PDA

View Full Version : Simple rigging help - blows up mesh



Algae998
02-12-2010, 01:55 PM
Hey LW'ers

Ive been trying to figure this out for a few days now but I cant figure out what Im doing wrong. Im pretty sure my workflow isnt good but Im hoping someone can spot it. Ive uploaded 3 screenshots of what Im talking about.

I started by making my rig in modeler with skelegons. The hierarchy wasnt perfect but I fix that once Im in layout, otherwise the skelegons snap to the position of their parent in modeler.
Once I finished making the skelegon rig, I went through each bone and hit Edit Skelegon and grabbed the handle and rotated them so they were facing -Z or +X (image 1).

Once all of that was done, I sent the object to layout and converted the skelegons. First thing I noticed was that on most of the main bones (upper arms, fingers and some of the leg bones) had some pretty bad gimble lock or the axis had been swapped (image 2).
Is the Edit Skelegon feature supposed to correct that, or did I do that wrong?
I figured since there was such bad gimble lock, Id go through the worst ones and record the pivot rotation after I turned the bones off.

I finished correcting the hierarchy and setting up all the proper weight maps. The gimble lock seemed to be corrected until I hit Enable Deform, which turned the mesh into jelly (image 3).
I havent done anything fancy like installing IK or anything yet.


On a side note, the character's eye is in the middle of the torso. Should the eye bone be parented to the middle bone of the 3 spine bones?


If anyone can point out what Im doing wrong, Id greatly appreciate it.

4dartist
02-12-2010, 02:17 PM
Try grabbing ALL of your bones and hitting 'r' or Record Bone Rest Position

That should snap the mesh back into place.



EDIT: I should also mention once you do the 'r' bit; if you had any bones disabled they will now be enabled, thus you need to go through and uncheck them again.

EDIT:A tip about gimble lock areas that I use all the time would be to add a second dummy bone at the shoulders and wrists. So you have your collar>shoulder_antigimble>shoulder>elbow>arm_twist(in the middle of the forearm)>wrist>wrist_antigimble>fingers. I came up with this to get myself out of a gimblelock if the problem arises. I'm sure there are other possibly much better techniques, but it works for me.

EDIT: Thought of something else. To control which direction your pitch is on your bones, I find doing it in modeler using 'Edit Skelegons' pretty good. Just bring up polygon tool, select the first bone in a chain, and click 'Edit Skelegons'. Then you can grab the lollipop looking thing and that is basically where pitch will go. Bank is always the same, perpendicular to the bone, and heading will be rotated off 90 from the lollipop but down the direction of the previous bone, so to get the heading to align down the bone you can use 'Align Pitch' in layout (not modeler). That last bit is pretty optional though.

SplineGod
02-12-2010, 03:18 PM
Along the same lines...
I generally use two bones on a universal joint like the shoulders and hips. One small bone points down the z axis and gets bank IK only. The thigh bone for example would get pitch IK only. This will insure that you dont get gimbal lock on universal joints. On hinge joints like a knee or elbow you dont need to worry about gimbal lock.
Make sure your character has a rest pose you can go back to when you ever need to rerest your bones.

Algae998
02-12-2010, 03:30 PM
Try grabbing ALL of your bones and hitting 'r' or Record Bone Rest Position



EDIT: Thought of something else. To control which direction your pitch is on your bones, I find doing it in modeler using 'Edit Skelegons' pretty good. Just bring up polygon tool, select the first bone in a chain, and click 'Edit Skelegons'. Then you can grab the lollipop looking thing and that is basically where pitch will go. Bank is always the same, perpendicular to the bone, and heading will be rotated off 90 from the lollipop but down the direction of the previous bone, so to get the heading to align down the bone you can use 'Align Pitch' in layout (not modeler). That last bit is pretty optional though.


Thanks, I turned the bones off and hit the Record Bone Rest Position and that did bring the mesh back into place. :thumbsup:
I didnt realize that the lollipop controlled the pitch orientation, but it makes sense after hitting "r". Definitely keeping that in mind for next time.

Can I use the same control to give more bias on the bones for IK? For example, prebending the arms and knees more so I dont get IK popping? I thought I installed enough bias when I drew out the skelegons in modeler but I guess it wasnt enough.
Would that be a matter of turning the bones off, rotating the upper and lower legs into position and recording the bone rest position?

I tried something similar to that but when I turned the bones back on, it left the bones in the same prebent position, rather than snapping them back into the leg. So rotating the bones made the mesh deform around the new bone position..

I could never get the order or operations right in rigging :grumpy: haha

4dartist
02-12-2010, 03:53 PM
It takes a lot of working with this stuff to really get a feel for it.

Record Bone Rest Position works like this: It will always say to the bones, "You are now at your default place, so I'll(lightwave) pretend I haven't bent/deformed you at all and put the mesh back to the way it is in the model file."

So if you bend the knee and hit 'r', basically your model with snap back to the same as your model file but your bone will be sticking out of the leg. (ouch) So that's the wrong approach.

If you want to pre-bend your leg for IK, it's possible I guess, I can help you through it if you really find you need it. However, if you make sure your pitch on the knees is right, and you already have a slight bend you should be ok. If you have 0 bend, than yes you need to induce some.

With the basic bones, something you should know is to control the angle of the knee, you can use a fancy 2nd IK trick where the knee points to a null infront of the character, or do a quick and easy thing I learned in Tim Albee's book I think long ago. Just make a tiny little bone right be fore the big thighbone. Make it point basically in the same direction. This will keep the hip from gimbling during IK use too. The important thing is to use the 'Unaffected by IK of descendants' check box in the motion properties ('m') panel, on that tiny bone. This has to be checked. Then to animate the direction the knee points just animate this bones bank rotation.

4dartist
02-12-2010, 04:01 PM
Oh.. if you ever accidently hit 'r' on a bone while animating and your characters head pops off or foot is suddenly up his arse, you can fix it pretty easily. No.. not undo. :( Here is how I do it:

Find your stock rig file. locate that bone, and write down the exact rotations in the rest pose. Bring up your scene file that has the messed up skin over the bone you hit 'r' on. Put in those rotations. If it's an IK boned, just quickly toggle off IK, and put in the numbers. Then hit 'r' again. It should do the trick.

Sometimes I keep the entire rig keyed in the rest pose at like -100, just so I can refer back to it or copy keys out of it.

Wow this has been random thoughs.. lol

Algae998
02-16-2010, 04:00 PM
Thanks for all the help, its certainly been useful. Ill have to keep those tips in mind if I run into them. Im trying to bash my way through rigging haha.

Do you think its easier to use skelegons and covert them to bones in layout or just use bones?

4dartist
02-16-2010, 04:07 PM
Oh, skelegons for sure. Much easier to make quick placements and adjustments to get the bones in the right spot. Then edit lolipops, and convert. If you notice problems or goof ups right off the bat, just delete those bones, edit the skelegons, and re import. But once you have put a bit of time into your actual bones, editing them in layout makes sense.

for small rigs or less organic rigs.. just making a null, hitting '=' a few times (which is make bone I think) and editing those can be really fast.

Say you messed up an arm though, but you put a ton of time into the rig. Cake. Just delete your arm bones, go to modeler, make the fixes to your skelegons, put just those skelegons you want on their own layer, then convert them. The AWESOME thing about newer versions of lightwave is you can move bones from one object to another. :)~

SplineGod
02-16-2010, 06:16 PM
I actually prefer just drawing the bones in layout. You can save and reuse rigs there also using RIG files under the setup tab.
Once I get the bones setup with controllers and muscle bones I dont like to go back to modeler since any changes dont take into account whats applied to the bones in layout. :)

Algae998
02-24-2010, 04:38 PM
Thanks a lot, Ive been taking and adjusting my notes on this. Slowly getting more comfortable and understanding it better..still basic, but it works.