How can I change position of optical data in MB?

#1

Hello everyone,

I’ve been a member for close to a year…but this is my first post! I hope someone can help me out!

I did a sucessful motion capture last weekend. The only problem is that I defined the ground plane in such a way that the Z-axis element of the optical data I have imported to MotionBuilder is rotated by 180 degrees!

In other words, my optical data describes a humanoid that is standing with his back to the viewer of the screen.

In order to use an Actor, I need the data to be facing the other direction!

I’m assuming I can use a constraint or something like that to rotate the Z-axis position data by 180 degrees.

Did that make any sense? And if so…can anyone help me out on that? I would be forever grateful!

Thanks!

digitizer

#2

Hi Digitizer,

you can simply grab the “c3d:optical” and rotate it like you want.

Maybe it is that what you are searching for!?

Diogo

#3

Hi Diogo,

Thanks for the reply.

The problem with simply rotating the data (believe me, I tried!) comes when you click the “Activate” button on the Actor Setting area.

Once you try to activate it, the optical data flips around back to the original position!

I can’t seem to find any other way…grrrrr!!!

#4

Do you have Keys on the optical root? Take a look in the f-curves editor.

If yes, kill them all and then rotate the optical root, that should work, if that was the problem.

Please keep me posted.

regards,

Diogo

#5

Besides, you can rotate actor (by hips) once you bring it into the scene. We always have markers facing 90 dergrees away from the actor, so we just rotate the actor. That works ok.

#6

I know you’ve already received an answer to your question, but I’m procrastinating, so here goes:

As far as I’ve experienced, you can map the Actor to a markerset in any direction/position you want. The +Z rule only comes into play once you’re ready to characterize your model.

Whenever I need to rotate our optical data, I do as Dioginho suggested, and use the optical root node to do whatever rotations necessary. Keep in mind though, that if you have multiple takes (which you most likely do), translations/rotations/scales to the markerset is evaluated on a take-by-take basis – which means you need to do the same for all your takes (if desired).

I normally go through all the takes, after mapping and activating the Actor, moving and rotating the markerset to default at the center of the stage facing down +Z. Just a habit that has proven to be time saving further down the pipeline. Especially since some of our stuff is used in game engines, it is a lot easier to have the placeholders defaulting to the same coordinates.

Enough blabbering, I hope you solved your problem anyhow :slight_smile:

Cheers

#7

gozzer,

Thanks a lot for your detailed posted. I have realized that you are exactly right (thanks to Dioginho etc all as well!). I can just use the optical root for rotation as necessary!

Unfortunately, I’ve realized how difficult it really is to set up the Actor to move according to the optical data. No matter how careful I am in scaling the segments and aligning them correctly in MB, the actor always comes apart at the seams – bodyparts flying everywhere!!

It sounds to me like you’ve (gozzer) gotten proficinet at creating actors in accordance to your optical data. I know my optical data is clean…but it’s really frustrating to have come this far and now I can’t even manage to employ a basic feature of MB (the actor) successfully.

If you don’t mind me asking, but how do you do it??

#8

I don’t really have any particular routine to the position and scaling of the actor, so it’s a little hard to describe. I can still try, though :slight_smile:

  • Start from the front view, moving the Actor (by selecting the pelvis/root) to the center of your marker cloud.
  • From the left/right view, move the Actor again to the center of the cloud.
  • At this stage, I would scale the pelvis to roughly match the hip markers.
  • Depending on the marker layout, I would move between perspective and front/top to rotate the clavicles/shoulders and scale the limbs and torso to fit your performer’s dimentions.

I normally don’t over-compensate on rotations when setting up the Actor, because limbs will more or less snap in place when you activate anyway. Keep in mind though, that you can make minor alterations to the rotations and positions of elements (hands, etc) after activating the Actor. Minor being the keyword.

As I have no idea of what data you have to work with on this, feel free to shoot me an email with your optical data, if you’re still out of luck. mocap@deakin.edu.au should do.

EDIT: I might add that I always map Actors and Characters to our performers’ T-Pose takes. If the desired take does not have a T-pose start/finish, then we normally load the T-pose we used during templating/setup for the shoot.

Cheers

#9

Thank you for walking me thru that, it is a little tricky, but I’ve gotten it down. I’ve also started doing a t-pose before any and all motion captures!!! That has saved me a tremendous amount of time and heartache.

Thanks again and best wishes.

Digitizer

#10

Hi there, I’ve been experiencing similar problems with my system.
I’m using measureand shapehand and suit to capture motion. Then import into MB using .c3d files.
It works fine and I am experiencing the rotated optical marker problem (Solved that out). But in addition to that, I have 19 optical markers representing each palm. On fingers and thumbs. But these markers appear to be at some distance at the back of the other markers.

To add more complications, an actor doesnt have a hand representation which i could drag drop all these markers into the correct slot. What should I do?
Also I tried to move the body markers and actors which are already in place, backwards to the palm/hand markers but it wont work. The actor seems to be pinned at that position. What should I do?

#11

Hi hajeline,

Regarding the finger mocap as markers: I don’t know. Last time we encountered this problem we ended up with a Maya rig.

As for the other issues you’re having, would you be able to attach an example file to this thread? I’m sure that will make things a bit easier.

Cheers,
Daniel

#12

Hi Daniel,

So how would I use a maya rig? Also anybody knows how to edit markers?
Or can only characters be edited and the changes are applied on the character, right?
Not the markers? I ask this because I’m doing a research and won’t be using characters.
We use MB to display point light markers from data we captured using a mocap system.
And edit these markers so that they look more real. So what way should I go about achieving this? Help me someone.

For the previous problem, I can’t attach a file. The allowed file size is too TINY!! Can I have your email address maybe?

Thanks
Hazlin

#13

We only used Maya because that’s what we used to finalize the animations anyway, but if you’re keeping things in MB for the length of your project, you would obviously choose a different path.

I don’t have much information on this subject, I’m afraid. Unless you’re using gloves, MB doesn’t seem to appreciate hand/finger mocap much.

As for your scene file, just post it on any of the online fileshare sites (like yousendit.com). I’m by no means a mastermind when it comes to MotionBuilder, so the more people with access to your problem the more likely it is to be resolved :slight_smile:

Cheers

#14

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