 Welcome back to the FNA and today I want to talk about the most common pitfalls when you animate with IK arms. One of the many positive aspects of teaching a lot of classes that you get a very quick overview of many different skill sets of students and there are many different levels. But you can see a common through line of things that a lot of students get wrong or wrong as in just they don't have enough experience but something that happens a lot when they animate a certain way. And today I want to talk about IK arms. But before I do hi my name is JD if you're new to this channel and I do lectures like these I do animation analysis clips I do acting analysis clips I do rig reviews proc reviews and so on you know this is the pitch when I say what I do you can browse around the channel and if there's something that you like feel free to subscribe and hit that bell button so you don't miss any of my uploads that is the pitch you know it's YouTube there you go let's get back to IK and this is not an IK versus FK clip that's going to come later this is just generally if you do animate with IK arms this is what you're supposed to look out for let's go and I'm going to show this in two ways I did this a long time ago for my class this is a very old clip here but usually when you have a rig they move it around this is what happens they actually have Maya open you can see this here with eng you can grab the root and if you move the root around usually with IK arms this is what happens now there are different ways that you can get rid of that for all the rigs you just grab your IK arms parented on the root and at least when you move the root the arms will follow the problem of course is they go too far things can break they're all kinds of hacky ways where that solution is not going to work now it is rigs are fairly sophisticated there are lots of ways of IK FK matching and gimbal lock and all kinds of fixes but still even with all of that here's one of the first things that will stand out when you animate with an IK arm and you're not careful anytime you have an elbow that moves the wrist is not going to move either so if I go in here and I move that arm you can see here there's a pull vector there's a twist but if I do this if I twist that arm you can see that the wrist is not going to follow and this just feels very separate so it does if you draw a line here and everything you animate in this section here has zero influence on this sounds fairly simple but still you put your arms on the table which is why you would have for instance IK because you want to rest it you don't want to and you move the body around you don't want to move things from my frame but if you do this and you move the elbow around that wrist is going to feel very locked visually so every time you do something with the elbow you're gonna have to find a way to have that forearm influence that wrist so when I do this the forearm is going to take the wrist with it and depending on where the pressure is and everything you can have the pinpoint on the fingers you can do like that you can have all kinds of depending on what the lean is in the weight and everything but as you have anything resting on a hand and you move the elbow the wrist has to somewhat move with it obviously if it's like this and you move everything around then you have the hand that comes off the table there needs to be a certain pinpoint where things are not moving but make sure just that influence doesn't stop harshly when the forearm ends here and the wrist and the hand starts so again if you move the elbow the wrist here doesn't move not happy and if your wrist is not resting on a table and it's just floating like this in the air just make sure that if you do this you can see here that the wrist just follows with it of course he's happy about that so if you move the pull vector around make sure that you move the wrist as well but then again another pitfall you see with ik arms is that if you don't have any type of translate it's going to be such a strong pivot off of here because that is where the ik controller is resting as opposed to if you would just do this if i move my arm around like this and you can see this here i move it around like that you're going to have some sort of translate there's going to be some messiness in this again that messiness will depend on the style like how cartoon is going to be how realistic so that's always a bit of a thing that will influence how you animate but still if you move this around if i hold this like it just doesn't feel natural to have that right there so if you move this around there's going to be some translate so ik arms you move the elbow the wrist is going to stay put feels weird but if you move that wrist around with the forearm make sure that you don't keep that ik controller here stuck because then again it looks like that very clear pivot which again looks like a very clear ik arm so you're gonna have to have to move around that arm a little bit so it looks like it's more of an organic way of moving the arm another pitfall and this one is huge is that when you move an arm like this you can see not happy is that it's a very straight line you can see this here you move it from here to here and why is that well that's my dog he's very sad that i'm not taking care of him but didn't come in he just opens the door this is indy this is the culprit when looking to the camera here oh he's so cute but anyway this is not what the fna is about indy let's go let me close the totally lost my train of thought arms aka arms let's go so here's the thing you grab that arm right and let's say you have that arm here and then wherever i'm gonna set a key and bring that arm up here so when you play this you can see how unnatural this looks first of all you have a very straight line you can see here as you go up and you can also visualize this with a motion trail that is a straight path on top of that you can see that the wrist is not changing so you would have to move that wrist around so you have this pose from here all the way up potentially do something like this so as you move this you can see how the wrist is somewhat staying aligned with the forearm but again that straight path just doesn't look natural so just like i showed here this is not a good way to do this because again the path is too straight so one of the fixes like i showed that you have to align that wrist with the forearm this is still going to feel somewhat unnatural because it's just kind of this blocky thing that moves of course it will depend on your performance and what you want to do what you want to have some drag some lead with the arms that's going to be all different again depending on your own animates but the big pitfall is that when you move your arm that A the wrist stays put it's kind of hard to actually do this and that it moves in a straight fashion so elbow watch out cut wrist watch out straight path watch out it has to have arcs and as you move your forearm the wrist is going to be somewhat aligned depending on your actions depending on your acting choices with that forearm but you don't want again that cut line between the forearm and the hand so as you move like this he's happy about this you not only have the hand following the forearm but now you have an arm when the arm goes up and down this is of course a pain to do when you animate with ik arms because you can move this around i want to spline this but it's you can see this it's still not going to be pretty that's just the downfall of an ik arm you're gonna have to look at your tangents you might have to set more keys and more breakdowns and in between to make this work of course you might say well why would i do this why not just do this into fk i take this and just move it down and here we go this is a free way of doing nice clean arcs absolutely but this is again not a ik versus fk this is if you have to use ik for whatever setup again it's resting your pushing then you have to move some from one pushed and kind of somewhat locked position to another push for instance it's going to be also pain to switch from ik fk fk ik so you might as well stick with ik and this is why i'm showing you this because if you have this moment where you go from an ik position to another ik position you have to make sure that it still moves in an arc just like it would with an fk arm and it's tricky to do and i'm saying this is easy i'm very used to animating a lot of it in ik because of the rigs at work but it's still a pain so you can always draw on your screen that that's the arc that it's supposed to be you can do something rough with with fk arms but you move that fk arm you can also parent the sphere through that wrist and then bake it out and then you see that sphere moving and that's the nice arc or whatever you want to track then go back to ik and then move it around the many ways we can kind of hack things around to make it work but again if you are in a position where you have to animate with ik because sometimes it's just better than fk and this will be for the other clip so if you are in that situation make sure that you always have arcs i think out of everything i said arcs are probably the biggest thing but closely followed is that the wrist stays too put so when you move your arm around make sure that the wrist doesn't have that like i said before that separation where all this is moving but if i do kind of a twisty thing like that that forearm orientation has kind of continued through that that hand to a certain degree like i said just to make this look less like an ik arm and again if you have an ik arm when you move your body around that ik arm is going to stay put so again think about if this was fk and i'm moving everything around like this that's a bit more natural you're still going to have some drag overlap or whatever lead depending on the acting choices but all that goes out the window once you have ik so sticky wrist watch out when you move elbows around that a there's some residual movement and translate but also if you move that elbow around that your wrist is not completely locked you don't have that clear cut and i know i'm repeating things but it's important and i really want to drill that into your brain as you animate with ik arms the thing about ik is that you can just pose out things much faster just moving around your poses and you sculpt your pose and then that's it and you want to adjust things you can do this you move your chest that arm stays put it's really nice to do some quick posing versus if you switch to fk and you move your chest around it's going to move that arm around and the arcs are all messed up depending on the rig some rigs have fixes for that but that's just kind of the pros and cons between ik fk which i'll get to in another clip and sometimes the ik arms kind of sneak into production sometimes it's just not you can see this in some movies we go like that's a bit too locked there or that wrist is a bit too locked compared to the forearm it happens it's just really tricky to do and you have to be really on top of it but it's just sometimes you're out of time sometimes the move just you you work on it just doesn't quite work it's not easy to do actually there's a clip that i want to show from an old test that they did for tron legacy this is not to bag on the test because the test was not supposed to be public i think it was leaked to kind of make the movie happen i can't remember what it was but this is just a moment where you can see that this is an ik arm where there's not enough influence in the hands compared to what the rest of the body is doing so if i show you this this is the clip here so as he swings around you can see this here especially once you get through here there's a lot of movement in here that doesn't quite continue past the wrist and you can see it especially here there's a lot of movement there there's no rotation there's no other influence there especially here you can see this there's a lot of elbow movement and nothing is moving here it's just very very locked again this is not to specifically bag on the enemy who did this but just every now and then you can see it in production this is just want to show you this is in a actual shot this is what it would look like and i'm not saying i can do this better i actually tried this a long time ago this is with my old rig i remember doing this for the students as a kind of this is how you potentially fix it and then i realized that this was too thick and i can't really wrap my fingers around so all that looseness here and that jitteriness that is not a good example of showing what it should be but the main example i want to show you is that as the body moves around that forearm and here the hand this orientation is still somewhat working together so as the body swings around this forearm is going to or the whole arm is going to move this way so it's going to pull this section and rotate it around you can see this here and as it comes out i can still see some moments where it sticks i'm not going to say what is this is an old animation i just failed when i did this years ago but that's kind of the influence that i would like you to try to get to so as this is moving around there's still influence here and you can pinpoint the pressure and the lock in this finger so again i would have to make this a lot smaller so i can actually wrap those fingers around so when you play this side by side you can kind of see what i was trying to go for with that fix there you go and i say it again watch out when you move elbows the wrist has to continue depending on the situation of course but you don't want it to rest or just be somewhere in the air lots of elbow movement wrist doesn't continue you have elbow movement on top of that and then this lock where the control just locks in space that's also an ik flag a flag as in you can tell this is an ik arm you move the arm from a to b it's in a straight path that's typically ik you need arcs to me these are the biggest ones once you fix that's gonna look a lot more like an fk arm but even with fk arms you have pitfalls like i said before when you move the chest and just takes those arms with it it's at that one unit type feel where it's too parented that's the pitfall of fk arms but again i'll do a clip about ik versus fk what to look out for and how to switch and look at the most common best practices basically but if you are a student and you're watching this please pay attention to those points and the next time you animate something with ik arms make sure that you address those points with the message or starting again i know students will get into that same trap of well i need to push something or pull i'm gonna use ik arms and then i will be the teacher going no no wait you gotta move this and do that so watch this i hope it helps any questions about it let me know in the comments so i can clarify things or bring it up in the next clip speaking of clip if you have a clip with ik arms and you want me to help you with that problem i have workshops you know that's the pitch you can sign up at any time link in the description with all information the workshops are open you can sign up and start whenever you want to speaking of start i mean speaking of time thank you for watching till the very end this was a longer clip so thank you for your patience and watching this whole thing till the very end and if you feel like this is helpful and you don't want to miss any of those clips feel free to subscribe and hit that bell button if you don't miss any of my uploads like i said and that is that the pitch at the end for my channel but thank you for doing so it helps with the growth of my channel and that is that thank you for watching and i'll see you in my next clip