Hey Wayne,
You mentioned there are two ways to solving the issue of the knee not pointing in the right direction (I can emphasize with that 😁) in rolling the bone to point the X-Axis in the right direction or using the pole angle in the constraint. I'm just wondering if there is a preferred or more correct method between the two of ways, and if there are potential issues, which can arise from either method. Or is it a riggers choice?
Rolling the bone sets the joint’s default orientation, making IK/FK and skinning predictable. Using the pole angle keeps the bone’s rest pose intact and lets you tweak dynamically but can cause flipping if misused.
Most riggers do a bit of both: small bone roll for a clean rest pose, then pole angle for fine control.
It's more of a preference thing. For example I prefer the bending axis to be x thus bone roll wouldn't work for me since this would make x axis point to the pole target. If you don't care or you prefer bend on z axis then you can use either method depending on which one is easiest for you. Just remember to be consistent.
Great question Sascha,
I'm pretty sure the answer is just preference.
The thing that you DON'T want though is for the bone to drastically jump when you switch from edit mode to pose mode.
I call this 'mode shifting' - which is not an official term. I don't think it has one, but I think it sounds cool.
Ideally you want it to stay exactly in the same spot but sometimes that isn't possible.
Small shift is fine, large shift is not.
As to why it points to the X axis - I'm not actually sure. Maybe that was just chosen arbitrarily by Ton 30 something years ago?
Logically it makes sense because it's the first axis.
But technically the Z axis makes more sense because when a bone is symmetrized, the Z axis is the horizontal mirror across the X (pose space).
Where as the X axis does not. (it mirrors on the z)