Question about Mocap and C4D


#1

Hi there.

I want to start working with some BVH files which come into Cinema with their own rigs.

Is it possible to apply the animation data on the BVH rig to Cinema’s built in character rig?

If so, how does one do that?

Thanks!

Joe.


#2

You have a mocap template in the character builder with various options (Daz/poser, Mixamo…).

Choose the most appropriate one then use a retarget tag to transfer the motion from the imported BVH to your character rig.

Note that the Daz/Poser compatible is only in R14 I think.


#3

Thank you Eric.

By the way, does anyone know of any good sources of free bvh files that I can use to experiment with in Cinema 4D?

Incidentally, BVH is the best format to use for Mocap data in C4D. Correct?


#4

https://sites.google.com/a/cgspeed.com/cgspeed/motion-capture

Carnegie mellon university mocap data


#5

Thanks again.

I guess you would need to make sure the two rig hierchies match (the BVH and the Character Object) to make the Retarget tag work.


#6

If you uncheck ‘use hierarchy instead of names’ then you can just make sure that the names of the controlers match, even if the hierarchies differ.
You will need to make sure the starting rotations are similar though.


#7

why BVH over fbx if I may ask?


#8

I’m afraid I don’t know the answer to that question. Perhaps someone else can elucidate.


#9

Bvh is a bad format. There is no standard really. The mocaptemplates bvh is for poser specifically(r14 ony). The one in r13, i dont even know what that was based off of.

FBX is often better but it all really depends on how you are getting the mocap files like what app are you getting them from? Because a bvh from poser is different from a bvh from daz. Same with fbx and such.


#10
  I'm not sure it's a question of Bvh being a 'bad' format, just that in general people tend to not use the exact same skeleton hierarchy in different studios. All it is is a hierarchy of joints really like FBX but people set them up differently depending on what capture technology they are using. 
  I've seen the same thing with FBX files, lots of variety in how they are set up, particularly in the spine joints (a lot of variation in how many joints for example), sometimes they have roll joints in the arms and legs, some times not etc etc
  
  With Mocap it's tricky to find consistent files IMO if you are sourcing them from different places, what I do is encourage clients to always source their motion from one studio only if possible, then I take the skeleton that comes from that studio, make a T-Pose version with no animation and then use that as the bind skeleton to skin the characters to and retarget the different motion files to. 
Unless you get really lucky and the skeleton hierarchy happens to match one of the preset skeletons that ships with the C4D character builder it's a simpler way IMO. Sure you can use constraints etc to patch things up but often that's more hassle, you don't get a 1:1 transfer and it doesn't really save any time in my experience.

For my money I’d recommend the Rocketbox characters, they are good quality, come in various LOD for the meshes and their mocap is generally pretty good quality. The advantage of sourcing the characters and the mocap from the same place of course is that the skeletons match exactly, so they are ready to go for retargeting. I made extensive use of them on a job a couple of years back and had very little issues with them.
I’ve played around with some of the free mocap files out there and to be honest a lot of it is pretty crappy… you get what you pay for I guess.

  Cheers,
  Brian

#11

Howdy,

With all the issues of getting mocap imports to fit existing characters, I’ve found that sometimes it’s easier to just use the imported mocap skeleton as a guide and then hand animate the character by matching it up in key poses.

Adios,
Cactus Dan


#12

A great point. On the one job where I did a lot of mocap cleanup, the ‘Disco Biscuits’ videos, I found the shots that turned out best were the ones where I pretty much dumped the mocap apart from a few poses and just redid it by hand. Often it’s just faster rather than fighting with what the capture gives you.

Cheers,
Brian


#13

Their models look fantastic. How do you get them into c4d? Their website only lists maya/max compatibility.


#14

Heh, touchy subject… at the time we were using R11.5 and the FBX bugs in that meant we had to switch the project from Cinema to Maya. That was a fun Christmas, talk about a steep learning curve, anyhoo it’s all good now I enjoy using both apps these days. :slight_smile:

  Rocketbox supply native Maya/Max files and FBX too though so these days in theory they should be perfectly usable in Cinema R13/14. I guess it might be good to ask for a sample to test out though. I know the project manager at the time on the job we were working on asked for that and they were very accommodating.

[Edit - now that I think about it - it may have been the case that they supplied the textured models as Maya/Max formats and just the mocap as FBX. Worth asking them I guess, they really were great characters for quickly populating a virtual world. Our ‘hero’ characters were created by a dedicated modeler and I rigged them, all of the NPCs were Rocketbox and driven by mocap.

  Cheers,
  Brian

#15

Hello,

Thanks for sharing your thoughts.

I’m not sure it’s a question of Bvh being a ‘bad’ format…

Agreed. I’ve brought in some BVH files before, and thought they looked pretty good to me.

     I take the skeleton that comes from that studio, make a T-Pose version with no animation and then use that as the bind skeleton to skin the characters to and retarget the different motion files to. Unless you get really lucky and the skeleton hierarchy happens to match  one of the preset skeletons that ships with the C4D character builder  it's a simpler way IMO. 

Sounds like a smart way to work to me.

 For my money I'd recommend the [Rocketbox](http://www.rocketbox-libraries.com/) characters, they are good quality, come in various LOD for the meshes and their mocap is generally pretty good quality. 

Nice resource to know about. By the way, what does LOD mean (polygonal density?)

I’ve played around with some of the free mocap files out there and to be honest a lot of it is pretty crappy… you get what you pay for I guess.

Yes, I was looking for some free ones to learn with. I wouldn’t mind paying for better ones for real work. Is there a good resource for high quality mocap data?

… they supplied the textured models as Maya/Max formats and just the mocap as FBX.

I’m wondering what the difference is between BVH and FBX for mocap data.

     Thanks!

#16

There’s no difference between FBX and BVH in what they do on the mocap side, it’s just a different file format.
FBX can be used to encompass more things, such as models, lights and so on… whereas BVH will only bring in joints and their animation.

As for hierarchies, it all depends on the motion capture technology used, so as Brian was saying, no matter the format, the skeletons will vary. Best practice is indeed to take one of the animated skeletons, then remove animations and make a Tpose out of it that will serve as your weighted rig onto which you apply the mocap data (through retarget tag or motion clips - which I prefer).

As for mocap libraries, it is indeed quite the challenge to find decent solutions.
I’ve worked with AXYZ characters and mocap libraries on a recent project and had some nice results: http://www.axyz-design.com/

But even here, I’ve noticed that their rigs didn’t match between their various libraries (looks like they used two different systems).
Not too hard to make two different rigs to support this, but still a pain when you consider you buy from the same studio.


#17

Thanks for the tips! Makes sense.


#18

Actually the biggest problem is indeed retargeting, especially with different hierarchies, sizes and FK to IK rigs… Unless the file is really pro, you can also have weird parasite movement on your character that aren’t really noticeable if you only see the animated bones.

Last time I had a short animation to do and I had a lousy mocap file (me and a kinect) which I actually only used as a “3D guide” to place key frames at the right timinng and locations on my arcs.

It was more like “tracing” than animation, but it did the job and looked ok, and the file was much lighter.


#19

Did you use their an(i)ma plug in for C4D?

Technically, I think that is more roto-scoping than MoCap… FWIW.


#20

I did a test, which looked pretty interesting, but didn’t try to export from Anima back to C4D. I see no reason for the process not to work, since everything is exported as FBX if memory serves well.
It’s a great crowd generator.

Reminds me I need to dig deeper and actually try a proper workflow with C4D.