basic leg rig

[Roger]

Ok, I'm going for a real simple IK leg rig. Here is what I've done so far:

 

1. Moved the left and right foot to the same level as the pelvis (hips)

2. Kinematically constrained the left foot to the left femur and right foot to right femur

 

When I move the hips, the feet don't move, which is good. However, when I move the feet, the legs don't follow. I know I must have missed something but am not sure what it is. Is there a constraint I missed?

 

I have 3 poses - one governs the fan bones in the body and neck, I'm not worried about that one.

 

The other 2 poses are set to on, so I'm not sure why the legs aren't following the feet. Seems like there should only be 2 poses, though, because while watching the "simplest IK leg rig" tutorial I noticed there is only one pose.

 

What am I missing?

[robcat2075]

You have 2. backwrds

[robcat2075]

Constrain the leg to the foot, not the foot to the leg.

 

 

The other 2 poses are set to on, so I'm not sure why the legs aren't following the feet. Seems like there should only be 2 poses, though, because while watching the "simplest IK leg rig" tutorial I noticed there is only one pose.

 

You're the one who made the poses, right? I dont' know what you were doing when you made them, but you do, right? What made you make an extra one? If you dont' recall , it's easy enough to open them in the PWS and look to see what's in them. What's in them?

 

It should only require one pose to contain the IK constraints for the two legs.

[Roger]

That's just it, I have the original pose that controls the fan bones. There were no other poses than this one when I started working on the legs.

 

Then, I created the new pose to deal with constraining the legs. I am not sure where the extra pose is coming from, unless I did something that created a copy of it.

[robcat2075]

But what is in the unexpected pose? Expand it... what's in it?

[Roger]

Back after a bit more of a break than I thought - been busy.

 

Anyway, I have 2 poses. One contains the fan bones, the other just has a relationship, but no bones associated with it. Not sure what it is doing.

If I right click on that relationship for pose 3 and choose properties I then get the pose sliders window and pose properties window. In pose sliders, there is a

Pose 1, but this pose does not show up in the Project Workspace. I take that back, it appears under User Properties, but its not clear what it does or what its controlling. If I click on it, all the bones light up.

[Roger]

I think I figured out where the extraneous poses are coming from - each time I add a new pose, even if I delete the previous ones, it tacks a number on the end and it shows up in pose sliders. Not sure why the old poses are still visible in pose sliders after deleting them from the Project Workspace.

 

I've taken a screenshot of my bones and constraints for the legs, maybe I'm missing something, I'm about to collapse so if someone sees something obvious, let me know. If I move the hips, the feet don't follow but if I try moving the feet, the legs do not follow the feet. I thought I set up the kinematic constraints correctly.

[NancyGormezano]

Not sure why the old poses are still visible in pose sliders after deleting them from the Project Workspace.

You must also delete the poses from the User properties

If I move the hips, the feet don't follow but if I try moving the feet, the legs do not follow the feet. I thought I set up the kinematic constraints correctly.

I am guessing you probably didn't turn the pose ON. You can turn the pose ON in the chor, or action (view/pose sliders). Or you can have the pose default to ON by setting it to ON in the User properties and then saving the model.

[robcat2075]

btw, you can rename those numbered poses to something more meaningful by RMBing on them in Properties>User Properties.

[Roger]

Nancy, thanks - that's exactly what it was. I had the poses turned on in the Cho, but when I went to Action mode to test them out, they were not on. I did not realize that they were off - thought if you turned them on in one spot they stayed on in another.

[Roger]

Ok, I am adding the left and right knee targets now. My nulls show up in both the actions tree in the PWS and in the bones tree.

 

Should the nulls only be created in Bones mode, and not in Action mode? I noticed in Rob's tutorial that he creates the nulls and positions them in bones mode, then does the constraints while in action mode. I think I may have messed up by creating the nulls in Action mode, and will need to do it the other way round.

[robcat2075]

Like all bone-like things, I would just add them as part of the regular model before I need them for a constraint. In bones mode.

 

Go back to the model before you started that step to avoid confusion.

 

btw, the constraints are done in a pose window, not an action window (although a temporary Action will appear in the PWS while you are editing teh Pose)

[Roger]

Is there some reason why I can't properly translate my nulls in bones mode? I click them to select, then hit the N key to translate. I try to move them, but nothing happens. Is it possible I locked them somehow? I am trying to move them in the Viewport, not in the PWS. For what its worth, they would move in Birdseye mode, but not in Front view, and then only on a diagonal.

[NancyGormezano]

If you are in front view and have selected the null with the translate manipulator (N) - then you can only move the null using any of the "exterior" handles - you will not be able to move it from the pivot point.

 

And yes you can move it in screen space in birds eye view from any of the handles or from clicking anywhere in the window.

 

It's just the way it is.

[Roger]

Nancy,

 

Thanks, I finally have my nulls in position. I should be using Kinematic "aim-at" constraints to aim the thighs at the knee targets, right?

 

Roger

[Roger]

Should I be editing my existing relationship I have and adding the aim-at constraints for the knee target or should I creating a new realtionship? If not, in what situations do you want to create an entirely new relationship? Or are all constraints added to single relationship (or would it be better to say all constraints of a certain type are added to a relation ship - for instance, all leg constraints are in one relationship, all arm constraints in another relationship, etc.)?

 

I successfully constrained the thighs to the knee targets, I'm just curious how it works, I guess.

[Roger]

One thing I noticed from Robcat's video was that when he did the aim-at constraints for the knee targets, the legs bent slightly at the knees. When I did mine, they did not do that - wonder if I missed a step? Or, maybe since my character has such short legs they don't behave the same way?

[HomeSlice]

in what situations do you want to create an entirely new relationship? Or are all constraints added to single relationship (or would it be better to say all constraints of a certain type are added to a relation ship - for instance, all leg constraints are in one relationship, all arm constraints in another relationship, etc.)?

 

In order to answer that, you must decide what you want your rig to do.

 

For example, if you want to be able to switch between IK and FK legs, you should put all those constraints in a separate relationship so you can switch that pose on or off without affecting the rest of the rig. If you want to be able to switch between Ik and FK arms for *each arm*, then you must have a separate pose/relationship for each arm.

 

The more granular control you want over your rig, the more individual relationships you will have.

 

Constraints which will always be active can all be placed in the same relationship, but eventually you will develop your own way of organizing sets of constraints to help you troubleshoot issues and stuff. Just jump in, rig a dozen characters, and discover your own preferred way.

[Roger]

One thing I've noticed, I don't seem to be able to rotate my leg bones, either the thigh or calves now. I wonder if I screwed something up when making the knee targets?

The feet don't follow the hips, which is good because they're not supposed to. And the knees bend if I translate the hips down. But If I try to rotate the leg bones now, they don't seem to do a whole heck of a lot.

 

Also, I can't figure out where the heck all these extra poses I have came from. I know I've deleted them at least once. Seems like when I edit a relationship or add a new constraint I automatically get a new pose?

 

Not sure if anyone will be able to tell anything from looking at a screenshot of the PWS.

[mtpeak2]

When using the knee target, you shouldn't have to rotate any of the leg bones. You should still be able to use the roll handles though.

[itsjustme]

The more granular control you want over your rig, the more individual relationships you will have.

 

I've never heard it put that way (or I don't remember it)..."granular" nails it, Holmes. Sorry to go off on a tangent, I just liked that.

 

You're getting great tips from Holmes and Mark, Roger.

[Roger]

Here is a screengrab I took. The legs look like they are moving properly, but I can't find the roll handle to rotate the leg bones. I hit R to go into rotate mode, I get the rotate manipulator but cannot rotate the legs since setting up the knee target. Mtpeak pointed out I should not need to do this. I thought the roll handled was the little line with the square on it pointing towards the knee? I can rotate that, but can only rotate left to right and not up/down. Left to right is of course the wrong way, unless I'm animating a horrible knee injury.

[mtpeak2]

The "aim at" constraint will not allow you to rotate the leg, only on the Z axis. You need to animate (translate) the knee target to position the leg.

[Roger]

Hang on, the upload must not have worked.

[robcat2075]

Nancy,

 

Thanks, I finally have my nulls in position. I should be using Kinematic "aim-at" constraints to aim the thighs at the knee targets, right?

 

Roger

 

An Aim-at constraint.

 

There's no such thing as a kinematic aim-at constraint. There's an Aim-at constraint and there's a Kinematic constraint but they are two different constraints.

[Roger]

Here it is. I am pretty sure I made the thigh aim at the knee, not aim roll at the knee. (I had to zip the file because it wouldn't let me upload a flash file)

screengrab_0_.zip

[mtpeak2]

Can't view the file.

[Roger]

Its a flash file. I tried to record a .wmv file but I'm using this freeware video capture thing, it doesn't seem to want to save anything but flash files.

[Roger]

Here is the file as an .avi file. This is the 3rd try, 2nd try I was trying to upload an uncompressed file and it was taking forever.

bone_test.wmv

[Roger]

Nancy,

 

Thanks, I finally have my nulls in position. I should be using Kinematic "aim-at" constraints to aim the thighs at the knee targets, right?

 

Roger

 

An Aim-at constraint.

 

There's no such thing as a kinematic aim-at constraint. There's an Aim-at constraint and there's a Kinematic constraint but they are two different constraints.

 

You are of course, correct. I have no idea why I wrote that the way I did. Tired I guess.

[robcat2075]

We get worried when when people use features that aren't there

[HomeSlice]

Here is the file as an .avi file. This is the 3rd try, 2nd try I was trying to upload an uncompressed file and it was taking forever.

It looks like you have a Kinematic Constraint on the lower leg bone (with the foot bone as the target). If that is the case, then you must move the foot bone in order to bend the leg.

[Roger]

So just translate the foot and the leg should bend accordingly. I will give that a try.

I think I am going to use a pre-built rig on the dragon, I'm glad I gave this a shot but rigging is definitely my least favorite thing to do, and I can see that the dragon is going to be a nightmare to set up even with a pre-built rig.

[Roger]

Ok so everything on my penguin is more or less rigged now. However, when I try translating the foot in an action, it doesn't move the leg. The foot moves away from the leg, stretching the splines behind it like taffy.

 

The left foot is kinematically contrained to the left calf, right foot kinematically constrained to the right calf.

My left thigh is constrained to aim at the left knee target, the right thigh is constrained to aim at the right knee target.

 

The right foot and left foot are currently children of the Root bone (not the default model bone but a dummy bone I created). Should they not be children of the calves?

I thought I removed them from that hierarchy per Robcat's tutorial so that the feet would not follow the pelvis.

 

What am I missing here? I must have jazzed something up somewhere along the line.

[robcat2075]

Ok so everything on my penguin is more or less rigged now. However, when I try translating the foot in an action, it doesn't move the leg. The foot moves away from the leg, stretching the splines behind it like taffy.

 

The left foot is kinematically contrained to the left calf, right foot kinematically constrained to the right calf.

My left thigh is constrained to aim at the left knee target, the right thigh is constrained to aim at the right knee target.

 

The right foot and left foot are currently children of the Root bone (not the default model bone but a dummy bone I created). Should they not be children of the calves?

I thought I removed them from that hierarchy per Robcat's tutorial so that the feet would not follow the pelvis.

 

What am I missing here? I must have jazzed something up somewhere along the line.

 

 

First guess... you don't have the pose that contains the constraints turned ON

 

Best option... turn it on in the model and resave the model. Then it will be on by default every time you use your charcter.

[Roger]

Ok, you were right, poses weren't turned on. Doh. I saved it with the poses turned on like you suggested so that will no longer be a problem.

If I translate the hips too far up, though, I still get the stretchy taffy feet. This is supposed to happen, right? Also, if translating too far down, the calves

pass through the feet causing the geometry to stretch.

[robcat2075]

Ok, you were right, poses weren't turned on. Doh. I saved it with the poses turned on like you suggested so that will no longer be a problem.

If I translate the hips too far up, though, I still get the stretchy taffy feet. This is supposed to happen, right?

 

I presume the feet controllers are not children of the hips and that is the correct arrangement if you are doing something like my simple leg.

 

With IK legs you will need to manage the feet so they are appropriately placed. If you've posed the hips so that the legs don't reach the feet anymore... move the feet so that the legs can reach them again.

 

On a rig like TSM2 the feet will stay attached to the legs if you move the hips too far away, but this still leaves the foot controllers behind and causes the legs to be unnaturally pulled tight. You would still need to properly position the foot controllers so that the legs are appropriately posed.

 

There is no animation situation where you would ever allow the legs to be pulled tight by a too distant foot controller... because it looks odd.

[Roger]

I think I am probably better off leaving well-enough alone at this point and moving on to rigging my dragon. My only concerns with my rig are that if I do

screw up the placement of the feet, there are going to be odd fluctuations in the legs over time.

[Roger]

Robcat (or anyone else for that matter):

 

Anything you would suggest adding to this rig that would make for easier animating?

[robcat2075]

Robcat (or anyone else for that matter):

 

Anything you would suggest adding to this rig that would make for easier animating?

 

I dont' know what all you have in it.

[Roger]

Well, flippers are FK. Leg rig is your basic IK leg rig w/ no modifications. Bones that make up the torso don't have anything special done to them, other than the fan bones (but I may have removed most of those when I was experimenting and found CP weighting worked almost as well).

[robcat2075]

My advice would be to do a few short tests of the sort of things your character does and see how that goes and post those.