Basic rigging question

Unleashed

Just learning rigging, after all these years, quick question: does the local rotation of a joint pivot matter for continuity? Like the direction of maya's pivot(green(y),red(x)blue(z)) should they be aligned from joint to joint or does that not matter?

Mark Dygert

Not only the orientation matters but the rotation order matters. Whatever your main rotation axis is for that joint you will want that to be last in your rotation order, to hopefully avoid problems with gimbal. If you use a quaternion based system you'll never have to worry about gimbal but since you're using Maya and quaternion rigs aren't all that prevalent (yet), get ready to wrestle with gimbal and rotation order.

Orientation and rotation order matter a lot, especially if you plan to use existing animations, or put your animations on an existing rig. The Unreal Marketplace requires all animation submissions to match the default unreal rig.

If your rig's main rotation axis is Y and you import animations from a rig that rotates on Z then everything goes crazy and bends the wrong way. There are ways to get motion mapped from different rigs but it's easier if you use

If everything is fresh and new, then it doesn't really matter as long as your rotation order is rock solid and combats gimbal as best as it can.

You will want the chains of each system (arms, legs, spine, neck ect...) to flow down a common axis and probably share a common rotation order. That way you can grab all of the joints/controllers and they all behave the same way when you rotate them all at the same time. If your fingers flowed down X but your middle fingers where flipped when you grab your finger joints and rotate on Y it would flip you off instead of making a fist, so all of those joints should probably match.

Unleashed

Thanks Mark, I guess it was too good to be true to have an erratic series of rotations. 

Regarding Unreal, while I'm only planning on using Unity for this personal project, what are Unreal's marketplace requirements for if your model is either something like fps arms(just the arms+hands in my case) or something that is a nonstandard human/completely different say an arachnid? My knowledge of UE4 is really thin, Im assuming by default rig its the one in https://docs.unrealengine.com/latest/INT/Engine/Content/Tools/MayaRiggingTool/RigTool_Rigging/ ?

Mark Dygert

Unleashed said:

... Im assuming by default rig its the one in https://docs.unrealengine.com/latest/INT/Engine/Content/Tools/MayaRiggingTool/RigTool_Rigging/ ?

Yep, that's the one. There are probably some sample files of built rigs or just the final skeleton and mesh, that would make good reference. I would copy the orientation and rotation order from the default, even for something like FPS hands.

Unleashed said:

... what are Unreal's marketplace requirements for if your model is either something like fps arms(just the arms+hands in my case) or something that is a nonstandard human/completely different say an arachnid? 

If the model could conceivably share animations with the default rig they require everything work. The joint placement doesn't have to be identical, the skeleton could be in the shape of a midget or a giant buffed out dude, but the rotation order and orientation should match so at least the rotations make sense, even if there are proportional differences that cause it to look weird. Its easier to clean that up, rather than animate from scratch.

If it's something like a tentacle monster or a griffin-snake-atar, then it doesn't have to match the default rig, using it as guide is probably a good idea tho... They do prefer that if it is a custom rig that it has some kind of base set of animations that could get a game going without requiring someone to rig it up and animate it.