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simsimma31
03-16-2010, 09:39 PM
Hi, I have been scratching my head for days trying to figure out how to get a better arm deformation. As you can see from the image when I bend my character arm I get a U-shape which is very unrealistic for a human subject. I have tried to cure the problem using weightmaps and still no joy, may-be I am not doing this right?

Please is any one able to rescue me :help:

Regards

SplineGod
03-16-2010, 11:29 PM
Can you post a screengrab with the bones showing?
You can mess with:
bone placement
bone falloff
bone strength
adding in extra bones

hrgiger
03-17-2010, 04:12 AM
The best default position for your arms will be at a 45 degree angle from body. So not resting at the sides and not straight out from the character, about half way between. Also as Larry mentioned, bone (joint) placement is key. You want and try to position the joint of the upper arm/shoulder right where the socket would be on an actual person.

RebelHill
03-17-2010, 06:07 AM
The only way to get good shoulders in LW is with a 2 bone joint solution... U can weight, and morf and hold bone for all ur worth, but U'll only get it to work right for 1 or 2 directions.

Check the top link in my sig, and watch the secind half of the vid for perfect deforms.

simsimma31
03-17-2010, 06:16 AM
Hi,

Here is the screen grabs, I am using a Maestro Motion Builder Rig for animation purposes.

@ hrgiger I have tried to angle the arms at 45 degree angle as seen in the image when the arm is raised-up looks horrible @ the shoulders. I could however create a script for the shoulder bone to rotate to the correct position when the arm is rotating up (light bulb moment) as mentioned I am using Maestro to rig so not sure how I would do this with my limited knowledege.

Regards

simsimma31
03-17-2010, 06:29 AM
The only way to get good shoulders in LW is with a 2 bone joint solution... U can weight, and morf and hold bone for all ur worth, but U'll only get it to work right for 1 or 2 directions.

Check the top link in my sig, and watch the secind half of the vid for perfect deforms.

Hi RebelHill,

I have purchased and watched your video tutorial, but for some strange reason it's not sinking in. I am slow that way ;D Maybe I should go back and spend time watching it again. I am working to a tight deadline to get my characters animated hence the reason I purchased Maestro.

UnCommonGrafx
03-17-2010, 07:21 AM
Pick some of the bones around the areas that aren't deforming, pull the tips of the bones coming off the upper spine bones or a combo of the two.

With a maestro rig, there's no problem adding bones and the like to assist in controlling deformation.
Add some bones in that area to test. All of the other suggestions will work with a maestro rig. If the bones don't work, delete and try again. What you want to do is possible with that rig.

RebelHill
03-17-2010, 08:26 AM
I have purchased and watched your video tutorial, but for some strange reason it's not sinking in.

Well, there is a lot there... I suggest focussing in on the relevent parts to you.

Whilst the maestro rig does pretty well, and gives good deforms, its still not the best for shoulders...

My own stuff shows 2 different parts... theres control rigging, and deform rigging (skinning)... and you can happily apply the skinning method to any control rig, maestro, collada, fbx...

I recommend you review vids 5a, 5b to get urself down on the differences between using Zbones and Joints...

Then go through 20a to get the basic idea behind targeting a deform rig onto a control rig, followed by 20d for specifics on shoulder deformation.

You should also check out later the rhrud1, update videos, which will show u how to take the rigs supplied with the tutorials and bolt them into different character meshes, saving you the effort of building the whole thing from scratch.

Best.

simsimma31
03-17-2010, 09:31 AM
Well, there is a lot there... I suggest focussing in on the relevent parts to you.

Whilst the maestro rig does pretty well, and gives good deforms, its still not the best for shoulders...

My own stuff shows 2 different parts... theres control rigging, and deform rigging (skinning)... and you can happily apply the skinning method to any control rig, maestro, collada, fbx...

I recommend you review vids 5a, 5b to get urself down on the differences between using Zbones and Joints...

Then go through 20a to get the basic idea behind targeting a deform rig onto a control rig, followed by 20d for specifics on shoulder deformation.

You should also check out later the rhrud1, update videos, which will show u how to take the rigs supplied with the tutorials and bolt them into different character meshes, saving you the effort of building the whole thing from scratch.

Best.

Thanks, I think I am gonna have to go get a cup of coffee..roll my sleeves up and follow your tut again..cose at the moment I am going around in circles and lossing lots of sleep.... Just a few questions.

1) Is it really relevant to have my arm @ 45 degrees?
2) would I be able to use the rig with motionbuilder?

Many thanks

RebelHill
03-17-2010, 10:32 AM
the arm at 45 deg is helpful, but not essential... Its the mid point between the extreme up for the arm (which is Tpose) and the down pose.

If you have a MB skeletal control rig that lets u get motions from MB to LW... then the deform rig is of no consequence one way or the other, as it targets the result of that control rig, you just wouldnt send the deform rig to MB as it wouldnt do anything, except cause problems most likely.

ericsmith
03-17-2010, 11:20 AM
The main thing I'm seeing from your screenshots is that the clavicle and shoulder bones should follow the contour of the top of the shoulder more. I've attached an image of how I place them.

RebelHill - I won't claim that my shoulder setup is perfect, but I have put some significant R&D into a solution that works pretty well for a wide variety of characters. I'm interested to see how you approach this tricky area and am now downloading the free 3 hours from your site (although I'm not sure if this topic is included in that). At any rate, further discussion on different ways of approaching shoulder deformation would be very worthwile, in my opinion.

Eric

RebelHill
03-17-2010, 11:57 AM
no, its not included in that set... but as for how to... Its just a good old fashioned 2 bone bridge. 2 joints targeting across a single joint control, with pole-ing to prevent twists and flips.

ericsmith
03-17-2010, 12:20 PM
Yeah, I use two bones as well, just like in the knees.

The tricky thing is getting the flesh in the armpit area to compress and drop down when the arm comes down, and not twist very much at all when the arm twists to lift the hand over the head.

Anyways, I'm always on the lookout for other ways of approaching it.

Eric

RebelHill
03-17-2010, 12:52 PM
Sure thing...

Thig is that you rig, being both deform and control rig prohibits you from being able to use the child<>parent deofrm compensation options, as you've got lil nested sections of hierarchy.

The underarm hold structure I always tie into the clavicle, pointing it at an angle thats an intermediate of the angle between the clavicle and the spine... I do it now with null and same as item... but previously Ive used expressions.

The other issue I have with using the combined deform/control setup is that when you use the 2 bone solution, it means you've got 2 bones to deal with when animating in FK mode, which is just a nightmare when it comes to doing fcurve work, etc.

Dont get me wrong, I wasnt meaning to impune upon ur rig at all... its about as good as it could get with ol school LW, and certainly about as good as u can get using a deform/control rig all in one.

Check out this quick lil example Ive knocked out... by separating out the deform and control sections of the rig, you can get much mroe control over deforms with far fewer bones for hold structure.

RebelHill
03-17-2010, 02:07 PM
I am the farthest thing from an expert here, but can't Joint Compensation also help in this case?

Only in a direct bone to bone hierarchy... because it works parent to child, it cant bridge the gap between inbetween bones that handle gimbal, hold structures, etc.

SplineGod
03-17-2010, 03:30 PM
Joint compensation could help.
Also keep in mind that bones used to deform such as special bones in certain regions can be moved, sized, stretched, rotated etc as need to get the proper deformations. Those channels can be tied to the behavior of other bone channels to automate using cycler, cyclist, channel follower, targetting, expressions etc etc.
That can also be combined with morphs and/or any other way of acheiving deformations. :)