Hello: Not sure if this has been answered somewhere in the forum already. If so, please send me a link to the thread...greatly appreciated...

If not, is this technique possible? I'm thinking of having boxers interact with each other. Thanks!

I've just done a quick search through the forums, and I dug out this post I remember someone posting...

http://www.ipisoft.com/forum/viewtopic.php?f=2&t=5409&p=8891&hilit=dancing&sid=7a57019181d5105e152424ed49353195&sid=7a57019181d5105e152424ed49353195#p8891

..problem is it appears it's only possible to track two people with the PSEye camera setup, because you're tracking colour rather than depth channels.

They say on the post that the way to do it is to have your actors wearing two contrasting colours, and that way it's easier to distinguish between the two.

Their test resulted in this...http://www.youtube.com/watch?v=ert5CY5BA5I

Carder thank you so much for your reply!

It's possible but as with single actor captures, occlusion is the main issue to be aware of. This can get tricky if the actors have to be in close contact for long periods because the tracker can't possibly deal with what it cannot see. This is true whether you use PS3 Eye or Kinect.

Here are a few tips to make life easier in production:

If you're capturing for a game it probably makes more sense to capture individual motion clips that you can mix in engine. No need to capture multiple actors at the same time.

If the motion is for a movie, I still recommend recording individual performances because you can mix and re-time motions in many 3D programs. Of course it's extra helpful if the motions are already somewhat in sync during capture. I like to use music or other audio cues to sync multiple characters during performance.

Another useful tip: rehearse an actual multi-actor session on video prior to recording motion and use the playback of the video on set as reference for your actors during the individual performance capture. I'm doing something like this for one of my music video projects: I playback a previously recorded reference video of two musicians performing a song that my mocap actor can watch and mimic during motion capture. Because the individual character performances are done to the same video and audio, the motion is in sync when applied to multiple characters; almost no correction is needed for choreography.

It helps to know in advance how your motions will appear in film. If you storyboard the action beforehand, you can record exactly you need for the edit. This makes tracking easier since you can ignore certain errors if you know they will not be visible 'on camera'.

When storyboarding your action, keep in mind that with shorter shots it becomes much easier to combine motions for multiple characters by simply offsetting the motions. Also, with shorter cuts, you can edit around individual motions to make them look interactive and 'in sync' without actually having been recorded that way. This can be mostly done in video editing (as opposed to 3D editing.)

Hope these tips are useful.

G.

_________________
Greenlaw
Artist/Partner - Little Green Dog | My Demo Reels (2013,) (2015,) (2017,) and (2019)

Watch a one minute excerpt on Vimeo now!

Very helpful Greenlaw, thank you. Love your new Brudders film btw.

I guess it comes down to capturing actors in separate "passes" and combining them, but this seems unlikely to work with physical interactions such as hugging, shaking hands and other simple touching actions. Seems like it would work best with big gestures like dancing or boxing.

I think I'll end up just buying premade motions and converting them to Iclone.

Just curious though, since you have tons of experience in this: I saw a motion collection for Iclone of two people hugging, embracing, etc. How is this done? Through tracking points on mocap suits?

Thanks!


I don't know about the motion collection you mention but with high end marker based systems, you have a lot more tracking data available even when there is some occlusion, which make that kind of interaction more possible. Also, some high end systems do not track motions optically at all. For example, some systems may use magnetic coils to measure joint rotation and position. Other systems may use gyroscopes or mechanical joints. With these systems, occlusion should not be an issue at all. But of course, we're talking about tools that are far more expensive than iPi DMC and require a lot more expertise to operate.

Keep in mind that iPi DMC was designed to be easy to use and very affordable. It's a fairly accurate system but there are limits to what it can capture. That said, you can work around 'limits' with a little cleverness. Check out 1k0's Danse Kabyle and Making of Danse Kabyle videos on Vimeo for some fun examples--who knew iPi could capture free fall motions? :)

G.

_________________
Greenlaw
Artist/Partner - Little Green Dog | My Demo Reels (2013,) (2015,) (2017,) and (2019)

Watch a one minute excerpt on Vimeo now!

Actually that level of interaction is very doable with a little help from editing programs like Motion Builder. Naturally, how difficult this is can depend of your proficiency with Motion Builder but the quality of the actor's performance will also determine how well this works out. That's where rehearsal and acting ability comes in to play.

Some examples from 'Happy Box' might be Sergeant handling the meal box and opening it in the first two shots, and Sister raising the chainsaw and dancing with it. When these motions were captured, there were no props used--everything was pantomimed by the actor, and rehearsed several times before recording the motions. After I retargeted the motions, the hand positions in these shots were close to where they needed to be but obviously not 'locked' to the objects the actor was pretending to handle during performance capture. Not a big problem for MB though--using its pre-built IK system and Auxiliary effectors, it was fairly simple to correct these 'errors'.

Granted, these are not examples of direct contact between two characters but they do illustrate how you can achieve precise contact of two hands with other objects in a scene--it's not a big leap to go from that to precisely 'touching' another character.

BTW, I only mention MB as an example because it's what I used for 'Happy Box'. IMO, you can do similar editing tricks in other mocap editing programs like Webanimate or Jimmy|Rig Pro and, depending on your rigging/animation skills, in some general purpose 3D programs like Maya, Blender or Lightwave.

G.

_________________
Greenlaw
Artist/Partner - Little Green Dog | My Demo Reels (2013,) (2015,) (2017,) and (2019)

Watch a one minute excerpt on Vimeo now!