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shalabology
11-02-2008, 10:49 PM
although the introduction of skin morph in addition to the robust skinning tools i still find difficulity to get the hip skinned as perfect as i imagine .
for example if i took care about one leg positions around the pelvic joint doing morphs for each pose , if i passed this i find that if the character bends i get weird deformations in the pelvic area even they r well skinned before skin morph , and no wonder in this coz the same verts are the participants in creating morphs , so i end up by fixing not many poses as i wish to get the most compromising skinning for that area.
i always wanted to skin a character that acts like a gymnast and gymnast animation includes very extreme positions in the hip area like splits and also includes many tucks that requires the spine to be bent over the pelvic .
so any ideas or suggestions?

archanex
11-03-2008, 04:07 AM
My suggestion is to not use skin morphs for the hip =)

Frankly I'm not a fan of skin morphs in general (I prefer regular morph targets), but you can get away with them on areas that only bend in one axis (like the knee or the elbow)

shalabology
11-03-2008, 05:00 AM
Thats Good But What Do I Do For The Pelvic Area To Get The Perfect Look For Active Full Range Moving Limb Of The Gymnast Character As I Mentioned Earlier?

archanex
11-03-2008, 06:22 AM
I'd recommend buying some DVDs

if you're using Max, Paul Neale has an excellent series on rigging

if you're using Maya, I'd recommend Fahrenheit Digital, I've also heard good things about Jason Schliefers series as well

shalabology
11-05-2008, 03:45 AM
you know what archanex: you have inspired me with the idea of using just ordinary morphs for that area , i will try to make them be driven by angle changes that will be read by xpose transforms , as soon as i finish the rigging of the current character i will try this , but still aspiring for any approved methods , anyone have brilliant ideas here?

Coyote12
11-05-2008, 11:32 PM
I would suggest using a corrective blendshape to fix the hips and crotch area deformations for when the legs go to that extreme. I usually have to do that all the time since weighting can only fix so much and the crotch can bend in some odd deformations when the thigh gets near 90 degrees or more. Then just connect the blendshape to be set driven keyed to the angle of the thigh.

tonytouch
11-06-2008, 09:06 AM
i guess the best way , to achieve accurate deformation on the hips , is to use 3 different correction-shapes : one for the left hip , one for the right hip , then finally one third ontop , that is additionally driven-in when both legs are being raised ( lets call it the "correction-shape for both corrections" ... as these 2 hip-shapes will "add" and especially in the middle-area of your mesh , will lead to double-transformations - with this third shape you can correct this issue then ... finally you can automate the weight for this 3rd morph ( 3rdMorph.weight = rightHip.weight * leftHip.weight ) .

if you are setting up realtime-characters ( without morph/blend-shapes ) you need to add additional bones.

DracoDralion
11-06-2008, 09:20 AM
i guess the best way , to achieve accurate deformation on the hips , is to use 3 different correction-shapes : one for the left hip , one for the right hip , then finally one third ontop , that is additionally driven-in when both legs are being raised ( lets call it the "correction-shape for both corrections" ... as these 2 hip-shapes will "add" and especially in the middle-area of your mesh , will lead to double-transformations - with this third shape you can correct this issue then ... finally you can automate the weight for this 3rd morph ( 3rdMorph.weight = rightHip.weight * leftHip.weight ) .

if you are setting up realtime-characters ( without morph/blend-shapes ) you need to add additional bones.

This sound interesting, but I can't really get the whole thing visually. Could you draw a quick sketch or something showing how it would work?

timothyc
11-06-2008, 09:47 AM
You've basically got two strategies to choose from:

1) blendshape (a.k.a. morph) corrections.

2) muscle/skin simulation.

The trouble with going for the muscle/skin sim is that if you want realism you're going to have to add some morph corrections on top anyway, in order to tweak the extreme poses. Or else be prepared for an incredible workload getting the myriad of muscles to interact not only with each other (i.e. as softbody collisions) but also with the underlying bones and tendons. And realise that muscles don't just generically bulge out when they contract, each one deforms in a precise way as it squashes and stretches.

Another consideration is whether you consider yourself more a rigging "engineer" or rigging "artist". An engineer would be more likely to go the sim route, but since I'm more "artist" I'm more confident I can identify the anatomical flaws that make a deforming joint "not look right", and then proceed to resculpt it with a new morph, than I am in my technical ability to program a solution.

So for this http://www.youtube.com/watch?v=2gkLRhSdZJ0 I went for morph corrections.

My best advice is to devise an orderly arrangement of poses for testing the blendshapes. Don't just leap in and start sculpting corrections higgledy piggledy. Create an animation of the hip joint going through its full range of motion, break it down into a set of regular angles (say, every 45 deg), and then work your way through the animation, sculpting the corrections as you go. Be prepared for alot of work, because there'll be plenty of back and forth testing of each new blendshape with the effect it has on the other ones it overlaps with. IOW, the combinations and permutations of the morphs having their effects added together will start to build up and threaten your sanity if you don't approach the problem in a thoroughly systematic way.

TC

EDIT: you can download the animation mentioned above from here:

http://rapidshare.de/files/40852580/floorRoutine.mpg.html (http://rapidshare.de/files/40852580/floorRoutine.mpg.html)

tonytouch
11-06-2008, 10:51 AM
wow TIM .. this looks great !!!

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ok , for the theory ... i was writing about - here some more info:

you got 2 blendshapes ( morphs ) that "add-up" ( like in picture 1 )

but the final result shall look like in picture 2

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therefore you need to create a third morph / blendshape

e.g. for the hips , you could connect each X-rotation of each leg-bone into the weight for each of the corrections ... then - to have the 3rd shape being driven automatically , just multiply both-weights and connect the multiplication into the weight for the 3rd shape - so it will be automatically , when both legs are up ( this way , the pelvis-area of the lower lumbar-spine will deform more predictable and accurate .

it is just one step more advanced - as you need to know , how to "add-together" morphs (3dMax) = blendshapes ( maya ) ... i dunno know , how this can be calculated within 3dMax , but in Maya you could use e.g. correctiveShape-plugin from www.b-ling.com (http://www.b-ling.com) .

how you can create these shapes in conjunction with "bone-setups" ... one needs to find out on his own - as tim mentioned ... you need to take care of the underlying bone-structure , to calculate your corrective-blendshapes .

------------>
but this also works e.g. for all symmetrical areas ( like the lips of a character or the eye-brows - if, e.g. in cartoon-rigging , exegerated-style ) - once , both ... the leftSide-smile and rightSide-Smile is steered-in , you can add-on a correction , so the lips ( or hips ) finally look as you want them to look ... you can even add "in-between-blendshapes" (maya) , if you want to have "more-smooth-interpolation-in-animation" .

quite a bit difficult to explain , but that is the theory - and it might become quite a lot work to design the inbetween-shapes ... if you are interested more in the theory of this "double-transform-correction" , take a look at this site ... here you can see "why" and "how" (http://dpk.stargrav.com/pafiledb/pafiledb.php?action=file&id=31)

-------------------------
indeed this can be a very advanced-rigging-chapter / i like this discussion , hopefully there will be a lot input in this thread from all of you ... ( i want to improve my hips as well ... and using this technique is also new-to-me , so lets see what ideas the others have )

Kris00
11-06-2008, 02:42 PM
I am rigging a character in max and I want to dosome corrective morph targets for the head for the mouth open and talking. When I add my morph target for the mouch open and go to 100 on it, the character slides off the bones. Can anyone help me with this problem?
I made the mouth open morth target by opening the jaw bone into position, copy the skin, then vert wrangle it into the correct shape, and then added it as a morph target.
Any help would be great?

Kris

DracoDralion
11-06-2008, 04:50 PM
Interesting indeed.


So for this http://www.youtube.com/watch?v=2gkLRhSdZJ0 I went for morph corrections.


I can't watch this video in my country (or at least that's what youtube tells me). Is there another place where I can watch it please? I'm dying to take a look at it.

And thanks for all the input till now

S-S
11-06-2008, 08:55 PM
timothyc:
I have the same video problem as DracoDralion - i'd like to see your video too. Must be some sort of youtube thing....

shalabology:
I'd go with what timothy said. Don't know if you have already seen this thread by Adrian Cher:
http://forums.cgsociety.org/showthread.php?f=153&t=261270&highlight=spiderman+rig

And here's a test a i did some time ago. I was trying to develop better shoulder and hip deformation. Never had time to continue it though:
http://www.cgmill.com/main/wpg2?g2_itemId=3481

timothyc
11-07-2008, 04:21 AM
Okay, you can also download the above-mentioned animation from here (10MB):

http://rapidshare.de/files/40852580/floorRoutine.mpg.html


Kris, in another thread you got a reply from Kees about a free plugin of his called morphx2. I can't recommend it highly enough. In using it you have to rig your own connections (e.g. via a script controller) to automatically control each channel's weight (unlike Skin Morph where making those connections is built into the interface). However, when you want a high level of control over each channel weight, this is actually an advantage - but the biggest advantage is that the blendshapes are stored as vector offsets from the vertex normals, not the way the standard Morpher does it, in which vector offsets in object space move each vertex from it's old, unmorphed position, to it's new, morphed position (Maya's blendshapes work the same way). In practice, this means MorphX can sit above the Skin modifier, which means you can sculpt the morph target in situ, on the actual base object, and in the actual pose whose joint you are trying to correct. That makes for a much more interactive, and therefore efficient, workflow (not to mention far more enjoyable).

What Tony says about using a 3rd blendshape to correct the addition of two other overlapping blendshapes is valuable info and I used this technique extensively in the animation I posted. Most of the time I used a slightly different formula:

mixmorph = sqrt ( 1stmorph * 2ndmorph )

which I think usually gives the best result. ("mixmorph" is what I call the 3rd, corrective morph).

TC

EDIT : morphX free plugin for 3ds max: http://www.lumonix.net/morphx2.html

DracoDralion
11-07-2008, 10:54 AM
Could someone please explain what you mean with blendshapes/morphs by definition. The thing is that I am using XSI and I am not sure how this would be done in it. If you could discribe what happens, that would be great.

And thanks for the new link tim, I really look forward to fiddle around with it.

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