View Full Version : actor fit from vicon data

09 September 2006, 07:31 PM
I have a small question for a project that I'm working on. I got some pretty clean data from a vi con system and the kinamatic fit is pretty much perfect with no kind of flipping or anything. When I go to put the data into motion builder the data looks fine untile I fit the actors onto the data. There are two characters in the scene. One has a flipping elbow for about a third of the scene in the middle and then it goes back to normal. Both actor's have there hands flipped around for at least half of the scene and then for other parts seems to be ok but not great. I've been fitting the actor's pretty close to the sensors from the data so I'm not sure why it's doing this and just wondering if there's something I'm doing wrong or if there's something else I can do to get it a little cleaner before I try to send it over to a character. Any help would be really great and appreciated. Thanks a bunch!

09 September 2006, 08:19 PM
i can't help much but point out 2 or 3 things.

1) motiondata may seem clean until mapped to a actor or another character, thats the moment all the messy details like to show up.

2) maby you are already aware of ,but in motionbuilder you have Tons of setup_menus for cleaning, constraining, dampening, offsetting, footstep_behavior and much more for the actor
with some experimenting you can tweak a lot of problems there.

3) f-curves and keyframes: you can clean your raw data using fcurves and/or using keyframe for some minor fixes after plottet to the rig , try using unroll in the plott settings

09 September 2006, 07:01 AM
ok thanks, that helps and I'm going to try out some of those things. I have definatly noticed that things look a lot different when their fit to an actor in motion builder. I'm just starting to use motion builder so it'll take a little bit. Should I try to clean the data when it's still on the actor or should I transfer to a character and clean it up on the characters? Anything that you can sugest would be of help since I'm just getting into using motion builder and mocap. Thanks a bunch

09 September 2006, 01:22 PM
depends on what you have to fix.

to use any keyframing for cleaning be sure to plott the motion data on a rig first.
for f-curve cleaning i use the skeleton without any rig.

but as i have only deeper experience with having bvh files as raw data things may be different using vicon marker data.

i use f-curve cleaning process on the raw data for major fixes like body_sliding,flipping and jitter as say can be spotted very easily with in f-curves.

i use the rig for cleaning sliding foodsteps, bodyposes, and arm's intersecting the torso and so on.

just start experimenting with all the options you have,give yourself enough time, be ready to do "try and error" and things will come along

09 September 2006, 08:59 AM is often a good idea (if you can) to go back to the raw data and check that your optical marker set up/labelling is correct in the first place. Its easy to miss marker switching in wrists etc before you map it onto your actor in MB. Vicon IQ is perfect for this as its post-processing allows you to 'hopefully' iron out these problems either manually or through its automated pipelines. This saves hassles further down the line. In saying that....MB is pretty good for basic filtering and re-labelling if need be.

09 September 2006, 05:44 PM
Thanks for the info. Just another question. Should I really try to do the clean up in vicon first before I try to do it in motion builder? I've been trying to figure out how to do it in motion builder but haven't been having a lot of luck with it. I don't seem to be able to find any tutorials on how to clean up mo cap data in motion builder. Will it clean faster in vi con or is it easier to do in vicon. Just starting to use the mocap and the mocap lab is fairly new at the school so I'm kind of pioneering the mocap and I'm not really able to get a lot of help from teachers since they are learning this as well and are about in the same area as I'm in. Any help/ advise would be great and is really needed. Anything anyone can tell me would be wonderful. Thanks again for the help so far.

12 December 2006, 02:53 AM
I know this is a late follow up but, I got flipping hands using the bvh format out of Motion Analysis going into Max. The data in MA was clean and oriented correctly. I think this is a byproduct of the bvh format.

12 December 2006, 11:22 AM
Hello, skater,

If you have IQ program (Vicon), it is really a good idea to fix everything in mocap data, which can be fixed, in IQ first. That incdudes flipping limbs (head, hands often flip), jittering (this happens often if you have a few cameras) etc. Then data is usually filtered to get smooth curves.
Then the mocap data, cleaned in IQ, is transfered to MB (export to FBX file option). Then you put it to an actor (I usually do not clean it at that stage).
Afterwards you put the motion to your Character, plot it to Skeleton, then to Control Rig and edit it. Try editing That includes correcting overlapping limbs, intersections of hands, legs with body and other items attached. If you have still some minor jittering or flippings (missed at the stage of IQ cleaning)- that could be corrected using F-Curves and Keyframing.
Hope, that helps.

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