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CB_3D
10-12-2005, 08:07 PM
:help:

A quick question. What type of foot setup is considered to be the best one for a human/oid character these days? The easiest to animate and most stable in IK behaviour?

Thx

Werner
10-13-2005, 01:01 PM
The "reverse foot rig" works well, and it's easy to set up as well.

do a search on this forum...I'm sure there are allot of tutorials on how to set it up.

Surrealist.
10-13-2005, 03:23 PM
Also look at Timothy Albee's simple set up. For charater animation I have worked up a simple method of animation for walking and so on that keeps the foot from going through the floor.

No expressions. No extra nulls other than nulls- not part of the rig - for positioning. All with key frames and not many of them either - as you might think. This alows for simplicity of animation with complete flexibility of movement on all axis.


This rig is just FK from the foot down to the toes(two bones). The Foot Bone has a null parented to it that is a goal object for the calf bone that is the end of a two bone IK chain (Thigh and Calf).

Simple set up.

Sorry for the picture. Something seems to have happened to the path tool display in 8.5. I was planning on being able to show the actual keyframes. You can see the path anyway.

Also you can see the two nulls used for positioning the foot. I move them into postion as needed once I set the foot down.

If you are interested I could post more details on the animation sequence.

CB_3D
10-13-2005, 05:38 PM
Surrealist, that sounds interesting. So, how exactly do You limit the Y-axis without plugs or expressions? Could You describe Your foot/leg setup in greater detail?

Thx a lot

Surrealist.
10-13-2005, 07:10 PM
It has mostly to do with using the TCB controls in the graph editor and knowing though experimnet wich keyframes will work. It took me three days of solid work to get all of the bugs worked out of the walk cycle, but once I got it it was simple.

There is a proton video somplace I think at Kurv where he goes through some similar steps - I saw this after the fact but he does not go into the detail for the foot movement.

Basically you first move the feet to thier postion on the direction of travel - say the z and move the rest of the body along to folow. So the model slides along as if on skis. Then you select the z curves in the graph editor and put the tention to 1. This stops the sliding

After this is done then you raise on the y between steps only to get that motion and then set the tension to 1 on the frames where the feet touch the ground. This keep them from sinking yet keeps a smoth curve between.

Then using nulls as references I place them at the toes or the heel depending on which part of the step I am working on and then I rotate the foot and the toes and then move the foor up or down on the y to keep them placed above ground. I keep this action fairly simple with ony a few keys. But I constrtain the slipage underground by using the tension setting in the graoh editor for the y and z movements.

If I get time and it seems useful I could write more of a tutorial but basically you use those nulls to keep the foot where it is on the z and use the grid as reference to keep it in place on the y. You can figure out a working method from there most likely. The thing to remember is keep it simple. Use the graph editor to design the curve. The path tool was a great help but now I can't see it in 8.5

Anyway the hole point of this method for me above others is complete flexibility while animating to keep the character free for any kind of movement and keep the rig simple.

I then used these principles to figure out a cyle of going up stairs. This way the rig will work on any kind of terrain and you can make it dance up a hill whatever.

Hope this helps.

EDit: Oh also that picture I put up there with the schemaitc view was so you could see the hiearchy/goal set up.

ericsmith
10-13-2005, 10:56 PM
The rig I use isn't technically a "reverse foot" rig, but it works the same way.

Here's how it works:

Starting with IK, there's a small vertical bone in the ankle that is the IK goal for the leg. The Ankle goal null is the goal, and it is rotated straight down in line with the small ankle bone. The bone is set to "match goal orientation".

Working down the foot, the ankle goal is parented to the Heel Rotator goal, which is placed at the ball of the foot. So when you rotate this goal, it effectively lifts the heel.

The Ball goal is set as the goal for the toe bone. No IK, but again "match goal orientation" is turned on. Like the Ankle goal, you'll need to rotate the null to the point where it is pointing the same direction as the toe bone. This keeps the toe pointed forward even when the heel is lifted.

The Toe and Heel goals are simply parents of the structure to give different pivot points. Here's the parent relationship:

Heel
Toe
Ball
Heel Rotator
Ankle goal

When you want to move the foot, move the Heel null. Rotating the heel null will of course pivot the foot on the heel. You can pivot the foot from the toe or ball as well by rotating either of those two nulls, but I don't use those nulls very often. As I said earlier, rotating the Heel Rotator on it's pitch will lift the heel, but keep the toe pointed forward, giving you foot roll control. You can hide the ankle goal, as it should never be animated.

This foot setup is completely stable, and very easy to animate with. Having pivot control of the heel and the ability to roll the foot on the ball makes creating a walk animation really easy.

Eric

Surrealist.
10-14-2005, 12:54 AM
Hey I am going to check this one out too as an option. I had seen something similar in a tutorial here on rigging. Did you get it from that?

Anyway nice explanation. I might play with this idea myself as I may be able to incorporate that in my rig. :)

ericsmith
10-14-2005, 08:56 AM
I think I was first introduced to the 3-point foot setup by Todd Grimes at a character animation seminar many years ago.

I've tried several times to redesign the rig with the IK goal at the ball of the foot, so the heel lift would be automatic, but I keep coming back to the stability of this design.

Although I have to say, this thread has got me thinking about the concept again, and now I have some new ideas I want to try. There goes another Saturday morning...

Eric

CB_3D
10-14-2005, 12:40 PM
All very good stuff. I remember the Todd Grimes setup and basically itīs what i use right now with one or two little variations.

Where can "Timothy Albee's simple set up" be found, btw?

Thx for all the great input, this thread could be an important ressource if it continues :thumbsup:

CB_3D
10-14-2005, 01:57 PM
Oh, and has Protonīs footsetup already been made publicly available? The one from HDRI?

Surrealist.
10-14-2005, 02:41 PM
All very good stuff. I remember the Todd Grimes setup and basically itīs what i use right now with one or two little variations.

Where can "Timothy Albee's simple set up" be found, btw?

Thx for all the great input, this thread could be an important ressource if it continues :thumbsup:


Well to proton's I don't know. But he has a free walk cycle video on Kurve I believe.

TA' version is in his book LW 8 Character Animation, which I recomend for many reasons other than his just rig set up - which by the way is extremely simple. I have managed to also set up his rig with bones and no weights using hold bones. His other stuff on animation is worth the price of the book many times over as well.

The foot set up is easy:

from the thigh down it is.

Thigh Bone - Parent is the knee bone ( a little bone used to roate bank only that sits in the hip.) Ik is terminated there (unnaffected by decendents)

Calf Bone - Parent is Thigh Bone

Foot bone pivots off the point of the calf bone. A null is parented to it (and centered at the foot bone's 0,0,0,. This is the right/left goal,

A bone that also comes off of the exact pivot point that the foot bone shares - called the right/left leg puller is parented to the calf bone.

This ends the IK chain foir the leg.

The legg puller bone uses the leg goal null as a goal object.

So in effect where ever you move the foot the leg IK chain follows but rotations and so on are of course FK on the foot and toes. Just that simple.

Hope the pic is clear.

CB_3D
10-18-2005, 08:24 PM
Has anybody been able to dependably plant a foot with fix in IKbooster?

ercaxus
10-18-2005, 09:32 PM
not me :(

Surrealist.
10-18-2005, 11:19 PM
I am not shure that is the right tool for the job. But here is some info oringinaly posted by dodgy that might help if you try it.

Quote:

IK boost is kind of a blend between traditional IK and FK. It's a lot like IK without Full-time IK on, in that the IK will work while you're manipulating it, but when it's being interpolated between keyframes it'll behave like FK, and may 'wriggle'
You can use what are called bake spots to get around some of this.

Bring up the Dope track when you're using the IKB tool. With your 'hand' selected, right click and drag out the area you want the BakeSpot to be and in the right click menu click 'Set Bake Spot'. The Bake spot is the period during which you want the 'hand' to lock in position.
A cyan area will appear along the dope track.

Go to the IKB Menu in the lower right, and enable 'Auto bind'. Now your locked hand should stay in position in that part of the timeline. When you start moving your parent around again, it may start to wriggle, and you'll notice when you first select it it may show extra keys. This is okay. Just go to IKB Menu>Commands>ReBindMotion All, and it'll fix the motion of the object.

This way you can get on/off/on again IK along the timeline.

If you want to pin a rotation of a hand as well as the position, fix a child of the hand as well, and LW will be constrained to using the fixed rotation.

SplineGod
10-19-2005, 01:00 AM
Has anybody been able to dependably plant a foot with fix in IKbooster?
The best/easiest way Ive found to dependably do that is use a mix of LWs IK and IKBoost. Things like match goal, orient constraints etc work with IKB.
For most rigs I use IKBoost blended with LWs IK this way. In fact its designed to. You can use bake spots and the bind command but I find it easier not to. :)
If you havent seen it the IKBoost DVD gives a good overview of IKB vs LW IK and will definately get you started.
Also in terms of foot rigs I usually find the simplest the best to use. Ive seen a lot of slick setups but usually are a pain to setup. Each type of setup will have its pros and cons. Generally I go for something simple to pose but easy to setup or modify if I have to. It also depends on who is using your rig. In the end its the animation that counts and nobody really cares about the rig except you or the guy using it :)