Nikholai - Week 6

The last week has been a productive and eye opening educational experience as I put my efforts into building the upper body sections of the player characters rig. The spine is by far the most complex part of the rig up to this point. Build up of a number of parts with the addition of the neck and head joints on top of the spine and the controls built for that. As an extra lay a ‘center of gravity’ is also found at the lower back of the model and this overrides all of the spine and head controls for one coherent animation solution.

The drive chain

The spine itself is a series of four joints that have been orientated correctly and placed accordingly within the upper body of the model. What does all the work with the spine however is the second set of joints, slightly bigger to allow for easier identification in the editor window. Is what acts as the ‘drive chain’ for the main spine of the player character. Contenting a number of constraints and an IK handle, the drive chain is created to handle the calculations of the main spine that it is parented too. From an animation point of view, this drive chain would be hidden. The controls that are constructed for the chest and hips allow the animator to move the rig as required with the hidden drive chain doing all the work. The method of building the spine is considered an intermediate technical level of rigging but is also said to be favoured over standard spine rigs due to it’s flexibility and robust results.

The controls for the spine are broken down into three main parts. The upper section of the spine is driven by the ‘chest control’. The box is a curve modelled to fit around the model and the rig to allow for clear identification and easy access for when animation. The same applies to the lower section or the ‘hip controls’. Both of these are parented accordingly and also offer a visual point of reference for the current rotation of the joints within the model. The head control is built in the same manner only this time being a different shape. The same rules apply to the manner in which it has been set up for the rig and the model. The last two controls are the center of gravity (C) and the neck controls which can be seen as the red triangle behind the rigs neck. These act as yet another point of control and allow for further, easier access to the controls and reduce confusion when animating.

Moving onto the neck and head section of the rig themselves things become a bit more simple in operation. The joints running through the head and neck are once again aligned to fit within the model for the skinning process later on in development. The joints will allow for believable movement of the head and neck as well as insuring correct deformation separate to the rest of the upper body section of the model. The final part of the rig that should be noted is the hips. To attach the spine to the legs they have been parented accordingly with the addition of a curve to mark the root point of the model. This is then parented to the hip controls to reduce any errors or confusion.

The spine twist

One of the more complex parts of the spine was using Maya’s ‘Hypershade’ window to sort out the twisting of the spine in a robust and believable way. The standard IK/FK systems did a good enough job but it quickly became clear that additional work would be required. Using locators parented to the drive chain of the spine I began the process of creating the ‘plus minus average’ system within the hypershade. This uses a series of nodes each with their own input and outputs and calculates the positional data required. These are then applied to the chest, hip and mid sections of the drive chain. The result of using the plus minus average node system is that as the spine twists, the system calculates the correct position to ensure believable twists. Further more, this system is a more robust and reliable method as compared to the standard spine rotation. The locators, which will be hidden at the end, allows for a clear visual indicator as to the angle at which the spine sections are facing.

The finished spine rig

At this point in time a lot of information has had to be processed by myself. I’ve thoroughly enjoyed the experience to this point of building the custom rig. Due to the skill level required for the tasks I have at times found myself a bit lost in terms of technical understanding and terminology. Regardless, I’ve pushed myself to ensure that I go out of my way to study further to gain a clear understanding of all these aspects. I expected this task to be a challenging one and up to this point it has proven to be so. That said I feel that I have put in more than what could be expected from me to ensure that I walk away from this having taking on all that I can and more. I continue to support this task with additional research and reading and I’m looking forward to moving forward once more. The following weeks goals will be to build the final section of the rig. The hands and arms as well as start to look at skinning ahead of getting the rig into Unity. Once done I can then spend time looking at the particle effects along with the animations that will be required for the prototype. It’s currently looking like I will be cutting it close but I’m still more than confident in the success of this task.