How can I animate an imported rigged FBX

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Lukesmith123
Posts: 19
Joined: 21 Oct 2013, 15:38

How can I animate an imported rigged FBX

Post by Lukesmith123 » 22 Oct 2013, 00:09

Hi,

When I import a rigged FBX model into Softimage, I have a model rigged with a skeleton of nulls in place of the joints of the skeleton.

How can I create animations using this setup? If I translate one of the nulls it is not constrained by the parent bone, is there some way I can generate a more useable rig from the skeleton?

Thanks so much,

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myara
Posts: 403
Joined: 28 Sep 2011, 10:33

Re: How can I animate an imported rigged FBX

Post by myara » 22 Oct 2013, 10:44

I don't understand your question.

SI bones are a little "special", so all FBX bones will be translated to nulls in Softimage but it doesn't change the fact they are deformers. You can use them to animate the model.

Personally, I only use SI bones to rig, and nulls to skin.

Now, FBX doesn't support complex expresion and constraints that are used in most rigs, so if the source was a rigged model it will most probably be broken. The null-bones will be OK though.

If the source is just a skinned model without a rig, it will work almost as good as it did in it's original software. Now you only have to rig it if you want to animate more easily. Use some auto rigger or something.
Lukesmith123 wrote:If I translate one of the nulls it is not constrained by the parent bone
I don't quite understand this sentence.
M.Yara
Character Modeler | Softimage Generalist (sort of)

Jho
Posts: 49
Joined: 12 Feb 2013, 07:57

Re: How can I animate an imported rigged FBX

Post by Jho » 22 Oct 2013, 14:49

myara wrote:
Lukesmith123 wrote:If I translate one of the nulls it is not constrained by the parent bone
I don't quite understand this sentence.
I think he meant that the nulls aren't in hierarchy, so when he tries to move one, the others won't follow.

Yeah, like myara said, exporting a fully working rig isn't something you can do with any program. If I was you and didn't have time to rig the model in SI, I would just put the nulls in a hierarchy. Then you can animate by rotating the nulls. IK's won't work, so animating a walk for instance would be kind of hard, but at least you can do some basic animation.

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myara
Posts: 403
Joined: 28 Sep 2011, 10:33

Re: How can I animate an imported rigged FBX

Post by myara » 22 Oct 2013, 14:57

FBX should be able to properly import/export the objects hierarchy, but I've seen some MAX models with very weird hierarchies like shoulders under the neck, maybe is something lke that?

Anyway, if you want to change the nulls hierarchy but keep your envelope and weights you'll need to :

Mute the envelope, Activate ChldComp, Reorder your nulls, Set Reference Pose, and unmute the envelope.

You could also save your weights in a preset file, remove your envelope, reorder your nulls, re envelope and reload the weights preset.

Or you could use my little script that does basically the same:
M.Yara
Character Modeler | Softimage Generalist (sort of)

Lukesmith123
Posts: 19
Joined: 21 Oct 2013, 15:38

Re: How can I animate an imported rigged FBX

Post by Lukesmith123 » 22 Oct 2013, 21:06

Thanks for the replies guys!

Sorry yes you are right, the nulls are in a hierarchy and I can animate them from their rotations. But I cant translate them obviously which makes it pretty difficult to try to create animations using it.

Is there any way that I can set it up to allow them to function more like a normal rig? Do I need to set up constraints on each null to "tether" it to its parent?

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mattmos
Posts: 445
Joined: 02 Dec 2009, 16:59

Re: How can I animate an imported rigged FBX

Post by mattmos » 22 Oct 2013, 23:43

If you want to animate in si using ik, you'd have to build a skeleton based on the null positions (snapping to them as you create the bones) which is your animation rig, then the nulls would be constrained to the bone rig.

Lukesmith123
Posts: 19
Joined: 21 Oct 2013, 15:38

Re: How can I animate an imported rigged FBX

Post by Lukesmith123 » 23 Oct 2013, 01:13

Oh I see that's so simple.

What kind of constraint should I use?

And do I need to toggle child compensation?

Thanks so much for the advice

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myara
Posts: 403
Joined: 28 Sep 2011, 10:33

Re: How can I animate an imported rigged FBX

Post by myara » 23 Oct 2013, 05:42

Like I though, it isn't a hierarchy problem, the "translation" problem Lukesmith123 was talking about was IK, and that's something you can't export/import with FBX, but I suspect that Lukesmith123's model isn't rigged.

To create a basic IK controller for legs and arms you'll need to create SI bones and pose constraint those nulls to the bones, and add a Chain Up Vector to control the knees direction. You don't need Child Compensation but Constraint Compensation.

An easy solution would be to use the default Biped Guide - Rig that comes with Softimage. That should be good enough to start.

But if you're at that level I recommend you to buy a book and/or give a good read at the manual.
M.Yara
Character Modeler | Softimage Generalist (sort of)

Lukesmith123
Posts: 19
Joined: 21 Oct 2013, 15:38

Re: How can I animate an imported rigged FBX

Post by Lukesmith123 » 23 Oct 2013, 20:50

Yeah good idea about the biped guide. Thanks alot!

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