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View Full Version : bvh files and rigging: where to start


darshie76
03-27-2011, 03:11 AM
hi all

I have purchased some bvh files, and they work fine with some of the apps that i use (poser pro, c4d).

Now i was wondering how can i rig new models to work with these bvh files. Is there any kind of tutorial that can show how to start rigging a model not rigged, and make it kinda "universal"? So i can use the various bvh files from Mixamo and Animeeple for example, but also use directly bvh files and attach to them the animations without having to spend hours in tweaks?

I would really appreciate any help here; it takes forever to rig a character and the last thing that i wanna do is to waste time doing something that then will not work.

I wish that everything would be as easy as with poser, where you just transfer the morphs on a new character and you have to do nothing more than small tweaks to use animations from a character to another.

Thanks for the help in advance!

eek
03-27-2011, 05:34 AM
hi all

I have purchased some bvh files, and they work fine with some of the apps that i use (poser pro, c4d).

Now i was wondering how can i rig new models to work with these bvh files. Is there any kind of tutorial that can show how to start rigging a model not rigged, and make it kinda "universal"? So i can use the various bvh files from Mixamo and Animeeple for example, but also use directly bvh files and attach to them the animations without having to spend hours in tweaks?

I would really appreciate any help here; it takes forever to rig a character and the last thing that i wanna do is to waste time doing something that then will not work.

I wish that everything would be as easy as with poser, where you just transfer the morphs on a new character and you have to do nothing more than small tweaks to use animations from a character to another.

Thanks for the help in advance!


BVH files essentially try to adhere to some basic rules (even though they can be changed) - axis order ZXY, Channels of data usually 3 and 6 on the root joint etc.

What's your source content tool you'll be using? If its anything like max you'll have to build firstly and importer/export for BVH and either mapping/transfering process, rig or both.

darshie76
03-27-2011, 05:49 AM
BVH files essentially try to adhere to some basic rules (even though they can be changed) - axis order ZXY, Channels of data usually 3 and 6 on the root joint etc.

What's your source content tool you'll be using? If its anything like max you'll have to build firstly and importer/export for BVH and either mapping/transfering process, rig or both.


I've got these from *********.com; got one of their packages with a great discount, and they look awesome on poser models, but i would like to make my own models and rig them properly so i can use the bvh files.

not sure what the "source content tool" is; you mean what software do i use to model and rig? (sorry but i am new at all of this; i'm learning trough video tutorials and books)

I wish that there would be something like a standard way to make a character so whatever bvh file you import it would work just fine :)

eek
03-27-2011, 05:35 PM
I've got these from *********.com; got one of their packages with a great discount, and they look awesome on poser models, but i would like to make my own models and rig them properly so i can use the bvh files.

not sure what the "source content tool" is; you mean what software do i use to model and rig? (sorry but i am new at all of this; i'm learning trough video tutorials and books)

I wish that there would be something like a standard way to make a character so whatever bvh file you import it would work just fine :)


Source content tool, yes max , maya etc ?


I wish that there would be something like a standard way to make a character so whatever bvh file you import it would work just fine :)

This is quite quite tricky, why because you can essentially make a bvh with any hierarchy (dragons are fun ;)) Different shoots can use totally different skeletons.

Additionally, your channels can be both 3 or 6, i.e joints in the hierarchy tend not to have position data in them (3 channels). This is a problem for weapons etc that need to be moved/dropped etc. So the data will be different.

Your own importer must firstly support, different axis orders and different channel orders. And your exporter if you write own must abide to the 1 endsite per chain rule etc.

What is the rule?

Crucially its a t-pose. All your data MUST have a t-pose bvh or be the first frame of the motion- i.e it must come with a standard reference you can map to - if not your essentially screwed as there would be no way to find the 'default' value of the skeleton.

I tend to work this way with motion builder, using several tools (python, max script etc) to get my skeleton t-pose to match the bvh's or vice versa. And processes to build a 1:1 match.

If the skeletons are identical, its pretty easy - if there not it gets 'creative' as to what you want to match i.e gross movement, torso, chest, ik controls etc - the further away the skeleton the more tricks you have to use to essentially build the missing data.


This gets trickier when your trying to come up with a standard model for mapping different data - i.e not just transforms, but objects, floats etc I'm looking into this atm.

Cactus Dan
03-29-2011, 03:53 PM
Howdy,

The method I use for this is to create a set of target Nulls for each controller of the rig. Then parent those targets into the imported bvh skeleton. Then I have all the IK handles and such constrained to both the controller objects and the target Nulls, so that I can blend between manual control and bvh control:
http://www.cactus3d.com/bvhBlend.mov

Since the bvh skeleton only needs position keys on the root joint of the skeleton, if there are position tracks on the other joints, I delete them so that I can adjust the joint chains' lengths to fit the pre-rigged character. The first thing I do is scale the imported skeleton so that the length of the leg joints match the length of the pre-rigged skeleton's leg joints.

Adios,
Cactus Dan

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