Help with animation (Carrara 5)

[Rowan]

I'm trying to create a robotic tentacle which is animated. Basic structure is a repeating pattern of sphere/cylinder/sphere/cylinder. Is it possible to set it up so that I have a repeating set objects that are ready set up with constraints, but can be moved around? Whenever I try and move them they jump to about -400, even when the X constraint is free.


EDIT: Hmmm. Seems to work fine now. Maybe because I had to free all dimensions, not just the one I wanted to work with, or it could have been the group structure. However, it still wont move as it's supposed to. Scaling also doesn't work at all, it simply moves the object about, even when I've checked the hotpoint. Anyone know why?

EDIT2: I can get round that issue by using a new group as a 'shell', but I still would like the know the reason for the errors.

EDIT3: Ok, no I can't. This is completely bugged. Going to have to give up and think of a new way.

EDIT4: What on EARTH is going in with the Carrara import function??? If I import something at a 1:1 ratio and disable scaling and auto position, why isn't it exactly the same??

[Rowan]

Ok, I'm now getting really fed up of this program. It wont import properly, it was released as compatable with Amapi, the new version of Amapi wont let its files near Carrara, the import on Carrara is VERY badly flawed, the constraints are even WORSE. And there's probably a whole load more that I don't even know.

[Rowan]

Ok, I got a sort of version working, I had to re-create in Amapi, I never realised that Amapi was so flawed. The placements work to 3 SF in the UI, but when you look at them properly, they're to 6 SF and often not the same as 3 SF, so I changed those to the exact values, exported to Carrara, got them back to the same size. I then set up the constraints required (Anyone from Carrara Dev team, PLEASE oh PLEASE make 3 boxes, one for each constraint and one for the angle... when you're constraining between 11 and -11, it's hell to select which you want to change. Text boxes please!) and then I set up a group to enclose the ready-made pieces. This group acts like an envelope and lets you move the objects inside it without the odd bug. Only problem is the tree gets really full very quickly and you have to be careful what goes where. I need to think up a naming pattern.

[Grendel]

I had worked on this some time ago here:
http://forums.polyloop.net/3d-work-p...-tuf-chic.html this uses an IK chain with ball joints with limited degrees of movement that track a helper object.

For a matrix style sentinel flying/swimming cycle just use a wave modifier with a sawtooth tweener cycle, I've attached a simple example file. If you're making a sentinel I would use a cluster of the "dumb" wave tentacles for propulsion and a few IK chain "hero" tentacles for grabbing stuff/acting.

Let me know if this is what you're after. You're right about scene structure as well, if you start doing large IK work, naming conventions are worth the effort up front.

[Rowan]

*Watches post go over head*

Right. I understand basically what you're saying...but have no idea how to implement it. I thought IK chains were used for deformation style animation, and that mechanical animation was best handled using manual movement. I've posted a 2 second animation of the test tentacle I did, seems alright. Watching the DVD again, they did exactly what you said. The 'swimming' sentinels have 'dumb' arms and lots, but the closeups have few and are properly done.

[Grendel]

IK can be used for mechanical and really has to be when cylinders and other feedback between components are involved. Look at any crane or digger and they have stabilizing arms pivoting from the movement caused from cylinders. This would be pretty hard to do without IK.

Here are two more looks at the Doc Oc rig and a hose example using IK to simulate it's flexing between two rigid parts. Let me know if it is clearer now.

[Rowan]

Ahhh! That's how you do it. So instead of moving each part individually, you specify 2 points, and then create a chain to connect them. Right :D I wondered how that was done. I'll give it a go now.

EDIT: How many bones were in that hose?

[Grendel]

That's correct set the limits for the joints and let the soft do the hard work for you. Once you set the limits it will obey the rules you give it.

15 bones in the hose

[Rowan]

Why does the 'wire' deform when I point it at something? Also I cannot get it to follow the object's movement. The final 'bone' points the tip when it moves, but nothing else.

EDIT: Solved the deform. Worked out it tracks to the hotpoint, just moved that around to solve that. But still wont move...

OH WAIT! It's a bug! If you type a number for the boom to rotate, the IK chain wont follow. But move it by hand and it will.

How can you remove all animation from a file?

[Rowan]

Success! Not very elegant, but it works. Now I just need to refine it and work out the best way of doing things, then work on making a linked chain of it. Can you give me a more in-depth tutorial of doing the linked chain? As in what the chain should be (seperate objects, one object etc), where to place IK bones, what kind of constraints etc etc.

Also, a tut on how to pick up an object would be good. I have an idea on both of these, but don't know if they're correct. I've managed to make a passable animation on a short linked tentacle, now to try and make it 'grab' something.

[Rowan]

Getting there, I've made a grab and scene for it, but I'm having problems directing the IK chain to go as I want. Are there any tricks for that?

[Grendel]

The file in my earlier thread link has a grabbing set-up and walk-thru.

[Rowan]

It's the 'claws' idea that I'm having trouble with. How should I set it up so that the claws don't get counted in the IK chain, but follow their path? Also, is it possible to force the chain to go down or up? When I shorten the helper object, it does down by default, even if I want it to go up, leading to virtual knots that require thought to undo...

[Grendel]

here is an explanation for the claws.

[Rowan]

Yeh, I'm just got to that conclusion, but how can I make the 'grab' look realistic? Is that the Rotation Manipulation thing that I have no idea what it is? I'm about to see if I can make it pick up a sphere.

[Grendel]

Select the first claw bone and rotate it, select the second one and rotate it....

[Rowan]

Ah. Ok. One problem I've come across is how do I tell the arm where to go? Say I want it to approach the object from the top, but it would approach from the side by default, how can I do that?

Also having some problems with the claw. I've set them to axis of rotation, but they deform as they rotate. Is there any reason for that?

[jawra]

HI
Grendel - your technique and explanations are clear and great helpful.
Rowan - can you attach some picture of your scene with claws and its bones visible - it seems to be problem with weight-painting of claws.
Here is .car file with rigged claws so no manual rotation is needed for closing and opening , just move target helper.Sample animation included.Analyse bone rigging and weight-painting. And have a fun.

[Rowan]

Here you go. It may be a problem with the way I've created the claw, I'm completely new to animation, and am only going on what I work out and what you people here tell me. I'm quite pleased with the result so far.

[EricD]

Originally Posted by Rowan

Also having some problems with the claw. I've set them to axis of rotation, but they deform as they rotate. Is there any reason for that?

I didn't read the whole thread... did you skin the object or did you just attach the parts to the skeleton?

Skinning will deform the mesh, which is ideal for organic forms and character animation.

Attaching will move the objects without deforming the mesh, which is great for machines, etc.

Download Thierry's tripod and check out how the members are simply attached to the bones.

Eric