Future of forward/inverse kinematics?


consider this jedi -

i vaguely remember js mention of a situation wherein a character is resting on his elbows on a table and he pushes himself back on his wheeled-chair while the elbow is still in place.

so with pinning elbows makes that kind of move a lot easier. hope i made some sense.


yeah…am beginning to form a vague idea. Correct me if I am wrong here on the priniciple:

So you have a character resting it’s elbows on a table and the he pushes himself away. Now with a normal IK/FK system, you would have to key and counterkey the motion, to make sure the elbow stays where it is supposed to (i.e., on the same place on the table top). But with this “pinning” system, you get a natural lockdown of the elbow, i.e., you can animate everything else, but the elbow doesn’t move till it’s supposed to.

Thing is I am not really a full fledged animator, I am just in the process of teaching myself some animation. Thing is, I have faced a similar kind of a problem while making a character walk, i.e., the foot keeps slipping between two poses. I used to think that perhaps it was something which I was doing wrong…:wise:


bangOn! mate…you got that right.

and about your foot slipping between two poses…check if the keys in the graph are linear rather than in spline mode.


Thanks andy man.
Yup thats cleared up a whole lot of this discussion for me. I sure was :banghead: about this discussion.

About the keys, I suppose linear keys wold work, but, well, wouldn’t that make it really linear???:curious: I mean the animation will become pretty snappy won’t it?


or, instead of making those keys linear, just flatten the tangents for those 2 keys…where it lands and where it lifts off :slight_smile:
that way the foot will stay put between those 2 keys. :slight_smile:


thanks lord.

Will check it out…


i like the pinning concept, though functionally you can (and probably many of us have at some point) do the same thing in maya with animating contstraints, fk/ik switching, and all the rest of that complicatedness, and as somebody pointed out, a good TD could probably even make it work pretty easily for the animator in maya, i think that is more the question of a TD and animator or TD/animator hashing out the MEL, but its all time that has to go into a project, and time is money.

BUT do these tools give you animation curves to edit what is pinned on what frame, or what? i mean say you want to do some fairly radical retiming, changing how both arms and legs are pinned…


hi all…this is a test scene for the idea of making FK arms setup … with IK pose option …

i didnt test it in animation yet … but i notice small problem (not a problem but its the difference between the FK & IK inbetween ) even Animanum has this problem … but they fix it using extra cleanning proccess…

I didnt post this in new thread because i think people here are more intersted in testing new setups.

waiting the feed :slight_smile:


Love this thread.

I tried the SmartIK and it seems that you should add the twist to the CharSet and also lock the translation of the FK Controlers. What I don’t get is why the IK animation just gets “baked” into FK and when you go back to IK the animation is gone. This is a bit confusing but perhaps you can start a new thread and contivue discussion for your tool.


Hey all, Im new here and have some troubles to export an a fbx archive from maya to motion builder, it works with a low poli model but not with a hig poli one.
Anybody have someidea why !?? :cry:


I’m not talking about animation being easy, just about the tools in 3D animation being easy to use. I can draw a hell lot faster than I can pose in Maya, but of course, I mean sketch, not draw details. So if people could pose as easy as sketching that pose, in 3D, that would help 3D animation enormosly. BTW, I just bought a pen& tablet, and I’m posing with them in 3D, and it’s so much nicer than doing it with a mouse!!! More accurate and faster, feels a bit like drawing… :slight_smile:
I’m not complaining about Maya, and actually you can’t even compare Maya and Animanium. Animanium is just a tiny and very limited application, while Maya is one huge and extremely flexible 3D animation studio. But the WAY that Animanium handles character (well, body actually) animation is fantastic. Limited, yeap, but it allows you to pose faster than anything else I’ve tried. And I really tried a bunch. If you could blend the ease of use of Animanium and the flexibility of Maya…
Now, I believe that if you work pose-to-pose, the ease and speed of posing is vital (in other words - how much time does an action take you - any action, like rotating a joint (which includes selecting!!!) - 1 minute? 1 second? 0.00001 of a second? yeah, I’m exagerating, but my point is that if you can pose in “real time”, like you do when sketching - that’s almost “real time”, if you could pose as fast as thinking it - that’s what I’d call “real time” - , the computer wouldn’t be just a box. It would be an organic part of yourself, just like the pencil is.). Quality doesn’t necessarily have to be involved in this equation. Lots of good animators plan their work on paper (well, that paper can be a 2D application if you have a pen&tablet and feel very comfortable using them), because it’s so much more flexible and faster. Immediate feedback, right? That’s what we all want. I strongly believe that if you give animators a system that eases and speeds up their workflow, that will have an impact on quality as well - Richard Williams: “I actually think the video and computer have saved animation” - my comment: because of the power of feedback!
My way of working is entirely FK, although I might animate IK feet sometimes… but I’m not very comfortable with IK. My big problem is locking, of course - so I do it by hand, in FK, and ghosting helps a lot with that. It’s a trade - I’m trading the speed and locking possibilities of IK for the accuracy of FK. IK for me is like “taking the long shortcut”. I just can’t work with it. Well, that’s just me. I guess lots of people use IK to lock stuff, and otherwise use FK extensively… (so I’m not a fan of Animanium’s legendary IK engine, but of its rotating-through-translation approach, which is what I miss in Maya).
As you say, “GOOD QUALITY animation takes effort and hard work” - of course, but I’d rather spend my time planning and replanning and hyperplanning. The posing part should not be more complicated than sketching. Milt Kahl, take him for example (no quotation on Milt, but I’ll quote the same Richard Williams, from the “Animator’s survival kit”): “Milt often told me that by the time he’d plotted everything out this way [planning and replanning and hyperplanning - my note], he’d pretty much animated the scene - even including the lip sync”
Simplicity!!! Same good ol’ Richard says that animation is complicated enough as it is, why make it more complicated? I think we should be thinking more on body dynamics and arcs, and of course, on acting, rather than how to select, deselect, etc. Free your mind and simplify your life - that doesn’t mean you won’t work as much as you did before, or maybe even more ('cause if you’re excited…), it only means you’re going to be more efficient.


…other good stuff snipped…

Couldn’t have said it better myself dude. You bring up some great points, simplicity being one of the most important. I just switched over to Maya about 5 months ago, and I still haven’t gotten over how complicated they make things. I asked alot of Maya users how they select objects, and I get the “I select things in the outliner/hypergraph” answer alot. I also hear how they have a GUI to select their controls or whatever. I’d much rather select things in the viewport but this doesn’t really work in Maya cause of how it treats selections within hierarchies. If I select say…the pelvis node and the hand node, not only does the pelvis and hand turn white, but so does all the other controls/bones inbetween, so you don’t know exactly what things you have selected. Hence the need to have to use the outliner/hypergraph to select objects. It’s just minor things like this that are too complicated that shouldn’t be.

and M.E.L.
I’ve got a complaint about Maya. I’m coming from a MAX animation environment and I don’t know if you are familiar with it or not, but they don’t have pole vectors for leg/arm IK chains. MAX never gets that “flipping” that occurs in maya once the IK handle reaches that 180degree line. I’ve been told by my TD’s that you have to have those pole vector controls on your rigs in Maya. I couldn’t belive this at first but it does make sense seeing how every free rig I’ve downloaded of the net has these pole vector handles. I’ve learned to just deal with it. It’s just another thing that makes posing more “complicated” in Maya…Why don’t the knees just keep their orientation damnit!!! :slight_smile: I hope I don’t turn this into a MAX/Maya thing, I’m just trying to point out problems I see within animation environment in Maya that could possibly be improved. Anyways, if anyone has any ideas on how to get rid of those annoying pole vectors please let me know.

I’ve seen that list of new stuff they’re putting into Maya 7 and I noticed the inclusion of Motion Builder’s full body IK system. I know alot of Maya animators might not be familiar with what this is, but you are in for a real treat! I’ve used Motion Builder a little bit, and it has the ability to pin/lock any joint in place. MAX’s old Interactive IK has this same system. Imagine being able to lock, say…an elbow down while you move the pelvis instead of just locking the hand. You could also, for example, pin the head down and then move the pelvis and whole torso would move somewhat similar to a spline IK controller. It works with rotation too, not just translations. If you have a torso with 3 main controllers and the middle controller is all twisted too much, just lock down the other 2 controllers, then rotate that middle controller till the torso has a nice even curve to it. The other two controllers won’t go anywhere and will be locked in place. This allows you to not only pose characters even faster than before, it also allows you to go back and make tweaks to your animations even faster too. I’m just crossing my fingers hoping Alias doesn’t make this new IK more complicated.


but they don’t have pole vectors for leg/arm IK chains

That would be the bIped in max and not Traditional max bones which are subject to the same pole vertor issue as are thye maya and XSi bones…


I’ve never used Biped. Biped is Character Studio, where did I mention this in my post?

Create some bones for a leg in MAX and put an IK solver on it. Move the IK handle around in a circular motion around the root. Notice how the knee doesn’t flip. All MAX IK solver has is a twist value for the knee. Their “pole vector” always stay perpendicular to the IK handle.


Biped is Character Studio, where did I mention this in my post?

I never said u did, mate …

Create some bones for a leg in MAX and put an IK solver on it. Move the IK handle around in a circular motion around the root. Notice how the knee doesn’t flip. All MAX IK solver has is a twist value for the knee. Their “pole vector” always stay perpendicular to the IK handle.

my bad: it does exactly that…but …

Assuming u created the bones in the left viewport then if u move the ik handle around on the YZ plane then its all hunky dory… but if u were to move the ik handle on the XZ plane that no longer seems to be the case-we get the same familiar flipping

If u try the sc plane solver in maya u will get the same result as u do in max
( tho the twist and the pole vector do not work in that case- atleast I couldn’t get it to work ) maybe it has to do with the fact that the SCsolver tries to match the handle’s position as well as the orientation… something which the RPsolver does only for the position and not the orientaion … by virtue of which it gives more predictable results and is the prefered solver with the caveat that u have to use the twist attribute or the polevectors for joint flips.
But after the creation of the Rp solver if u put 90 as the value for the pole vector x and 90 as the value of the twist … and then manipulate the IK handle u get the same result as max even tho u use the RP solver…
As u said In max the polevector is perpendicular to the solver plane right from the start … in maya’s Rp solver it is on the same plane… its an additional step for u, but like many things in maya its exposed for us to manipulate

I hope I haven’t been confusing … now then … the implementation of motion builder’s Ik system would be a very wecome addition in maya’s arsenal.


No problem, I understand what you’re talking about.

I also remember seeing something in the list that said they’re going to implement a “Spring IK” controller. Said it was useful on stuff like insects legs. Not really sure what they mean but it sounds interesting.

I hope Maya also takes a look at Motion Builders viewport speed too, it’s rediculously fast. We were able to take our high-res cinematic model(40,000+ polys) and get ~80fps playback rate in MB. I’m lucky to get 30fps on our 5,500 realtime model in Maya.


Wow ! 80 fps on a film res character …

ps: u Might want to hand around to check the biped tweaks they have reportedly done in max 8 …if rumors are true then its has euler cntrls for roation in Biped ( yaaaaay finally function curves in Biped )
and wrist twist, upper arm twist etc…maybe as a competition to the upcommiong MB IK sys in Maya.

but what these upgrades do is bring my dream ik sys nearer to reality … no FK/ IK/ Skin bind joints crap and fumblimng around for keys when the director decides to change his mind and wants the character to do something totally diff…grrmaybe a shtgun would do


Looks like the ball that JS got rolling with this thread finally came tumbling out of Alias:


Not familiar with Motion Builder so I will ask something that will sound dumb… dumb or not I don’t care so I’ll ask anyway :smiley:

How good is the full body IK to the ik-fk blending stuff?

dumb mode off


OK… ·Dumb mode on·
I’m really are a new motion builder user, so I dont know ho is the better path. My experience is shortly and I find more intrested to use the skeleton in motion builder than maya because it let me see the animation on real time, but for know, I find a strange way to do the job. Is something like use the motion builder to create the movements on the skeleton and later export it like fbx to maya, so you have a skeleton with the the same name bones in each softwear, and then you can paste the motion builder animation in maya, with a good skining and a correct IK.
I know is very amateur… sorry… but for now is the better way that I find. If someone knows another more professional way just let me know !!

·Dumb mode off·