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 Post subject: Getting Closer!
PostPosted: Thu Jul 01, 2010 9:20 am 

Joined: Thu Jun 10, 2010 3:04 pm
Posts: 13
Here is a link to my most recent test.

http://www.vimeo.com/13008070

Password: ipi

I probably tried about ten different set ups before reaching a decent output. I used four cameras in my garage, 640x480 at 50fps. Gray concrete floor with white walls. I wore a black t-shirt with a long sleeved red top underneath. Dark brown cords with black shoes and also tried white shoes. Which leads me to my question. Any ideas on how to improve the foot tracking?. They are sliding all over the place. I know I can do it in post with a script in Poser etc but I would like to fix it at the tracking stage, if possible.

I am working in 3DS Max by the way.

Let me know your thoughts.


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 Post subject: Re: Getting Closer!
PostPosted: Thu Jul 01, 2010 1:47 pm 

Joined: Mon Aug 03, 2009 1:34 pm
Posts: 2346
Location: Los Angeles
Pretty nice!

It's a little hard to tell how much the feet are sliding because of the flat gray floor texture and the compression of the video. Could you put a small grid or checkerboard pattern on the ground?

BTW, what are your camera positions? It's currently recommended that they be arranged in a semi-circle.

My first iPi DMC-PS3 Cam tests looked surprisingly good but I haven't checked the mocap data in a 3D app yet. Let you know if I run into any slipping issues when I do (maybe today) and if I find a solution.

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Artist/Partner - Little Green Dog | Demo Reel (2017) | Demo Reel (2015) | Demo Reel (2013)

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Watch a one minute excerpt on Vimeo now!


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 Post subject: Re: Getting Closer!
PostPosted: Thu Jul 01, 2010 2:34 pm 

Joined: Thu Jun 10, 2010 3:04 pm
Posts: 13
I can definitely put a version with a checkerboard pattern. There is a prime part of the animation which shows the feet sliding. If you look at the feet when I am doing the swimming motion (Front crawl), they are supposed to be firmly planted with no movement but as you can see they are all over the place.
I arranged four cameras in a semi circle. Another thing I noticed is the motion seems very tame compared to the actual movements I recorded. I plan on the next try to exaggerate movements to compensate for this.

Definitely let me know if you have any slipping issues.


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 Post subject: Re: Getting Closer!
PostPosted: Thu Jul 01, 2010 5:32 pm 
iPi Soft

Joined: Tue Mar 31, 2009 9:13 pm
Posts: 804
Thanks for sharing this video, it is very interesting.

Enlighten wrote:
Any ideas on how to improve the foot tracking?. They are sliding all over the place. I know I can do it in post with a script in Poser etc but I would like to fix it at the tracking stage, if possible.


This particular foot motion is pretty difficult to track. You stand on the floor and twist sideways with torso and hips while having feet planted firmly on the ground. In real world, this involves a combination of twist of upper and lower legs and even some foot sliding inside the shoes. Current version of the system just doesn't have enough degrees of freedom in skeleton to track such complex motion. This will improve in future versions but it will take us some time to implement (probably several months). Adding degrees of freedom involves a huge amount of testing in order to ensure that we do not break tracking of other motions.


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 Post subject: Re: Getting Closer!
PostPosted: Fri Jul 02, 2010 3:29 pm 

Joined: Thu Jun 10, 2010 3:04 pm
Posts: 13
Thank you so much for the clarification. Do you know how to fix the foot sliding in 3DS Max?. I tried Poser with the BVH foot sliding script but that didn't work. I also tried to fix it in Motionbuilder with no success.


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 Post subject: Re: Getting Closer!
PostPosted: Sat Jul 03, 2010 4:27 pm 
iPi Soft

Joined: Tue Mar 31, 2009 9:13 pm
Posts: 804
Enlighten wrote:
Thank you so much for the clarification. Do you know how to fix the foot sliding in 3DS Max?. I tried Poser with the BVH foot sliding script but that didn't work. I also tried to fix it in Motionbuilder with no success.


You can try Endorphin: http://www.naturalmotion.com/endorphin.htm
It is expensive but it has really working physics-based foot skate removal technology.

Poser and MotionBuilder are based on outdated technologies and are not very good at removing foot skate.

Generally speaking, your motion is very complex and it may be hard to eliminate all foot skate in this animation without implementing a biometrically-correct skeleton inside the capture application (as I already mentioned, this will take us some time). Simple methods will not work. Without seeing original video, it is hard to tell if there was foot skate at all or if the actor was intentionally rolling on heels.

The animation does not actually look that bad in its current form. Maybe you can just pretend that actor was actually rolling on heels in this animation?


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 Post subject: Re: Getting Closer!
PostPosted: Mon Dec 06, 2010 5:31 pm 

Joined: Thu Apr 09, 2009 3:12 pm
Posts: 16
Firstly great software IPISOFT! I work with inertial systems (Animazoo) and its great you are giving people the chance to experiment with mocap on a shoestring..:))

Just thought I would add that I think Motionbuilder is actually very good for editing mocap data, if you characterize the rig and then plot the data to an IK/FK control rig you can access the IK positional data for the feet end effectors and simply flatten the keys on X,Y,Z where they are sliding... you can also adjust the hip to compensate for any IK knee popping.. Also you can apply a wide range of filters to the data and then just plot it all back to the skeleton as FK data.. also I found that adjusting the actor height to adjust the softwares IK reaction to the tracked data drastically affects the quality of the data. If the virtual actor is too tall compared to the real one, you will see the lower leg over rotating when the knees are bent, when too short they dont bend enough.. Also I wear some white socks on my hands and that really improved the hand tracking..

Hope that helps..


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 Post subject: Re: Getting Closer!
PostPosted: Tue Dec 07, 2010 4:48 am 

Joined: Wed Aug 04, 2010 10:16 pm
Posts: 23
Hello,
With your type of motion (twist with the legs remaining stationary) its not technically the "foot sliding" effect. The foot sliding effect occurs when the target 3d figure is not scaled exactly as the target figure used to create the bvh file. Even if you use the exact figure this scaling issue sometimes occurs in BVH files. Just look at the early version of IPISOFT. The sliding is done across the entire body....not just the feet. The entire figure is sliding across the floor or whatever. That's why you haven't had much success correcting the issue in Poser (if you tried BVH Constraint). Most scripts that deal with foot sliding will try to eliminate the scaling issue by offsetting the overall animation from the point of origin. In your case your feet aren't sliding so much as the software thinks your feet are moving in that manner. Your feet are being pulled by the arms (because of the lack of range of motion). You need to try a different approach. Motion builder and Poser can definitely fix your issue. In Poser I would just eliminate the frames of animation of the rotation of the legs while twisting. In motion builder I would just add constraints to the feet which would keep them in place for the duration of the frame range you choose. I can't imagine MB being called outdated. There isn't another animation tool on the planet that can do as much as it does. Good luck.
Andre O'Brien


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