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View Full Version : how to copy weight maps from one object to another?



KeithJ
02-27-2004, 12:10 PM
Hi,
I have been working on a figure and have several versions of it. However the best version does not have the best weightmaps. I was hoping I could copy them over but am struggling. I looked on flay.com and found TWMC which crashes modeller, also "BoneWset" which seems to do nothing. I also found weighter which doen't appear to do what I want.



Anybody any ideas?

Or should I just start drawing my weights over?:mad:

Keith

wingwalker
02-27-2004, 03:44 PM
Ive never seen anythig that would copy weights from one object to another.

You could do the maps again in the time you would take looking about for a solution.

And you also have the benifit of knowing what you are tring to achive!!!

Good Luck

Rob T

SplineGod
02-28-2004, 12:23 AM
Check on flay.com. I think theres a plugin or two that can help. Heres a link to one called Weighter:
http://earthwormjim.free.fr/lscript/modeler/weighter.html
and this one:
http://www.flay.com/GetDetail.cfm?ID=1173

KeithJ
02-28-2004, 05:58 AM
Thanks people,

but I think it looks like wingwalker may be right.

I already have the two plugins SplineGod suggests and as I said I "found TWMC which crashes modeller" and "weighter which doen't appear to do what I want" (It copies weights but only through one axis)
So here I go again

Keith

SplineGod
02-28-2004, 10:31 AM
One suggestion is to simply or not use weight maps.
I rarely use them and if I do they tend to be simple enough to easily reapply. :)

KeithJ
02-28-2004, 06:51 PM
You don't use weight maps on figures? How do you prevent the mesh from caving in where you don't want it to?

If I could get that to work it would be worth a try!

Keith

SplineGod
02-28-2004, 07:05 PM
I rarely use weight maps. Its a MYTH that you HAVE to use them when rigging characters. :)
You can add weight maps at any time so why add them first if theyre not needed?
After you create your basic bones and have rested them then you can determine where you have unwanted deformations.
First thing I do is set the bone falloff to ^128.
Make you first pose on some frame other then 0.

Make sure you have a rest pose of your character on a negative keyframe. This is a good thing to do if you screw something up and need to rerest your bones. If you dont have an original pose it can make fixing the skeleton a pain.

Someplace like frame 10 is a good place to do a test pose. Try starting by rotating the arms down to the sides.
Is the armpit collapsing? Go back to frame 0 add in a couple of rib bones that start at the spine and point towards the armpits.
Rest (r key) those new rib bones on frame 0.

Go back to your pose position. Slowly change the rest length of one of the rib bones until the armpit behaves. Make the same adjustment on the other one.

I usually do this to hold the pelvis area and butt better with a hold bone or two. Its even easier to add a couple of hold bones to keep the head from being effected then to mess with weight maps.

If I use weight maps I keep them VERY simple...maybe one for both arms and one for the rest of the body.

When modeling keep the fingers , arms and legs spread a little to avoid bone cross influence. Doing that is easier and faster then messing with weight maps again.

Heres a good thread that shows that you can get great deformations with no weight maps. How many people have a tough time getting the shoulders to deform properly?
http://www.cgtalk.com/showthread.php?s=&threadid=95214

KeithJ
02-28-2004, 07:14 PM
This souns incredebly timesaving. I will have to check it all out.
I wonder if this method will also work in motionbuilder.. I literally started testing it this week so I know virtually nothing about it.

Thanks very much :)

Keith

SplineGod
02-28-2004, 07:25 PM
It is a huge timesaver believe me. :)
As far as motion builder goes I dont know if it cares
if you use weights or not to when animating.
I do all my character animation in LW and havent
had a chance to really screw with MB. :)

KeithJ
02-28-2004, 07:33 PM
Well it is certainly very powerful. I had no intention of using it until I realised that its going to be a long time before LW8 comes out. The automated rigging system is what attracted me. It defiantly references weight as it was discussed in one of the instructional avis I got free with 3Dworld mag.

I suppose I will have to delve into the help files to see if I can enhance the auto rigging.

I know it can use morphs and such so I will let you know how I get on.

Keith :D

KeithJ
02-28-2004, 07:34 PM
Oh I forgot.. The realtime feedback makes it very attractive!!

SplineGod
02-28-2004, 08:12 PM
Ive done a ton of character rigging and animation in LW. I dont have problems getting around the feedback issues. I just prefer to keep my pipeline as simple as I can. I dont like jumping between apps. :)

drfoley
02-28-2004, 11:51 PM
I read your previous thread on CGTalk. I'm having a problem with twisting in the wrist area. I'm not sure I understood what you were saying about 2 child bones in each joint; the hold bone and the seperate rotation(twisting) bone?

How would that look? Could you post a closeup of a picture with a properly setup wrist?

Heres what I've got. I can use Follower but cant get it to look good with a 180 degree rotation. Thanks.

SplineGod
02-29-2004, 12:01 AM
Wrists dont really twist, the whole forerm does. So you would want a small forarm bone just for bending the elbow and not twisting. then you want a 2nd or even a 3rd forearm bone to distribute the twisting between the elbow and the wrist.
You would then have a wrist bone for bending in the pitch and heading. Hopefully that makes sense.
Generally I dont use joint bones for twisting, just for bending.

Dodgy
02-29-2004, 10:33 AM
I agree with everything SG has said, I only use weightmaps in very exceptional circumstances, the rest of the time Lw's bones do a good enough job.

The one comment I would like to add is if you're looking at the shoulder on his little tute, I would use a bone for the shoulder blade, coming DOWN from the tip of the shoulder, not pointing up from the waist as he has shown.

I have a bone coming out from the spine about waist height, and a little bone on the end of that called 'shoulder_blade_target'. I then target the shoulder blade bone at this (obvious!) and as your character's shoulder swings up and around, it makes the back move appropriately, and keeps the armpit from pinching as the arm swings down.

KeithJ
02-29-2004, 12:57 PM
Larry,

you've realy got me wondering wether I'm waisting my time with the evaluation copy of motionbuilder. It seems I will have to learn an awful lot just to be able to do a lot of stuff I can do already. And I really don't nead the extra expense.

The stuff you talk about on rigging joints without twists is something I thought about a lot (and motion builder's auto rig doesn't seem to address this at all). Looking how a thigh and hip interact is a good example.In an earlier rig I made I tried to emulate this joint (see_pic). You seem to endorse this king of rigging. Am I correct?


Keith

SplineGod
02-29-2004, 02:22 PM
Thats why I havent bought motion builder. So far I can rig and animate just fine in LW.
Heres the way I rig the hips and shoulders actually.
This created a 2D IK situation which is more stable and faster.

KeithJ
02-29-2004, 06:08 PM
I'm starting to see your point more and more Larry.

I see I was working along the right track with my hips, but would you show me a couple of elevations of that setup please as its quite difficult to see the angles that the bones have in relation to each other.

When I first started this (about 3 weeks before christmas) I was trying to base my joint locations and shapes on a real skeleton. The only one I could find that seemed reasonably acurate was in poser. Was I correct to do this?

I notice you have the hips unaffected by IK. Are they parented to a sub pelvis bone that allows them to swing?

I started doing something similar (as you can see below).I control the hips swing with FK keyframes as I found IK was moving the feet around too much when they should have stayed planted. So I then used the 'Hip height' expressions on the pelvis bone graph editor( to make the hips drop as the legs move apart) and that improved things a whole lot. But I still find foot movement to be something of a problem. I've seen and tried a couple of foot setups where the feet were not parented to the legs. The Ik was controled by a combination of targets and expressions( like the IK set up 'Advanced character.lws' that came with LW). However I found that there apeared to be an amount of unatural stretching around the ankles going on.

I suspect the answer is something to do with where I place my targets and their strength. I currently do something similar to the method recomended by DAn Alblan in "inside Lightwave" but I am unsure as to if this realy is the best way.

Any recomendations?

Keith :confused:

drfoley
02-29-2004, 10:50 PM
I've never seen that before. So the Shoulder target bone comes out horizontally at the waist? There must be a thousand different ways to rig out there. Got an example rig you could share?

Thanks,
DrFoley

SplineGod
02-29-2004, 11:04 PM
The two white bones I have at the waist are the parent bones for the lower and upper body chains.
I have the bone chain for the upper body separate from the chain in the lower body.
The thing to remember about rigging is that you are constructing a control framework that will allow your character behave according to a set of requirements. The part most people miss is what makes a good rig? Rigging is not about IK, Bones, weight maps etc. Its about using those tools to make a rig behave a certain way.
Too main people focus on the technical aspect rather then the philosphy behind what makes a good rig good or a bad one bad.

The philosopy or guidelines to rigging are essentially universal from package to package. The only difference is in how each package is set up technically to meet these guidelines.

Once a rig behaves properly then you have other aspects such as muscle and skin deformations but those are driven by the basic rig itself.

This is why the character rigging module of my 4 part character series is about 15 hours. I base the whole module around what I call the 12 principles of rigging. :)

KeithJ
03-01-2004, 03:19 AM
Just wish I could afford that CD.

I'll have to save up (while I'm in a forum I may as well ask.. just how exactly do you do that?)

Keith:confused:

SplineGod
03-01-2004, 11:15 AM
How do I do what?
Also, email me if you are really really interested in the rigging CD. :)

KeithJ
03-01-2004, 04:55 PM
Sorry Larry it was my sense of humour (I'm British and I know it doesn't always translate). I meant how do I save up enough money to buy anything (what with all the bills I have to pay and so on... )? But you really don't want to hear that!

:D

I am intersted in the CD so I will mail you.

At this point I must thank you for your welcome insight into the rigging animation/ software issues.

Keith :)

SplineGod
03-01-2004, 07:59 PM
Doh! Gotcha. Got yer email too.
Youre welcome. Rigging is definately not an issue that can be solved on a forum :)