desired shape. While most of the model was made from one piece of geometry, I did make the feet, hands, and heads separately and attached them to the main mesh. I also did some sculpting on the face to give the character more unique features.
Overall, I am quite satisfied with the outcome of this project. While the rig I created was fairly basic, it does have some complex mechanics and can create a variety of motions and poses. The part of the project that I am proudest of is the IK/FK switch on the arms. This took me several tries and a good deal of troubleshooting to get working correctly, but I knew that this was used a lot professionally so I really wanted to get it right. The versatility of motion that it offers definitely makes it worth the extra effort. The part of the project that gave me the most trouble and I am still not completely satisfied with was painting weights. While after a lot of tweaking and redoing most of the joint influences look natural, there are still a couple of places, such as the hips, where the mesh deforms a little weirdly when you move it a certain way. As I continue forward in rigging, I hope to learn more about painting weights so I can do an even better job on future rigs. In the end, I learned a lot of valuable information during every step of this project that will be useful to me for the remainder of my time at Longwood and in my professional career.
The process of creating a 3D animated film or game has many different steps and each requires a different set of knowledge and skills. As an animation student focusing on 3D, I want to learn about every aspect of production. My project focused on learning more about rigging 3D characters, a subject touched on in my 3D classes but not explained in depth. The process of rigging is crucial to the 3D animation pipeline. Rigging involves creating a set of joints within a 3D character model and a set of controllers that animators can use to move and manipulate those joints. This process is a lot more technical than artistic, so many 3D artists are not as interested in this part of production. For this reason, I believe that rigging is a valuable skill to learn to make you more competitive and versatile in the job market. I believe that this project will help me develop new skills and build my professional portfolio.
Step 2: Joint Hierarchy
Once the character model was completed, I was able to start the rig. Character rigging starts with creating a skeleton inside the character. First I had to determine what joints to include, since rigs do not contain every joint in the human body, and also how to connect them to each other to achieve the best movement. My final bone structure includes 57 joints, 5 for each leg, 7 for the spine and neck, and 19 in each arm, with 15 being finger controls. The joints are connected together in a hierarchy centralized at the pelvis so that they all follow each other logically as the rig is moved.
Step 3: Controls
The next step of rigging is creating controllers for the joints so they can be moved for animation. One of the biggest things I learned about in this section was the difference between IK and FK controls and how to use both in one model. When using forward kinematics, or FK, the motion is directed via rotation from the top down, for instance in the arm from the shoulder to the elbow. The rotation of the shoulder guides every joint after it. Conversely, when using inverse kinematics, or IK, motion is directed via translation from the bottom up. Using the arm example again, in IK the movement of the wrist guides the rest of the arm. This rig includes IK legs, an FK spine, and arms with an IK/FK switch, which was the most difficult control scheme to implement. In order to create the IK/FK arms, I needed to create three separate joint chains, an IK arm, and FK arm, and a “real arm.” First the real arm is constrained to follow both the IK and FK arms, and then a switch control is created that allows you to choose which of the other arms the real arm will follow. Finally, only the real arm is used in the main rig and the other two arms are hidden.
In order to complete this project, I had to do a lot of research and find several different guides, YouTube tutorials, and references. While I had some basic knowledge of what rigging was and what tools were involved, a full body model and rig definitely had many steps I had never done before. Starting with modelling, while I drew a lot of my own references, I used a template provided by Professor Donovan Douglas of Villa Maria College and a tutorial by Ryan Kittleson to assist me with modelling the character’s head. The majority of research I did concerned the rigging part of the project. Some of the references I used were provided by Professor Christensen, including a written tutorial for basic IK legs and an FK spine and neck setup. For additional leg reference and foot controls, I used a tutorial by Jason Baskin. For the IK/FK arm setup, I followed a video by CtrlAultDelTutorials.
Finally, a demo video by Robert Dyke gave me the idea to use set driven keys for the finger controls.
Step 4: Skinning and Painting weights
Once the rig is set up and able to be moved, it is time to combine it to the mesh so that the motion will influence the model, which is called skinning. However, the automatic joint influences are hardly ever correct, so you have to adjust the joint influence manually by painting weights. This tool projects a map of joint influence onto the model, with black showing that the selected joint has no influence and white showing that it has complete influence. Then, you are able to paint the influence onto the model yourself, getting rid of unwanted influence or increasing the influence of each joint on different parts of the body. Without this step, the joint influence works solely on proximity, which leads to issues such as the face and hair being pulled when the shoulder is moved. This step is crucial to refining a rig and making sure all of the motion works smoothly.
Acknowledgements
I would like to thank Professor Christensen for her guidance and assistance in completing this project, all of the tutorial and reference creators online that taught me so much about the rigging process, as well as the Cormier Honors College for printing our poster and holding this Poster Presentation Session.