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 Post subject: footsteps drift jitter
PostPosted: Fri Apr 26, 2013 2:22 am 

Joined: Wed Mar 20, 2013 11:47 pm
Posts: 5
Hi
I've been used the software movimento and my camera is six 120fps high speed camera, but it is inefficient, the manual operation is relatively complicated. So I choose ipisoft2.0 recently, the camera is 2 kinect, I found the problem:
1 ipisoft can not track the rotation of the arm accurately.
2 the footsteps drift jitter, although i can use the smooth filter.

I want to know:
In the footsteps of drift jitter issues, six pseye is better than 2 kinect?
(sorry for my poor english)


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PostPosted: Fri Apr 26, 2013 7:55 am 
iPi Soft

Joined: Wed Jan 11, 2012 6:12 am
Posts: 2355
Location: Moscow, Russia
Hi
PS Eyes are better in overall feet tracking than Kinects. Kinect's depth data does not have enough resolution for good feet tracking.
As for the arm rotation, can you please provide an example of such problem? Screenshots, project/video files?


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PostPosted: Fri Apr 26, 2013 1:56 pm 

Joined: Mon Aug 03, 2009 1:34 pm
Posts: 2423
Location: Los Angeles
I solve foot jitter by increasing CJR for the legs when the character is standing in place, and then reducing it a little when the character is walking. In general, it should be higher for the legs when standing or walking.

If you're using a single Kinect, the feet may drift backwards when crouching or squatting. This is because the volume has no 'backside' and collision with the ground may force it backwards through the opening. This kind of error should be easy enough to fix in the animation program you export to.

With 2 Kinects, feet stability is better but the same error can occur when using the 90 degree setup. When using four to six PS3 Eye cameras, there is less chance of feet jittering away because there is more coverage. That said, I get reasonably stable results even when using 2 Kinect at 90 degrees.

If I still have trouble, I’lI turn to the pinning tools in Motion Builder to lock feet in place.

Here’s an example:

http://www.youtube.com/watch?v=jASC8IOsIqY

If you watch the video in stage 1, you can see the feet drift backwards when ‘Sister’ jumps forward. I tried to stabilize this as best as I could in iPi Mocap Studio but in the end I had to pin and release the feet in Motion Builder at the beginning of each jump. For the rest of the motion data, high CJR for standing still and medium CJR for walking was quite adequate.

If you’re expecting the feet to be perfectly locked and stable all the time, it's very likely that you will need to edit with another application that has pinning. (Like MB.) My hope is that iPi Mocap Studio will get this feature in the future.

G.

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PostPosted: Sat Apr 27, 2013 8:19 am 

Joined: Wed Mar 20, 2013 11:47 pm
Posts: 5
Thank you, Greenlaw. As to the capture rotation of the arm, I guess it is caused due to the depth camera resolution, so the 3d model data is not so meticulous to measured the slight rotate, I will upload the project file later.

I have another question, can i use 6 pseyes in the outdoor work platform, where there is enough space, I use movimento outdoors because it is not based on IR, only videos, is pseye the same principle? I know kinect can not calibrate in the case of direct sunlight.


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PostPosted: Sat Apr 27, 2013 9:36 am 

Joined: Mon Aug 03, 2009 1:34 pm
Posts: 2423
Location: Los Angeles
Occasionally, I get bad rotation in the shoulder when tracking forward. This problem is usually easy to correct--go to a later frame, correct the rotation and click Refit Pose, and then track backwards through the error.

In difficult cases, you many need to step through and do this manually (adjust, Refit, step back, adjust, Refit, step back, etc.) for a few frames. If it's really difficult, you many need to step through the entire error like this. This is still pretty easy to do though.

After the error has been corrected, you can return to the last frame that was successfully tracked and proceed forward.

G.

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PostPosted: Sat Apr 27, 2013 9:41 am 

Joined: Mon Aug 03, 2009 1:34 pm
Posts: 2423
Location: Los Angeles
I haven't used PS3 Eye outdoors but many users have done this successfully. The key is to avoid direct sunlight--harsh shadows will make it difficult to calibrate and track the data. The ideal time is early in the morning before the sun is up, or on overcast days when shadows are very soft and the lighting is ambient.

A Maglite in candle mode probably will not work well for tracking outdoors in a large area so you will need to use an alternative device. Some users like using a white or mirror ball on a stick. This can be an over-sized tree ornament or a styrofoam ball from a craft store.

Hope this helps.

G.

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PostPosted: Sun Apr 28, 2013 6:51 am 

Joined: Wed Mar 20, 2013 11:47 pm
Posts: 5
The x-axis (red) rotation can not be tracked by the record video


Attachments:
ipi.jpg
ipi.jpg [ 82.43 KiB | Viewed 45901 times ]
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PostPosted: Sun Apr 28, 2013 9:25 am 

Joined: Mon Aug 03, 2009 1:34 pm
Posts: 2423
Location: Los Angeles
The red rotation shouldn't rotate very much since it's basically the 'roll' for the forearm. If it's not rotating enough for your capture, you may need to adjust the shoulder, as described above, and retrack through the error.

If the issue is that the elbow won't bend in the direction you want, that's definitely a shoulder issue--make the adjustment upstream and retrack.

If the issue is palm orientation, that's mainly adjusted downstream at the wrist not elbow.

G.

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PostPosted: Wed May 01, 2013 6:54 am 
iPi Soft

Joined: Wed Jan 11, 2012 6:12 am
Posts: 2355
Location: Moscow, Russia
LittleGao wrote:
The x-axis (red) rotation can not be tracked by the record video

This exact rotation (roll of lower arm) cannot be tracked by optical or depth sensors, because arm's image is very similar in different roll angles. Especially when it's covered by sleeve (usual case).
What we can do is to track wrist orientation (affected by lower arm's roll) with motion controller. Though we apply captured roll orientation to the wrist bone itself rather than to lower arm bone. This is not correct from the view of human's anatomy, but is more convenient for application to 3D models to avoid skin distortion of a model.


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PostPosted: Sun Jun 09, 2013 3:55 pm 

Joined: Wed Jun 05, 2013 4:46 am
Posts: 36
oh~~~~I found that you can track the finger movement,6EYE Can do it?

http://www.youtube.com/watch?v=jASC8IOsIqY


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