Rigging problems and solutions

Up until now I have been using IK Target animation, which works fine for the type of motion I've been going for.
IK Target animation is linear, all straight lines between Target Positions.

But let's say I want a different motion, perhaps a high kick like a can can dancer.
For this I need to describe a smooth arc and to do that with Target animation
all I can do is add more keyframes to smooth out the curve.

Spline Tracking is great for this type of motion.
Here's a comparison of both types. Can you see the difference?

arc_-compare.gif



It can be a good idea to plot your arcs with a spline to see them better.

plot_compare.gif

Another method of course is FK aka forward kinematics.
Remember IK is linear, FK is not. FK produces natural arcs.
Smooth arcs can make the difference between good and great animation.
 
It would be nice to have all rigging tutorials in one place. I usually copy and paste from the forum to a TextEdit file, but that gets cumbersome.
Every app has its idiosyncrasies so you can't always just follow a tutorial for other software.

Bob
 
Yes! At least they will all be in one place. Thanks for all your knowledge on this. I know general rigging and had put together a pretty nice rig years ago in Cinema 4D, but Cheetah is very different, to a certain extent and not as automated. I really think more Constraints would be a big help.

Bob
 
For my next post, I'm going to show how to combine both IK and FK to achieve smooth arcs.

To do this you use an IK Handle but without an IK Target.
You can still add an IK Pole to keep things pointing in the desired direction.
Note: Further testing reveals the IK Pole does not work without an IK Target
And I make use of the old Pose Tag to save the start and end positions of any motion.

I won't need any in between keyframes like with IK Targets, using the Key Hierarchy
setting I'll be keying the bones/joints themselves for forward kinematic animation.

rigseq.gif
 
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I like to break down motion/poses into two categories, regular and extreme.
Or those that don't cause gimbal lock and IK Flipping and those that do.

And I also look at each model part, whether it's a hand, foot, leg or
arm, each has it's own ratio of regular to extreme poses.

In other words, hands have a lot of extreme poses, but legs not so much.
The IK Handle, without adding an IK Target, can be used for
positioning as long as it's not in the extreme range.

The two methods that can handle anything are:
1- IK Handles with Targets and Poles.
2- Forward Kinematics.

I built this complex action one motion at a time.
• Little Finger D4- extreme pose but I was able to get there once with IK no target, should use IK w/Target/Pole or FK.
• Middle Finger D3- extreme pose, should use IK w/Target/Pole or FK.
• Pointer Finger D2- regular pose but custom bone positions, use FK.
• Thumb D1- regular pose, use FK to Global Rotate Palm 1 bone.
• Wrist- regular pose, use FK.

button-push.gif

I preshaped the bulges between the joints of the fingers of the model, and edited the Vertex Weight
to accentuate those bulges and the knuckles, to keep the fingers from looking like elbow macaroni.
 
Here's the jas file for the four finger hand if anyone wants to play with it.
There are two Takes, one with the button push keyframes and one with no keyframes.

Any IK Handles, Targets and Poles have been removed as they only serve to position
the fingers to be captured by the Pose Tag, which can then be used to keyframe.

hand_poses.gif


You can add your own IK handle to the end Joint of a finger and set the Length property of the 2D solver to 3.
Once you put the IK Handle on, you will be able to move that end joint to position the finger.
Then add it to the Pose Tag and then you can just move the IK Handle
to the next finger and so on if you want continue.

With the Key Hierarchy setting on, you can key the whole rigamarole
or individual fingers depending on which bone you select.
 

Attachments

  • Four finger hand jas.zip
    58.6 KB · Views: 125
Here's a video of me using IK handles and the Pose Tag to keyframe finger motion.
I had to make a custom window layout for this one.

Key Hierarchy must be on.

At the end I'm trying to copy and paste the first keyframe to the last for a loop.

 
When you have hierarchy on, does it just record changes? So, if you had an entire character and went to the root bone but only changed hand position, does it just record the hand?

Bob
 
bobziila said:
When you have hierarchy on, does it just record changes? So, if you had an entire character and went to the root bone but only changed hand position, does it just record the hand?

Bob
Click to expand...
No, for that you also need to turn on Only Key Changed Parameters
which is right next to Key Hierarchy on the timeline.

It won't work for the first keyframe so turn it on after you set the first one.
 
I’ve kind of given up trying to master rigging and animation because Mixamo retargeting works so well (at least until Adobe gives up supporting it) and I just don’t have the bandwidth. That said, the fact the C3D basically cannot deal with more than one figure at a time (and Martin is obsessed with rendering engines and not the UI so there is no prospect of improvement) is so crippling a limitation that I just don’t see the point.

i probably just come across as a bitter asshole these days… sorry.
 
podperson said:
That said, the fact the C3D basically cannot deal with more than one figure at a time (and Martin is obsessed with rendering engines and not the UI so there is no prospect of improvement) is so crippling a limitation that I just don’t see the point.
Click to expand...
What exactly do you mean by Cheetah cannot deal with more than one figure at a time? I don't know any other 3D animation software and I don't know how it is otherwise. What could be improved?

(I only ask because in my last short I have a Marty, 1 partridge, 2 doves, 3 hens, 4 blackbirds, 6 geese, 7 swans, 8 maids, 9 ladies, 10 lords and a worm in one scene. That is definitely more than one character at a time - But you probably mean something else. I just don't know what. 🤔 )
 
Lydia said:
1 partridge, 2 doves, 3 hens, 4 blackbirds, 6 geese, 7 swans, 8 maids, 9 ladies, 10 lords and a worm. 🤔
Click to expand...
* Whatever happened to the 11 pipers and the 12 drummers? Your countryman, Günter Grass, wrote one of the most brilliant novels on such a drummer...

Screenshot 2023-05-08 at 15.46.14.png
 
Lydia said:
What exactly do you mean by Cheetah cannot deal with more than one figure at a time? I don't know any other 3D animation software and I don't know how it is otherwise. What could be improved?
Click to expand...
I don't know what to say… you should get out more. Try some other 3D software. Or at least google 3D NLA animation or animating crowds or…

I still think Cheetah 3D is one of the best box modeling tools (being able to weight the sharpness of edges for subdiv would be nice, though). But the effort being spent on rendering relative to everything else has really taken a toll, and hasn't given us volumes or SSS or a bunch of other things that were much of the rationale for a new rendering engine.
 
ZooHead said:
Up until now I have been using IK Target animation, which works fine for the type of motion I've been going for.
IK Target animation is linear, all straight lines between Target Positions.

But let's say I want a different motion, perhaps a high kick like a can can dancer.
For this I need to describe a smooth arc and to do that with Target animation
all I can do is add more keyframes to smooth out the curve.

Spline Tracking is great for this type of motion.
Here's a comparison of both types. Can you see the difference?

View attachment 39316


It can be a good idea to plot your arcs with a spline to see them better.

View attachment 39317
Another method of course is FK aka forward kinematics.
Remember IK is linear, FK is not. FK produces natural arcs.
Smooth arcs can make the difference between good and great animation.
Click to expand...
I think that the animation pros I've worked with would simply say "use FK for something like that". If you just rotate the hip joint you get a perfect arc (this is, after all, how one does a high kick). You might use IK to manage the rest of the body adjusting to retain balance…
 
podperson said:
I don't know what to say… you should get out more. Try some other 3D software. Or at least google 3D NLA animation or animating crowds or…
Click to expand...
Cheetah can do what it can do and Martin does what he can do. He just has to set priorities. We all know that and we can use it or we can leave it. So I don't see why you are upset. Then just use Cheetah for modelling and use other software for animation. But I'm a little confused. If it's so easy to animate in other software that you seem to have, why did you give it up and use Mixamo? I use it from time to time too, but basically wouldn't consider it an alternative to animating.

However, this thread is about how we work with what we have, not what we don't have or what we could have.

You don't know what to say? How about just answering my question? At least now I know that by "more than one figure" you mean crowds. I don't need to google NLA. Of course, I haven't tried it yet, but I imagine it would be very handy. I agree with you there. But as I said, there are two possibilities and I have chosen the first. Which doesn't mean that I don't like to try things out - on the contrary. But that's another topic - at the end of the day, I just wanted to know what you meant.

Helmut said:
* Whatever happened to the 11 pipers and the 12 drummers? Your countryman, Günter Grass, wrote one of the most brilliant novels on such a drummer...
Click to expand...
Oh, they both exist, but there was neither the time nor the motivation to multiply. (Are more than 10 people already a crowd? Then it could be difficult with 11 anyway. 😉 ) And so they will probably die out and other creatures are just about to take their place...
 
Lydia said:
He just has to set priorities.
Click to expand...
I'm well aware of this, which is why I don't spend much time here any more.
Lydia said:
However, this thread is about how we work with what we have, not what we don't have or what we could have.
Click to expand...
One of the ways you can work with what you have is use different programs according to their strengths. Back when C3D didn't do any kind of motion-blur I spent a lot of time trying to work around the issue in Cheetah 3D and then gave up and simply rendered elsewhere.

Similarly, a bunch of us spent a huge amount of time trying to fake volumetric effects or work around the lack of SSS.
Lydia said:
You don't know what to say? How about just answering my question?
Click to expand...
I actually tried to list a bunch of ways animating both single and multiple figures is a huge pain in the ass and decided that it was just becoming a laundry list of long-running gripes.

Martin did implement the MIT automatic rigging algorithm virtually overnight when I pointed it out to him. Without that I think almost no-one would even bother persisting with character animation in C3D.
 
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