Clarification on skeleton support

[jsonedecker]

I am seriously looking into buying an OptiTrack system and am trying to figure out if it will work for our needs. We are a small game developer and use custom skeleton rigs for in game characters. So I am trying to figure out if this system will work for us. We use 3ds Max 2008 and can go with Motion Builder if necessary.

Our skeleton consists of 23 bones plus another 48 for hands and face. I know this system can't track the fingers and face, so we'll do that by hand.

I looked at the sample bvh files and they are set up completely different than ours. So my big question is, is it possible to use this system with our skeleton... and if so how?

This is really the last point that needs figured out to make our purchase decision.

Thanks.

-John

[Jim]

John:

I hope that more experienced animators jump in to answer your questions. In general, we haven't had an issue with customers applying our skeleton motion to their characters, either through retargeting the optical data in MotionBuilder, or applying the BVH data to the standard character in Max. I know this will work in MB, as I have seen customers do it, but not exactly sure in Max, we need some real users to answer that.

[bsteagal]

John:

I've used files from Arena in Max via Motionbuilder without too many issues. I used them on a custom skeleton rig provided to me by e-on software in Max. This is what I had to do... (I might have to go back and do it again, to give you the exact workflow, since it has been a while since I did it, so hopefully I don't miss any steps. Also, if you are streaming to MB, I don't know how to go about that way, since I haven't done it as of yet... and my MB is an older version not supported by the Arena fbx plugin)

Export your skeleton from Max to Motionbuilder using fbx.
Import this fbx file in MB an characterize your skeleton (make sure it is in T-pose, save it as a file called, let's say, Max or somethng)
Import a bvh file from Arena and characterize in MB (again, make sure you t-pose, save it to a file called, lets say, Arena)

Once you have the base skeletons characterized, load both in your scene, click on the bvh skeleton, import the bvh file on to this. click on the max skeleton and tell it to draw it's animation from the other skeleton in the scene. Bake the animation to the max skeleton and export as fbx (animation only)

In Max, have your skeleton loaded and merge the animation file onto it.

That is the general gist of it, I could send you a detailed workflow and characterized skeleton for Arena if you would like... You can even send me your max rig and I could do this for you too..

you can contact me at bryan@kkstudio.us

Hope this helps

Bryan

[jsonedecker]

Thanks Brian. I think you pretty much gave me the info I needed and I feel pretty confident its doable and efficient enough for a game project.

We also discovered a way to bind our skeleton to a Biped control rig in Max, import a bvh to the Biped then bake that into the actual exportable skeleton and export to the game engine. That pipeline is a bit cumbersome as we can't batch the export so we need to manually edit the motion name for each one for the exporter. Doing all the dirty work in MB and merging to Max then batch exporting out of there seems like the best solution.

I would love to get that MB characterized skeleton if you don't mind, but I would prefer to characterize our own so that I can learn the process. Having a good example to compare to will help a lot.

Once I verify that I can get one of the sample bvh files onto a character in the game engine then I'll place my order!

Thanks!

-John

[bsteagal]

John:

No problemo... I'll include both, that way you can see each and how they are characterized... It is pretty simple really

Give me your email, or email me... and I'll send them to ya..

Bryan

[jsonedecker]

jsonedecker@blackfootstudios.com

Thanks Bryan!

[tvining]

Hi Bryan, it sounds like you know something about this skeleton stuff!

I'm creating BVH files using the Arena system to be used in Cinema 4D via the InterposerPro plugin. The motions I create in the Arena software look pretty good in their editor, but when I export to BVH and import the BVH into Poser or C4D they look jittery in places. The guys here at NP suggested that it might be a problem with improper scaling of the BVH to the Poser skeleton.

So I guess my question is: does BVH have a native "size" associated with it? I notice in the Arena software there is the option to scale the BVH upon export, but what does that really mean? And if there is a native size to the BVH or Poser skeleton, is there any way to find out what that is? Also, from the posts in the thread, it sounds like there's more to it than just size--what is MotionBuilder doing when it "characterizes" a skeleton?

Also, one more question: is MotionBuilder the only place I can do this kind of high-end scaling, or is there some simpler (that is cheaper!) utility out there that might help me?

A lot of questions--sorry--but I'm really scratching my head over this stuff!

Thanks--Tim

[bsteagal]

Hi Tim:

I'm sorry I haven't responded to this, I've been a little busy lately.

The characterization in Motionbuilder is basically formatting the skeleton that you import into the structure that MB understands... basically you are remapping (renaming) the joints to the naming and skeleton structure of MB, that is all really.
I haven't tried any other utilities, but there might be some out there. House of moves has a utility called Diva that you can download, I haven't tried it though.. and there is another one.. called Lifeforms Studio 4.0 by Credo Interactive that I've heard some say is very good..

Now in regards to the "native size" of poser files..I have noticed that when you import a bvh from poser into MB, the resulting skeleton is very small in comparison to the one from Arena or other apps.. but let me go back and look at this again for ya.
I've had some jittery problems in Poser too... but I'm not too sure it is caused by improper scaling... let me go back and test and see if I can find out anything..

Bryan

[tvining]

Hey Bryan,

No problem--I understand "busy"! Thanks for for the tips, and anything you can find out I'm sure will be useful.

Thanks again--Tim

[bsteagal]

Tim:

I've been playing around a little... I've been experimenting with exporting a 1 frame bvh file from Poser to Motionbuilder with different default measurement settings from Poser (where you can setup whether the poser scenes are using Poser native settings, centimeters, inches, etc) to see if this will influence the scale of the skeleton in MB. My results are this.. any bvh exported without the "scale automatically" setting, results in an unreadeable file for MB..

If you export the file with "scale automatically" regardless of what your measurement default, results in the same size skeleton in MB.

Now if your character is smaller in Poser, the skeleton will be smaller in MB...

Now, my arena skeleton in MB, is more than twice the size of the Poser skeleton... which only reaches about halfway between the knees and the hips...

Poser scale is so confusing... and any bvh file you bring into it will automatically be converted to this PNU "poser native unit"

Now, in MB, what you do is retarget the animation from the Arena rig to the Poser rig... theoretically, MB will retarget for scale automatically... Now, I'm going to see what results I get..

would you happen to have the files that are giving you problems? that way I can see exactly what you are getting and I can see if by doing this retargeting in MB we get the same results.. I'll provide you with the resulting bvh and we can see...

sorry for the long.. disconnected rant... grin lol

bryan