Planning and Blocking
Taking a step further from the body mechanics task and involving a different level of intricacy involving Ik and FK switching allows the rig to perform actions more fluidly. Due to my lack of physical abilities, I used reference footage of an athlete jumping over a box as provided in class and wanted to try and match the smoothness and skill behind the motions performed.
Starting with the initial blocking, I used the reference to match the positions and speed side by side. As stated by Kenny Roy, “blocking is the most efficient stage ” to time and retime your animation, as you have clear and understandable keyframes before elements such as offset and follow-through crowd the timeline (2014, p.182). In my approach to blocking, I tried to use the IK/ FK witch in the process to experiment and see how this would affect the splined version. This replicates bodily movements in real life.
First Spline Pass
After converting the stepped tangents into splined animation, While the timing and general posing were, for the most part, incorrect placement, there were multiple issues, with popping in the IK/ FK switch process and Collision with ground plane and feet. However, the arms, hands and feet were generally the right place but did not precisely match where they should have been to avoid the ‘popping’. Using Syncsketch, I highlighted the issues on the exact frames they occur to later export as a Maya grease pencil file to import directly into my scene file.
Solutions to IK/ Fk Switches
FK (Forward Kinematics) and IK (Inverse Kinematics) Serve different purposes when animating a fully rigged CG character. FK means the positions of the limbs work hierarchically, meaning the hands will be affected by arms, and the arm by the shoulder, for instance. IK works differently as the hand is the leader of the rigging hierarchy, and the arm adjusts itself to the position of the hand, which is very useful in creating the animation below. Kenny Roy underlines how in Maya, the IK and FK function works as two different arms, so when animating, it is crucial to consider that the IK and FK will be switching skeletons. This implies that the FK will be in the same position as last keyed, so making a seamless transition requires different methods to get the two to match in 3D space (2014).
As learned in class, the geometry of the arms can be copied to freeze the position of the arms in place for spatial reference when swapping to the other skeleton. As seen below, the bony rig has a straightforward application of this method, and once unparented and assigned an alternate material, it works similar to ‘onion skinning. Using this method, I improved the popping and created a smoother transition in and out of the jumping motion.
While this works, I thought it helpful to look into the IK/ Fk switch processes to gain a better understanding of its process. For example, Kenny Roy draws light onto is using an ‘IK’ weight which enables the transition between the two by positioning the IK skeleton the intended frame keying the FK in progressive order to interpolate (2014). Using the Euler Filter to fix any gimbal lock issues that cause the rig to move sporadically and out of control. I found this possible using ‘set driven keys’ to create a blend between the two different skeletons in the rigging process.
FK IK switching in Maya using Set Driven Key – YouTube
To keep the hands effectively pinned to the box, locators can be used which prevent unrealistic slippage.
Working on these issues, I managed to clean the respective IK and FK switch glitches as clean as I could possibly make them. Focusing on follow-through elements in the finger and head movements. While this version is not perfect, and due to my inexperience in IK/FK switching, there are still several points, especially in the elbows and knees, where the constraints do not always accurately follow the rig.
Final Version (Rendering)
References
Roy, K., 2014. How to cheat in Maya 2014. Abingdon: Focal Press, pp.104-105.