Hi I was very exited of Bret Bays tutorial for IK/FK arm switch and I was wondering if it possible to use the same technique for a leg. I tried it and it works… kind of. When not keyframed the leg works just fine, but when I make keyframe to test it my knee brakes. After the key undo doesn’t work and I need to re-open the scene. Any idea why this is happening? May be if I turn knee pole this problem will disappear, but then it comes another problem: when switching between IK and FK the leg moves slightly…
I think I’m very close to solve it but I’m missing something. Also if I want the leg to be with no flip knee, I don’t know what to do…
Compared to Bret, I can only give a little advice here, as this was and is his main field. :o)
In the tutorial 3B after 04:00 he advices to check on the “Ik Tag from [Thigh_Con+ in your example] >>Attribute Manager>Advanced>Keep Goal”.
The foot should be handled as the Hand he takes in the “part 1 A/B” of this series. You use IK for a single Joint in the foot area, based on Bret’s suggestion, I guess. All I can see that it makes it more complex. Bret had the Hand added in Part 1A/B to the Blend [result] joint hierarchy. As it is now, if I move the foot-controller [while in IK] down, it affects the foot, but moving up will not restore it, until I go from IK to FK and back to Ik.
I would suggest that [on the Null-Object chain, which you have added under the Foot_CON+] to have as well a Keyframe-Selection only for the Rotations, as the Null hierarchy works here as a Joint-hierarchy from my perspective.
Yes, I found that the Auto pole set to 180º works better, perhaps even set to Y+.
Besides that - the priorities of all Tags are “Expression 0”, which you might check, as some are switched off and on independently based on IK/FK.
XPresso should be sorted in X-Manager.
Since the Foot and its [more or less] complex rotation, which Bret has discussed in detail, it is more a subject to IK, so far I can see it.
I hope that the little check box “Keep Goal” was the missing part. Fingers crossed.
I will check all your suggestions. About the foot - I used IK, so I can make foot_roll, foot wiggle, ball roll, rock out and in etc.
About the “Keep Goal” i tried with it and some weird thing happened, and in some point I turned off - can’t remember the reason…
I will bang my head a little more on this and keep you informed with the result.
Crossing the fingers it was the little check box. Anyway, I stick with the idea to follow Bret’s input to add the hand—respectively the foot—on the resulting joints, and handle it from there.
An old suggestion is, if one encounters a problem, then go back to the state where it works and start over, while controlling the steps based on the previous experience. In other words, if the leg by itself is stable and you can keyframe and switch, etc, it, then add more.
I think I found the problem - its not keep goal, I think is because there is a slide mismatch of the joint axis, IK goal axis and FK controler axis. Probably I should start it from earlier point… even before setting the FK controllers.
I’m not sure what exactly do you mean by: “I stick with the idea to follow Bret’s input to add the hand—respectively the foot—on the resulting joints, and handle it from there.” I need the order of controllers to be like this because of the upcoming creation of Foot roll.
In part 1 A/B Bret adds a hand on the arm, but he does it after IK and FK are blended. So the IK and FK switch is done and result in the Joint-Hierarchy. On this one he added then the hand.
I’m not clear how far it is a good idea to get a leg and an reverse foot in a kind off parallel set up, as an IK plus an FK mix and those long chains. I really don’t know how that will work during production, as I never have used it. I know that production requirements are “the easiest to use rig” is, but on the end it should be stable, right? Hence my suggestion to solve the leg, and when you get this stable add to the resulting joints the next step. Again, it is all in chapter one [A and B] of this three chapter, five part series. So why would it be a different suggestion for an even more complex chain…
My main concern would be that you can rotate Joints. In FK along all three axis if you like, which is not additive to the Pole object of the IK chain, which is needed to have the IK joints follow while inactive, to be in place when IK is taking over again. Like the lower arm rotates without moving the upper arm, etc. I have seen people suggesting it, and perhaps if one is careful – it works, but my concern is that during production a little un-intentional rotation happens, and before it is noted, things go down.
P.S.: When you check the rig, have an eye on Constrain-Loops. I haven’t found it yet, but have a look to this one minute clip of the effect. With one keyframe for the Foot-CON+ there should be no movement at all. Something is feeding information from something else and then back to it, like a feedback loop from a microphone. Perhaps you find it. Hence my suggestion, keep it separate and simple when you start over.
If only at one time a keyframe exist, as animation is the change between two states, a single keyframe can’t produce change. Hence my idea of a loop
I think I got to the loop that you meant. Now the IK Fk switch works perfect, when you don’t keyframe it. But when you add keyframe the joints disappear. I’m not sure which constrain should be first, second etc.
I’m also not sure how to keep it separate and simple - I would loose the Footroll…
I think now it’s a matter of order to fix it, because if you switch to Fk -> move the leg -> switch to IK -> again to FK nothing moves. :D
I think Chris Schmidt was able to do the same setup I found it here: https://vimeo.com/20455950
In minute 4:00 he talks about priority issues, but he was able to solve them somehow! :D
It is a little bit late here 2:00am, so I might allow myself to look into that in the morning, with fresh eyes. ;o)
I’m certainly willing to explore this, but let me ask you: what is it that makes you want to set up a lot of constrains and objects, to just avoid the IK/FK slider? What do you miss for your project
To get more about it, I have set up a file, very simplified and pretty much with some needs to make it more useable. However, this is all I need to get your input what makes you not like it. The Reset FK option sets the joints to the IK solution, and the PSR Constrains move the Goals to the needed position of the FK, as long as they are working. Simple XPresso here as well.
Again, even with all the set up in the files so far seen here as C4D file or video link (as Chris knows his stuff, he mentioned where this weekend project was at that time.), I haven’t seen something that works nor even close something that sets the Pole Objects where they need to be, once we move the joints not only 2D, which my arms and legs do all the time. This Pole object needs to be included to set things in sync. Other wise joints are not in the same position, as it is typical to follow in IK the Pole based “plane”.OR we just have two independent Joint-hierarchies, blended ...
(BTW, with simpler [you asked] I meant not less objects/joints, I meant to have the leg in IK/FK, and what ever moves the joints as an result, then—after that—is added to the resulting joint hierarchy, and not from the start into the mix. Again, as Bret has shown it in the Blend example. First solve the leg, then add the foot. Not all at once.
Let me know what you think about this little sketch.
I checked the file v3 carefully, and typically after a minute of key-framing it, I can break it.
Part of the reason why I do not enjoy long Joint Chains with Multiple IK set ups, each influencing the next is certainly given in the fact that I think that the “threshold” for the solving is always a variable.
Hence my idea to have for IK/Fk switches the main Joint chain solved and perhaps turned into Animation clips based on pure FK PSR values. If you take a look to the “Advanced Tab”, the iterations are set to 9999, just in case, as the IK is searching for a best solution, often it might take only a couple of dozens, but the threshold is there and normally one will not notice it, but in “feedback” systems like this, you take values from a to b, and after the switch from b to a, etc. This can easily add to noticeable changes. That’s the point where I can’t say how to avoid this. Hence my ideas above.
As I mentioned, Bret might have some advanced ideas and I’m not a professional rigger.
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I understand that you like to have an IK rig with a reverse foot solution. You also want to use an FK when you need it and the change should be invisible. As you mentioned, the “Blend” solution is here certainly preferable.
A minor idea would be to work always in IK, but have a Parent joint on top of it, and with that rotate the whole IK without changing it, just an idea/brainstorming.
I personally would prefer a Animation Clip solution, based on the results of both, but stored as the “Blend-Joints” and key-framed as such.
Thank you for the feedback Dr. Sassi - you are awesome!
The rig is personal project, I just wanted to do it.
You are right that this is getting way to complicated and even if I manage to solve the issues so far, probably it will break easily…
can you give me a little more info about the animation clip solution? Do you mean the solution with the pose mixer a.k.a. the new pose morph tag?
The animation clip workflow is perhaps very different of what an working IK/FK solution would do. Working with Animations Clips is like filming an actor and editing the clips in a time timeline.
Please have a look at the introduction to my series (which is not about Character Animation, but uses its tools heavily).
Animation clips take a complete hierarchy, and anything with the same hierarchy can be mixed then.
The advantage is here, that character expressions and motions can be blended, mixed, looped and manipulated in many ways. It takes some work on the start, but after the recording you can fine-tune the timing and so much more.
Practically, Perhaps have a FK rig constrained to an IK rig, and use the FK rig to “bake” these animation clips. So many options! :o)
It is a question of personal preferences if that fits or perhaps not at all to your style of creating.
