maybe you already thought about it, but who knows, maybe im a genius :D


well, i have had a really bad time correcting the feet in max. ipi exports them just as 90° from the leg and that's all. it does so much jittering and vibration that most of the time i have to completely kill the legs and redo them by hand.
i can understand that the kinect doesnt give enough information to track the feet correctly and ipi can't do better right now.

we know where the ground is. we know that feet like to be on the ground, supporting the body weight, and because of that, it doesnt move much.
so, in the end, the feet arent really free to slide or move anywhere.
ipi should give a first try at locking the foot on the ground, then rotating the rest of the leg to join the pelvis. (ik style)
if the leg pass above a treshold, ipi would consider moving the foot. that treshold would be customizable.

that feature would work too on the hands in case of acting a mime or so. if the treshold would be 0 then the limbs would be free to move without this constraint.

I think your off base.

Feet not working? Jittering, Sliding??

WHat in blazes are you talking about?

I think maybee you have iPi confused with some other program

Cheers

I know what you mean l2k. Foot tracking does sometimes have issues like that. I've tried a few different things to clean it up.

First, apply some smoothing and jitter removal inside iPi. This often does a fair job of cleaning it up.

In Blender I've tried killing all the foot rotations and adding some constraints to the foot bones. Like a floor constraint to keep them from going through the floor and an IK constraint and location constraint to a manually positioned and keyframed empty. Sometimes this works really well, sometimes not so much, it depends on the motion.

I've also tried JimmyRig's Grounded and Anti-Skate modifiers. These usually work pretty well, and only a little bit of manual modification is needed, if any.

I believe Motion Builder also has some pretty good tools in this department if you don't mind shelling out the cash for it, but I do, so not very familiar with it.

Adding grounding and anti-skate code to iPi would be great. Especially if you could toggle it on and off during tracking.

+1

what i mean is while ipi does a pretty good job with body and arms, the feets are not that great.

and i can smooth or jitter remove as much as i want, the sliding and jittering stays, wich is annoying me very much, hence my proposal of including a kind of solid lock

Dont confuse this issue.

iPi is not creating any foot jitter.

I have found that on some rigs it appears that the foot jitters like an electric toothbrush, but that is fault of the rigg, not iPi.

I like the feet tracking in iPi as is.

Thanks

Cheers

Just curious but are you using single Kinect or one of the more advanced setups? Single Kinect is less accurate so you may see more jitter and/or sliding than in the results from more advanced setups. That said, if you use more aggressive Configurable Jitter Removal (CJR) on the legs than other body parts, you should see a great reduction in jitter. Too much CJR, however, may make the motions too smooth and robotic, so you probably don't want to set it to max. (Or maybe you do...I'll leave that up to you.) :)

With Kinect results, single or dual, I do see a little more jitter than with PS3 Eye. You can see this in Happy Box in a few shots. Generally, it's more noticeable when we get very close the characters and when they are sitting very 'still'. I find that when the character and camera is moving the jitter is not very noticeable though.

Excessive feet sliding is not normal with DMC. I've been using DMC for a few years, and most of the time DMC has done a remarkable job keeping feet locked to the ground plane. Where I do encounter sliding is when when the performer has certain degree of twisting in the hips and DMC can't roll the thighs or rotate the heading of the ankles enough to correct for this. My understanding is that if iPi relaxed the limits it may lead to more serious tracking issues, so you just have to accept this. Luckily, the problem is rarely noticeable and should be easily correctable in a 3D app though.

Here's an example of the type of sliding I'm talking about:

iPi Studio Markerless Motion Capture: Deform Test Mocap

You can see the feet are more or less locked to the ground except for the few seconds starting at 20s where the performer twists in place. Elsewhere, you should see very little sliding even when the actor walks in a tight circle. Granted this test was done using the four PS3 Eye setup but DMC's rules for good tracking are generally the same even with single Kinect data. (Well, except for the walking in a circle part of course, which would be a bit much to ask from single Kinect tracking.)

Now, if you are talking about a problem with constant sliding even when a character is standing still, then something might be wrong with your data. The issue can be caused by loading poor or incorrect calibration data or using an improperly scaled actor for tracking.

I'll assume you have Feet Tracking is enabled, which you need especially if a character is standing and walking. FYI, I sometimes need to disable Feet Tracking but this is when I'm trying to resolve another issue and if I don't need the feet to be locked to the ground. (For example, one or two shots in Happy Box have Feet Tracking disabled but you do not see the feet in those shots anyway.) Normally, it should be enabled if you want the feet to be locked to the ground.

Hope this helps.

G.

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

Watch a one minute excerpt on Vimeo now!

this is after a lot of smoothing and jitter removing.

notice how the feet are sliding and jittering.

http://youtu.be/BDe4ovgg0X4[/quote]


my character is giving a presentation, turning big papersheets over a board.
he is more or less static. he doesnt runaround or do pushups.


if something is wrong with my calibration, ipi isnt doing his job well, cause its suposed to be automatic with the kinect.



and unfortunately, my 3d ap is max, and i'm to use the biped. not my choise. and biped doesnt let me correct that easily. (he's a pain in the ass too)

Thanks for posting that video...it's more useful to actually see what we're trying to troubleshoot here. :)

Part of the problem I see is exactly what I described in my post, where a certain degree of hip twisting can cause the feet to twist undesireably in rotation. You can fix this in some 3D programs by constraining the rotation to a target. I don't use Max, but I imagine you should be able to do it there. In some simple cases you might get away with removing some keys in the appropriate rotation channel but this really depends on the motion and may become 'tweaking hell' in some situations.

Alternatively, you could reshoot your performance to minimize this twisting motion. Because reshooting with Kinect is fast and simple, I personally would rather do a reshoot and then correct any ankle twists that might still be present.

Tip: For obvious reasons, a single Kinect sensor cannot solve occlusion issues. I would suggest you perform more towards the camera instead of away from it. For example, the rig goes crazy at certain points in your video because iPi cannot see what your 'rear side' arms and legs are doing at these points. If you walk towards the camera closer to a 45 degree angle, it may see more of what's going on with your right arm and leg. The thing to remember when performing (for any configuration) is that more of you iPi Studio can see, the more accurately it can track you.

Adding a second Kinect should prevent most of the 'spazzing' problems but even with additional cameras you still need to be aware of what's being recorded and how it will be interpreted by Studio to get predictable results. If I'm about to do a motion that I'm not sure will track properly, I will rehearse and try variations that I think might work better. Studio let's you define takes, so you can output only the motion that works best for your and discard the rest.

Since your using Biped in Max, am I correct in thinking you have the ability to mix motions? If you're restricted to capturing with a single Kinect, try creating two motion clips, one with your actor walking towards the camera and a second motion with the 'presentation' gestures. Working with two clean well-behaved motion clips instead of one long 'problem' clip may work better for solving occlusion issues.

As for the big 'pops' that occur in the torso and legs, I think you need to adjust the height of your rig. To me it looks like the actor is not fitting the volume space optimally and the collision system is playing havoc with the rig's IK system. Try scaling the rig up or down in Studio and refitting where necessary. iPi recommends that the actor be a little taller than normal but sometimes I find shorter works better. This might be because of my physical frame (I think my legs are a little shorter and my torso is slightly longer than average.) Experiment and see what works best for your frame.

Also, if you use varying levels of CJR or if you use CJR for limited ranges of your take, you need to 'bump' your Trajectory Filtering to 0 and then back to your preferred setting after you run CJRl. This smooths the transition in the motion curves between different levels of CJR.

BTW, if you use CJR, it is applied to a layer above the original track data, so you can edit and redo CJR without worrying about altering your carefully tracked motion data. Of course, you should be satisfied with your track before moving onto the jitter removal stage because no matter how high you set CJR, it cannot correct bad tracking errors. I suggest reshooting the motion to minimize the problems and learn how to fix the tracking errors first before worrying about jitter.

Hope this helps.

G.

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

Watch a one minute excerpt on Vimeo now!

Thanks Greenlaw, that was very helpful. I appreciate the time and thought that went into the post, it was very well explained and I'm sure will save me some time in the future.