Brandon Ruffin (bruffin776)

6 answers · asked · Lesson: Rigging the Wing II · Course: Short Film Character Production

When deciding how a rig should be created, when do you choose to use IK bones and MCH bones together like this?

I'm trying to understand the use case of IK and MCH bones.

Am I correct in thinking that the IK bones are for a base movement and the MCH bones more for specific movements? Fleshed out details of movement?

  • IK bone is the controller bone. the MCH are the mechanism bones that are used for calculating the inverse kinetics. More specific movements would be done through FK or forward kinetic control bones.

    • crew

      Dwayne offers good insight. I don't think my terminology is bullet-proof but I'll try to clarify: IK is the constraint type rather than a bone type, technically speaking. IK constraints and MCH bones are both serving as mechanisms of the rig. They both ultimately affect how the DEF (deformation) bones move the model, where CTRL (control) bones are the interface for the animator to move the rig (with its mechanisms).

      So the heirarchy is essentially this: DEF bones <-- MCH bones/constraints <-- CTRL bones

      Hopefully that helps clarify. waylow is the real rigging master.

    • Hi Kent! Thanks for the clarification.

      Yeah I'm not familiar with the DEF, MCH, and CTRL bone terminology when it comes to rigging, so I found myself lost in understanding the use case of each in the process. First time I'm delving so deep in the process.

      It seems to me that there's 3 main steps here, IK/MCH setups, and then there's figuring out the FK setups for the more specific movements needed, and then how the CTRL bones control the rig. In a nutshell. All to the DEF bones of course.

      This helps a lot you two, thank you for the help!

  • Hi Dwayne! Thanks for getting  back so soon, and apologies on the late reply.

    Oh I think I see what you mean. The MCH bones are, in another way, touching up on how the IK works, because it's very open ended by nature.

    And then FK for anything else that you may need. I think I'm understanding that correctly.

  • crew

    Hi Brandon,

    IK and FK are just names given to a specific type of control bone.

    Hopefully this video will help clarify things.

    Make sure you check out the rest of the course too.