Future of forward/inverse kinematics?

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Old 04 April 2003   #16
I'd love to see it in Maya. I was lucky to get a demo of Mirai before the whole Nichimen/Wingededge/Izware whatever thing happened and loved it. I still peek at the site every once in a while wondering if Mirai will ever come back.
Old 04 April 2003   #17
It exists already.....

Hey ya'll.....Allow me to jump in.

The reason why I'm jumping into this thread is because here at cinegroupe we have developped a pretty user friendly FK/IK 1 frame switch at the click of a button(with the help of scripting of course) It is incredibly usefull and after seeing many FK/IK systems throughout the biz, I must say that ours is quite impressive. I like XSI for this reason. And it doesn't bug out either, you just have to know what's going on.

The whole mystery of IK-FK blending in is an interesting one and the whole ability to do so has come a long way for both Maya and XSI.

What jschleifer has been talking about Mirai having the ability of IK/FK but NOT having function curves sounds strikingly familiar to Character Studio's BiPed technology. This system has been availabe on the market for the past 5 years I believe and is nothing new to the digital artist. The great engineers designing this system make the user believe IK/FK is at their finger tips. It's just a question of changing your manip tool from rotate to translate, and then placing a key. However what's going on in the arithematic behind the scenes is quite different. BiPed and Mirai do not use rotation coordinates. When you are saving a key you are saving the position in space(translation) and NOT the degree of rotation. So in reality, you ONLY have ik.

What I'm trying to say is that Mirai doesn't realy have IK/FK, it just feels that way for the user. The reason there are keys and not function curves is because the poses are only recorded in translation.
" True is real..."


Character Animator
Old 04 April 2003   #18

so if you take an arm and frame 1 of your animation and have it pointing down, then go to frame 10 and have it pointing up, what type of interpolation do you get?

jason schleifer
Animator - http://jasonschleifer.com/
Co-Founder - http://www.nimblecollective.com
Old 04 April 2003   #19
theres a bit more to it than just how its mapped. personally im after a setup that doesnt require me concentrating on what happens underneath when i use a certain form of posing. the tools for posing are just as important. for example.. Ik scale ( doesnt scale bones ) for example lets you take a characters arm, and do something like reach for a certain point in space. you just pick a vertex and the joint will try to reach it regardless of axis. so you dont have to rotate viewport.. translate arm/rotate... then tumble viewport again. .etc. you just pick a vertex ( joint ) and where you want to go.
things like FK symmetry are also useful. if i use left click on rotate one bone rotates. if i middle click on rotate however, the bone that i specified as a mirror will rotate the same number of degrees as the linked arm. i know jason started this thread only on IK and stuff. but i want my video to cover a wider range of Character tools that i find to be useful.

( btw. i dont animate much. but from a test i just made. when i moved the arm up 10 frames later it looked like it was an FK move. would kinda make sense.. since when i decompose the channel into multiple curves i get FK rotations.

personally what I am after is something like this.

say i animate a characters leg inside the viewport. i use Ik or FK to pose it. i can then after placing a few keys turn on the curve for that joint and i will see a curve inside the viewport as i make it. i would then also be able to use spline like tools to edit the path of the spline. and do stuff like refine it.. delete points.. this would translate to Fcurves.. but in 3d form. much like trajectories.. but would happen more interactively.. and syncd with my skeleton. so if i delete a key in the animation editor.. i would see a vertex in the spline dissapear. stuff like that would be nice.

anyway still working on video got a bunch done already
itll cover stuff like morphs too. ( to illustrate a less supped up version of what was used on lotr

Old 04 April 2003   #20

here I found a tutorial from an animator, who developed a pose-to-pose-animation workflow.

http://www.keithlango.com --> Tutorial --> pose-to-pose

Check the comparsion-video on the bottom.
Also the Maya-to-Max renderkit (http://www.keithlango.com --> tools) is great.

This of course would still keep the IK/FK - switching-problem

Thanks to the tutorial autor !!!
Old 04 April 2003   #21
Did anyone look at the video?
Old 04 April 2003   #22
Yeah what you are talking about does sound very similar to Biped in character studio for 3dsmax. It has the locks for arms and feet, and if I remember corectly (im using maya now ) all you needed to do to go between Ik and Fk with the Character Studio is just start rotating joints to get some FK control.. or if you want.. just select the hand and drag it arround and there you get your IK.

I wonder if someone could actually do an in-depth comparison of Mirai's animation tools and the ones found in the Character Studio package.

Real interesting stuff.

Old 04 April 2003   #23
I personally also wish maya had something like this (or at least an option of some sort)....BUT I would still like to keep the graph editor. There is something about playing with curves that I feel is very important in animation. BUT the fk/ik thing is still gnarly when you have to change timing and whatnot....takes ALOT of organization and is very frustrating when a director wants the timing changed. I've seen a lot of videos using Mirai and I always loved the fact that they could do stuff like you explained in your first post Jason. Makes total sense to me. Could be very helpful and possibly push animation in another direction (ie while also making complicated animations a tad be easier to grasp) I'm all for it.

They should just merge Mirai and Maya is what I think.
::b.Schulz . CharActeR aNimatoR ::
Old 04 April 2003   #24
Originally posted by ambient-whisper

personally what I am after is something like this.

say i animate a characters leg inside the viewport. i use Ik or FK to pose it. i can then after placing a few keys turn on the curve for that joint and i will see a curve inside the viewport as i make it. i would then also be able to use spline like tools to edit the path of the spline. and do stuff like refine it.. delete points.. this would translate to Fcurves.. but in 3d form. much like trajectories.. but would happen more interactively.. and syncd with my skeleton. so if i delete a key in the animation editor.. i would see a vertex in the spline dissapear. stuff like that would be nice.


Yeah...I too have been telling co-workers this idea. It's like in Maya if you would create a motion trail from say your root joint so you can see your arcs/paths etc. in some kinda line form. BUT you can't modify it unless you modify your keys, only then will it update the curves. It would be awesome if you could have some sort of representation of your keys on that curve in the viewport and you could manipulate them to get the curves you want and your animation would update from changing those curves. It would be more like a more complicated graph editor only in the viewport in 3d. Glad to hear that I'm not the only person who's thought of something like this.
::b.Schulz . CharActeR aNimatoR ::
Old 04 April 2003   #25
Only thing about Biped, if I remember correctly sinse I haven't used it for about 4 years, is that it is very limited animation wise.

Sure it works great for humans, but last time I used it, anything beyond a Biped creature (ie: 4 arms, 3 legs, A monkey, dinosaur and so on), your pretty much screwed, because you can't just add joints and control features to it, so you give up the control for more user friendly animation, which is not really the future of animation I would hope. (I haven't used the latest CS studio so maybe they have improved it).
*Insert pretentious quote here*
Old 04 April 2003   #26
Just saw the video. Yeah it seems like mirai in a way of moving things. Very much like sculpting or stop motion animation. Seems like with that ghosting option you proly wouldn't necessarily NEED a graph editor. What did Sega use this for and what's it doing now, collecting dust??? Looks rad to me.
::b.Schulz . CharActeR aNimatoR ::
Old 04 April 2003   #27
The great thing about this idea (I don't know if character studio can do this), but you can lock down other parts of hte body besides feet and hands.. for example, an elbow. How many times have you wanted to have a character rest their elbow on a table & have to make a funky setup just to handle that case? Or what about knees? I know a certain character (Gollum! Gollum!) which would have been a lot easier to animate if I could lock the knees down instead of having to counter-animate & key frame by frame to get the knees to stay in one spot.

The nice thing about mirai's sytem (from what I've seen) is that you can lock ANY part of the body.. not just hands and feet, but fingers, toes, knees, elbows, torso, root, etc etc.

jason schleifer
Animator - http://jasonschleifer.com/
Co-Founder - http://www.nimblecollective.com
Old 04 April 2003   #28
The sega app will be release during summer. cant wait to see more of it. looks really neato :d

as for mirai. id actually like for the skeleton to be more customizable. for example. you can make it look however you want... customise it to your creature.. add as many bones as you want where you want. theres base quadraped/ ticks/human skeletons. but umm it would be nice if i could get below the skeleton level customizations down to the bone level. so i could see the full structure of the skeleton inside the geometry graph ( kinda like outliner+layer editor in one ) that way i could do some parenting tricks.. etc.

im not sure if bay had the beta for mirai. but maybe he could tell you if they were working on that particular area. im sure it could be done if they tried.

one neato thing in mirai is that the skeleton is actually geometry. so it treats joints like verticies, bones like edges.. etc.
this allows a bunch of neat things like growing selections .. magnet deforms of the skeleton .
Ik scale. so what ik scale does really is...since joints are verticies..it just scales the distance between points. and the bones solve themselves to reach. but they dont stretch. its nice. theres IK rotations too.. but those i have no idea how to use properly. maybe bay could fill you or us in sometime.

also since the skeletons are geometry... you can use the morph system on it. so you pose a skeleton.. save... you can then use the magnets to pose a selected area with a falloff..

btw. im not sure why everyone is saying you cant use the graph editor to edit curves.. you can.. but you have to decompose your pose to pose channel into multiple curves... so then you can finetune them inside the curve editor. ..then you can compose that into a mocap channel. resample curves to have an N number of keyframes.. etc.

the area where this fails in mirai, is that they didnt give good managing tools for working with complex skeletons that have a crazy amount of bones. if you use the script graph you could make it a lot easier on yourself since you can hide any parts you dont want and work on specific areas.. but for some reason or another.. it doesnt update properly inside the mixer. ( area with all the sliders ).


[edit number-2]
got a lot of the video done i think ill just finish it off by making a short pose to pose animation. ( but i promise itll suck...since im no animator :d )
Old 04 April 2003   #29
The Mirai workflow has some huge plusses. It's keyframe management always struck me as a bit anemic, though. But I did dig the whole stop-mo feel of it.

Back when Big Idea used to be an animation studio, I was heading up some character rigging R&D for a future film (which won't be made) and Michael Comet and I kinda figured a simpler arm IK/FK system that didn't require switching, but allowed the animator to be in both modes at once. (It was actually more Michael than me It ended up being tons easier to rig, too. It just took some re-programming of the brain to get out of the IK/FK switching conventional wisdom. The crux of it was to set up the control objects for the arms in FK like normal, and then just parent the IK hand control under the forearm control. If you wanted the hand to be in FK, just use the rotation channels. If you wanted IK, you could tranlsate the hand away from it's 0-0-0 default and the IK would kick in as well. Meanwhile you could still do FK by rotating any of the arm controls up the heirarchy (like the forearm or upper arm or shoulder controls). Since the IK Hand control was parented underneath, it went along for the ride. The only thing was your upper chain control curves would be somewhat seperated from the arm, but that's turned out to be a minor annoyance more than a major problem. To "reset" the hand back to it's FK default, just set it back to it's 0-0-0 for the translate channels and it will go back to it's default position. It's hard to explain in text, but it's really pretty butt-simple to set up and use. And best of all, it requires no switching keyframes to manage. I can do a short description/tutorial and throw it up on my website if folks are interested. It's not the end-all-be-all, but I've fund it to be easier than the conventional switching paradigm.

But it's nowhere near the kind of global solution Jason mentions where you can lock down different body parts for a given sequence of frames. Maybe some uber-nasty constraint management system could be written to achieve this in Maya, but it'd be super ugly under the hood I suppose. We used a constraint management script Mark Behm wrote when he was at Big Idea. For simple stuff it was pretty clever, but if your timings ever changed it was a bear to work with. And if you had a few grabs nested into other grabs, switching back and forth and back again... ugh!
Yeah, something like Mirai's lock down feature would be pretty cool stuff.

keith lango
animator, storyteller, teacher
Old 04 April 2003   #30
I was thinking of an animation which would make any normal maya animator gulp.. and thought that if we could come up with a system that could handle that, then hell.. we'd be on our way.

okay, you have two characters. One is on a moving platform, the other is standing below him. Character A (the one below) runs up to character B (who is throwing apples, pears, and bananas down at character A) and starts trying to jump up onto the platform. After getting pelted a few times in the head, he is able to manage grabbing onto the platform with one hand. Then he swings his other hand on, brings up his leg and using his leg as a brace (i.e. locking down the knee & lower leg), hauls himself up onto the platform. Then he grabs at Character B, grabbing him round the left arm & swinging him around. Character B grabs at Character A, grasping his head & throws him down to the platform (still moving, btw). Then he grabs Character A's foot with one hand & lower leg with his other hand & swings him around, tossing him off the platform down a rocky slope. Character A lands head first, then butt first, then head, then leg, then arm, then does a double-summersault, then lands face down.

okay, so that'd be tough in any package. .but imagine trying to do that while trying to manage all the hierarchy changes which need to take place & all the fk/ik switching.

A simpler animation but still difficult to do with Maya's current fk/ik system:

A guy is sitting at a desk. Frustrated, he puts his elbow on the table, his head in his hands, and slumps his back, pushing the rolley chair that he's in slightly away.

jason schleifer
Animator - http://jasonschleifer.com/
Co-Founder - http://www.nimblecollective.com
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