smartbone action - object makes a jump on main timeline

[saintbe]

Hi fellow animators,

I've been experimenting with AS10 and have an issue using smartbone.

I have a pair of cycling legs and when I enter my smartbone actions the bending at knee level looks fine.
However, when I then goto my main timeline I notice that the lower leg object makes a jump at some point.

From the looks of it it seems that the jump happens when the upper leg bone reaches a certain angle ... not sure why this is happening.
There are no angle constraints on either of the bones.

For reference I added a youtube video to demonstrate the behavior :
https://www.youtube.com/watch?v=NvBOhE1t4go

I would really appreciate if someone could point out my mistake.
regards,
-KW.

[dueyftw]

I'm not sure, but it looks like a smart bone action kicking in at that point of the the rotation. Do you have a smart bone action on the bone causing trouble? And dose have layer movement?

Please post file so I can take a look at it.

Dale

[saintbe]

Hi Dale,

Thank you for the prompt reply ! Much appreciated !

I cleaned the file a bit and saved the relevant part for download.
You can download it here :

https://www.dropbox.com/s/9d2vsij1r2w5tqr/legtest.anme

To see the issue, just go to any random frame on the timeline and move the target bone up (make sure the upper leg bone moves up when you do). If you move it high enough you'll notice the lower leg part jumps out of place. That does not happen if you play around in the smart bone actions themselves.

Alternatively you can also grab the hip bone and move it down ... if you move it down enough you will see the same thing (as soon as the upper leg bone reaches a certain angle the lower leg part jumps out of place).

I hope you can see what I am doing wrong.

Thanks again !
-Kim.

[dueyftw]

I think the target bone is the problem. If you can animate with out it, just delete it. Just why I'm not sure.

Dale

[saintbe]

Hi Dale,

Thank you for the info.
True… removing the target bone resolves the bending issue.

However, I need the target bone because it allows me to move the hip bone down.

Still trying to figure out why this is happening … If I find it I will update this post.

In the meantime, if anyone else likes to have a look


---------EDIT BELOW----------
Moving the target bone down and pointing the foot bone (as opposed to the lower leg bone) to the target bone also solves the bending issue in the knee … the problem in doing so is that the foot bends funny if I take the hip down… so I am looking how to fix that atm.

Thanks again.
-Kim.

[funksmaname]

I think you may have to set the foot to 'independent angle' so it doesn't bend funny.

As far as your leg snap - I'm not sure why, but when the thigh is brought up to a certain point your shin bone seems to flip - it goes from 147 degs to -212 in 1 frame, this is triggering your 2nd smart bone.

You might want to try starting with the leg out straight - then you only need one smart action for bending it inwards. You could also try using a single smart bone from one angle to the other...

I don't know, but this old video I made might be useful:

[saintbe]

Hi all,

I managed to fix it ...

I added another target bone for the upper leg part.
I placed the target bone high enough and that will prevent the snap from happening when I bend the leg up.

Here's a small video of the test I made :
https://www.youtube.com/watch?v=bffbvU4MUjU

I don't know why I had to do this but it gets the job done.

Regards,
Kim.

[heyvern]

Okay... I wish I could explain what's going on here a little better. It's not exactly clear.

Target bones are very new. They can have some "interesting" behaviors when associated with smart bones that haven't been completely figured out and resolved.

What happens deals with the rotation of a bone that is pointing to a target when the target is "pulled up" past the "end" of the aiming bone. This can cause a sudden "flip" in the rotation. An extreme negative or positive value in the rotation that isn't visible because it's the "same" rotation but sort of opposite. When a smart bone is added to this it can completely break that smart bones key frames when the bone rotates like this. A way to avoid this is to never move the target bone "below" or less than the length of the aimed bone. This doesn't work well, because the target bone movement is linear. You still get pops.

I have a new, really awesome rig using target bones that I've been working on for a couple of weeks and made some interesting discoveries that might help with smart bones and target bone issues like this.

One cool trick I found... don't put the smart bone action on the actual bone that is being rotated and scaled by a target. That is where all the trouble starts. For some reason the bone manipulated by a target behaves in odd ways.

I use an extra bone that is a parent of the aimed bone in the setup. In this case it would be another bone that is the parent of the shin or calf bone. The shin or calf bone would be set to "0 0" position. It's has the same origin.

Then I set the Angle constraints of the shin/calf bone to "0 0" in the bone properties drop down. This forces that new extra parent bone to rotate instead of the actual shin/calf bone. For some reason the "flip" doesn't happen on the new this extra parent bone. It sort of stops the bad behavior. Like a teacher in detention or a security guard at the mall .

This "extra" bone would then have the smart bone actions to move points instead of the ACTUAL shin/calf bone. You don't have any rotation of the actual bone since it's Angle constraints are now 0. Only the new parent bone rotates because it is being "pushed" around by the child bone that is aiming at the target. They both have the same origin so it works like a regular target bone set up.

I've found that using extra bones in the hierarchy can overcome many of these issues. The trouble is... it's really hard to describe. I've tried to do a video tutorial several times and it just feels more complicated than it is. The tricky part is keeping track of the parenting.

---

My new rig is freaking off the hook. Will be posting download and tutorials in the next few days.

It allows for complete and total control of all the joints independently. Instead of a target bone "chain" that moves all the connected bones, you can control each part separately. Drag the hand target and only the forearm rotates. Drag the elbow target and the bicep and elbow move but not the hand. Rotate the bicep and the whole arm rotates. You can drag a target bone for "scaling" or "foreshortening" perspective of limbs, or ROTATE the target bone to get "circular" movement instead of "linear". Plus, all of the smart bones work perfectly without issues or popping with the "standard" smart bone/target bone set ups.

I love this rig!!!!!!!! It has everything I ever wanted in a rig and is so easy to pose characters. I can "rotate" the entire arm or leg in a "circle" (like when throwing a ball, or a walk cycle), then I can key the target bone to create "foreshortening" of the limbs for perspective. The trouble with target bones was that it only allows a "straight" linear motion. I needed to add in a parent structure that allows for "rotation" movement of the target bones. Another feature is independent joint targets. I can smoothly animate the location of the elbow/knee with no pops. I also figured out how to add in IK "squash" to limbs. Target bones only have IK stretching by default. This trick breaks IK squash and stretch a bit though. Still working on that issue.

Sorry for rambling... I keep seeing all these issues with target bones and smart bones and really need to get this info out there ASAP.

[saintbe]

That's some awesome info Vern !

I believe I understand what you mean and I will experiment with this in the coming days.
I'm looking forward to that new rig of yours … if it's anything like your previous rigs then I'm sure it's going to be impressive

I will be able to experiment with this in the next 3-4 days … so if it turns out OK I might post an additional video with the result by the weekend.

Thanks again everyone !
-Kim.