Three Questions about Optitrack

[dtaylor112]

Hey all,

I'm new to the Optitrack forum and had a few questions about the software. I looked through the FAQ's but my questions are specific and pretty simple.

1. Has anyone used Optitrack with DAZ Studio models? I haven't graduated to 3DS or Maya (yet) and I'm using Daz/Poser. I've purchased BVH files before (from motion capture sites) and they worked about as well as I expected. Simply Imported the file and applied it to the model. Does Optitrack work the same way? (after creating the motions of course)

2. How easy/difficult is Optitrack to use for non-programmers etc. I'm an artist and I'm somewhat "Tech-savvy" but by no means am I a "techie" or someone who can look at C+ and understand what it means. Is this a sort of "plug and play" (so to speak) kind of deal?
I ask this one because the "boxing.bvh" file in the 'Support/Training and Tutorials' page looked like this when I opened it:
***
HIERARCHY
ROOT Hips
{
OFFSET 0.000000 0.000000 0.000000
CHANNELS 6 Xposition Yposition Zposition Zrotation Xrotation Yrotation
JOINT Chest
***

and I have absolutely NO idea what that's all about. Would I need to know how to manipulate this kind of code in order to get the bvh files to work? Or does optitrack export those motions to a file I can then import into my 3D program?

Looking forward to any help/info I can get.

PS: I spotted this motion on youtube(http://www.youtube.com/watch?v=iLsnXEVOTzM). How many cameras would it take to get this kind of motion and should I expect to get these kinds of motions straight off the bat?

Thanks all!

KM

[bsteagal]

Koan:

I'm using a 6 camera system mostly with Daz/Poser figures, and the bvh files work exactly the same as any you purchase. Many times they work even better! Your workflow would be the same... create the motion in Arena/Optitrack, export to bvh and apply to your character. I use poser a lot because I create short videos for church on a weekly basis.. and I don't have time to model my own characters... *grin*

The system is extremely easy to use.. it is pretty much plug and play in my opinion. You will have a learning phase of about a couple of weeks, but that will be mostly with getting the correct positioning of the cameras for your particular capture volume... getting the markers exactly right on the suit, etc (which is what took me the longest amount of time) The software itself is a snap. I think the only other thing that has a learning curve is the camera calibration... which sometimes can be a little tricky...but not hard by any means.

Bvh is pretty much a standard with most of the 3d programs out there... I've used bvh from optitrack in 3ds max, Poser, Carrara and motionbuilder... and you don't have to do anything to the files, just use as you create them. You will have to do adjustments depending on the characters.... For example... I did this character for my Children's church class, and I had to get with the manufacturer of the model to correct an issue where the animation was not scaling correctly for the hips...

http://www.youtube.com/user/kidzkornerstudio

The motions in that youtube video you mentioned could be captured with a 6 camera setup, although more cameras is always better, it all depends on what you can afford, get the most that you can.

Hope this helps and if you have any other questions, please let me know..

Bryan

[tvining]

KM,

1. I don't have the Optitrack system (yet, I still have questions), but I have tried out the boxing and tennis samples from this site on Daz models, and it seems to work pretty well.

One *very* important thing I learned, however is that you can't import the bvh file directly onto the Daz figure, since, for whatever reason, it doesn't seem to scale correctly to the Daz skeleton (this is not exclusive to Optitrack bvh, so I'm thinking it's a Poser thing), so you get a lot of foot skating, etc. What seems to help significantly is to import the bvh first onto the Poser "stick figure" character (they come in male & female), save that as an animation in the Pose library (with no morphs), and then apply that animation to your Daz figure. It's an extra step, but it really makes a difference--after years of fighting with bvh, and nearly giving up on the idea of Optitrack at all, since their sample files didn't look that good to me when I tried using them with Daz figures, I luckily stumbled across this bit of wisdom buried on a thread on the Daz site.

2. I don't think we're supposed to mess with that code too much. BVH seems to come in a few flavors that translate, or don't, depending on the program you're using. Cinema 4D, for instance, never seems to have a problem opening and playing a bvh file (at least as a skeleton), but Poser can be picky, and sometimes it's a platform thing. I had some bvh files that wouldn't run on my Mac in Poser--they were slated as "PC"-specific--but the only difference is that there were extra paragraph returns in the code that the Mac Poser didn't like, and--using a macro in Word--I was able to remove these returns and the file worked. Many, of course, never work.

If the boxing and tennis samples are typical of Optitrack, it seems like they'll work for Daz/Poser, tho I'm hoping for a few more samples where the character isn't jumping around so much so I can see more subtle movements with the Daz figures.

Hope that helps a little--Tim

Auroratrek

[tvining]

Bryan,

Do you have any examples of applying your Optitrack to human figures? The mouse is very cute, but it's hard to get a sense of "human" movement from it, and that would be great to see.

Thanks--Tim

[tvining]

PS: if you guys have any other general Poser/Daz animation questions, let me know--I've been fighting this battle for years by doing Poser animation by hand, so that's why I'm so interested in Optitrack--but many of the issues would still apply even with Optitrack.

http://www.youtube.com/watch?v=9HgobywmhkE

[tvining]

Bryan, I did have one initial question about your set up: how do you have your cameras set up--that is, how big is your circle (I'm assuming they're in a circle), how high are your cameras, and what is the effective size of your capture area? I'm going to have a hard time finding a 20' space like they recommend.

Thanks--Tim

[dtaylor112]

Hm... very interesting. Thank You for the information but I do have one question.

How did you apply the boxing/tennis samples to the Poser/Daz models? Are there specific steps you had to take?

Whenever I click on the boxing.bvh link I get code. How did you get that code (or file) into Poser/Daz? IS there a way to save it as a bvh file?

I'm so glad there're a few other Poser Users in this forum.

[tvining]

You get a page of code when you link, but just do a "save page as" boxing.bvh--that saves it as a bvh file. Then, in Poser, bring up your stick figure character and then import the bvh file. This puts the motion on the character. The movement will appear very slow, since it was captured at 100 frames/second or something like that, so you'll need to Retime the animation down from 1800 frames (I think it's something like that) to 600 (30 frames/second)--or to about 1/3 of the number of frames. Save this in the Pose library as an animation, then call up your Daz model and apply the animation to it.

[dtaylor112]

Just tried it.. this is sweet. Thanks a bunch. THis is real sweet. Lots of frames but realy sweet.

That animation was exported using optitrack yes? I may need to start with 6 cameras.. hope they look that cool and fluid

[tvining]

Pretty cool, huh? And much cleaner than a direct import. Those files are supposed to be right out of the system. I imagine they were using 12 cameras. I'm still a little hesitant, and I'd feel better with a few more samples of more subtle movements, but maybe the only way to see if this thing really works for what I want is to just bite the bullet and order it. They have a 30-day return policy in the worst case, but I'm really hoping it wouldn't come to that, since just getting ready for the system would be a lot of work and expense (like getting the suit, etc.) Good luck!

--Tim