Topology, Maps & Weights (Maya)

#1

Hello All. I have retopologized a character model that I am planning to rig to render-ready completion. If possible do you mind advising on the current topology? The character will need to be able to speak and have some facial expression.






Also - with previous rigs, I have had trouble with weights painted being reset after a save/reload & weights not being able to properly mirror. Does this have something to do with the UV Map or lack-thereof? Should I go ahead and create the UV Map first?

Here is the character with a quick & dirty rig for his demo just for reference/enjoyment:

#2

Oh and thank you in advance for ANY input. Cheers!

Here is what his rig is looking like at the moment, pre-bind:

#3

Biggest mistake, in my humble opinion is… he already has an expression… try something with mouth closed/slightly opened… eyes in neutral “shape/position” everything in “neutral”… he will probably have the most stupid/dull look you have ever seen in your life… but that’s the sing of a good neutral facial expression… but that’s a trap in which people fall really easy… make a model with expression and then try to rig it… bad karma… also I don’t know how strong are your rigging skills… you can have real problems with mouth so big, I would shrunk em a bit, and try to achieve that grimace with a rig (bone based/spline based/ morph-blend shapes/ based) later… if a facial rig can “smile” make an “o” and an “u” expression without falling apart - it’s a good facial rig. Teeth will have to “follow” deformations (size/shape) of his face… imagine him smiling… that will be bloody difficult to achieve. As far as I can see inner mouth/gums/tongue are missing… very important part of a model/rig… so you see… your seemingly simple little character has many hidden “features” and problems… and we are talking about head and face only… not to mention body rigging (what kind of animation you are after?) squash/stretch, bendy limbs… etc. etc…

#4

Thanks. I’ll try to neutralize his expression. I was able to morph his mouth into a decent smile though so that’s a good sign. I knew from the get-go phonemes would be a challenge with this character, but the character simply has a wide face & mouth so I’ll have to figure out something creative there.

The model does have an internal mouth “cavity”, though no gums or tongue at present. I figure that can be added once I start actually doing blend-shapes (which I’ve never done before by the way). Regarding that - all of the tutorials I’ve seen for blend-shapes are just detached heads. Can I select the faces of the head and make copies of just the faces and do blend-shapes that way or do I need to copy the entire skin surface?

#5

Well Maya isn’t my weapon of choice… I know how to do that in Max… all cases, single piece skin, head only, or separate head with facial rig who will transfer vertex animation to the whole model trough morph (blend shape) channel… although I prefer bone based facial rigs (or muscle based in Maya)…these were just general observations from my point of view and some tips for you to watch out.

#6

Hmm. I might need a Maya user’s clarification there on the blend-shapes. I’ve never used the Maya muscle system and there isn’t near as much material out there on it as blend-shapes. I appreciate your advice on the matter… how does the topology look aside from the mouth’s width?

#7

Well this guy knows what he is talking about http://www.hippydrome.com/ArticFace.html … body doesn’t look bad maybe few more loops in bending areas (elbows, knees, hips, shoulders… finger joints) try to avoid those poles and “fake” triangles (reversed quads) as much as possible… I know you must have them somewhere… but if you have to have them, choose lesser of two evils, make them where mesh won’t bend… it will work… you will have problems with that belly…especially in front part of the hip, pole shouldn’t be there, poles are used for parts who are stiff… immovable like cheekbones in face.

#8

To answer your blendshape question, yes you can cut off the head in maya, however you have to make sure the verts are ordered correctly. Your blendshapes will work on the vertex number, so to cut off the head and still make blendshapes you have to make sure your head has all the first vertex’s. This is easy to do, cut off the head so you have 2 meshes, then combine them back again making sure you select the head first, then the body. Now all verts in the head are stored before the body so you can use blendshapes with just the head. Just make sure to turn on check topology.

As for the rest of your mesh, you might want to add a extra edge loop or 2 around area’s that bend. I’m looking at the knees and the elbows and you wont be able to get a nice sharp bend in them. Of course this might be what you want, but thats the first thing I notieced.

#9

Awesome Gnimmel, I’ll give that a go! Thanks.

#10

definitely missing a lot of cross-loops, at every bend point you’d want at least three. Some might say even this is too low, but if you’re not experienced in weighting, that’s the golden rule for every joint (elbow, shoulder, wrist, each finger knuckle, etc).

Definitely gonna have problems with the face, I’d return eye topology back to modeling department (or even back to concept stage), it’s hard to imagine blinks with current model.

Review lip topology. In this model you’d want to model your mouth as wide as eye centers,so you can stretch it out to what it currently is, as well as being able to model “mOde” or “bOOm” shapes easier.

#11

i haven’t used the maya muscle system too but there is a video course for using muscles in maya in digital-tutors.com which I’ve watched.I think it will help you.The character there is also some kind of monster(no pun intended) like a troll or sth.

Introduction to Maya Muscle

Enhancing Rigs with Maya Muscle

#12

This page will give you an idea of how a 2D mesh design can move into a 3D one.

http://hippydrome.com/ArticFace.html

This page can give you a bit of info on just how much an area moves.

http://hippydrome.com/iBookExmpls.html

Cheers,

HD

#13

Thanks for the awesome input. Often its hard to tell myself I need to take a few steps back on a project - but I want to get this one right. I did try some simple blend shapes with the current topo, one of which is a blink - but it does look pretty funky and I’ll have to admit I’m an amateur with the soft mod tool. Here’s a look:

Thanks HD! I researched some of your topology theory a few days back and it was really great information. I’m referencing your mesh designs with my rework on this guy actually. The examples from your book look like exactly what I need to be reading for this character. Hopefully iBook doesn’t mean it will only be available on Macintosh!

So - I’m forgetting blendShapes for now and stepping back to topology. Thanks everyone for the very useful suggestions!

#14

Well I’m buying that book as soon as it gets out…:drool:

#15

Hi all,

Thank you all for all the help provided. At this point I am rigging and creating controllers. I’m running into an unusual issue that I’ve not seen before.

I am adding a RPSolver IK to my character’s arms and I keep getting this anomalous disparity between how the left and right arms are solving. The skeleton is perfectly mirrored and I’ve locked down the channels I don’t want being affected, etc.

I want to run the solver from my shoulder joints to the wrist joints. The L side works perfectly fine, but when I do the exact same action on the R side, once the solver is snapped to the wrist joint, the upper arm joint pops out of place, causing an imbalance between the two arms which is further distorted by moving the handles, etc.

If I have perfect balance, why is one side behaving differently than the other? The pop itself wouldn’t be a huge deal if both sides did it, but I can’t have just one side doing it…

Any ideas what is causing this or how I might go about resolving this?

Thanks in advance for ideas.

#16

I guess your problem might be from the pole vectorX, Y and Z attribute on the ik handle itself. Try resetting all of them to 0.

This might fix your problem,
BUT!

*if you dont mind, take my advice below

First off, I don’t think it’s a good idea to have more than 3 joints on your arm ik.

The wrist joint doesn’t have to be a child of forearm joint, both the forearm joint and wrist joint could share the same parent -the elbow joint. So now, your joint chain should look like this.

shoulder>elbow>forearm and wrist

It’s tricky drawing joint for ik, espacially for an A-pose character.

If you plan on stretching the ik, which is a must for a toony character, you might wanna check your joint orientation to have an axis (X) pointing down the child joint.

Another important point to keep in mind is, the aiming axis MUST be exactly in-line. So, how ever you move the ik, only 1 rotate channal(Y) the elbow joint’s going to change. If not so, you might find yourself having hard time trying to find the right spot to place your poleVector control without the joints poping. AND, it’s impossible to do ik/fk matching.

#17

Thanks for the advice, especially the forearm joint - I’ve never considered that the wrist wouldn’t need to be it’s child. I’ll work with the joints’ orientations to make sure they are correct. I use the Comet script and manually tweak thereafter. I checked the pole vectors on each - zeroed them out and it made no difference.

I understand the difficulty with spanning >3 joints, etc. I guess I just like the deformation and control I get going from shoulder to wrist.

My beef with the rig at this point isn’t really a question of my technical approach however. My problem is that given equal and exactly opposite joint configurations - in position, orientation, and degrees of freedom, logically both sides should behave exactly the same with the IK solver applied - but in this situation it doesn’t…

I’m experimenting right now with recreating the skeleton with some tweaks…

edit - after deleting and re-mirroring the arms, something is definitely up, it isn’t mirroring properly across the axis from either side.

#18

Try draw a brand new joint in straight line(x, snap to grid) from the front view.
Position the root, in this case, the clavicle. Only use rotate to align the joints the the limb(on the elbow and wrist don’t touch rotateX and Z).
Freeze transform, make sure in the option box translate rotate and scale is checked.
Don’t parent the chain to the back joint yet, mirror it(also check the options to mirror across YZ and check on ‘behavior’).

This should do it.

#19

Thank you for the suggestions. I did end up just deleting the arms and re-drawing them in the same space which resolved the issue.

Now I’m just trying to export/import the weight maps from the previous skin which I’ve also never done before. I could just repaint the weights - but I’d like to learn the correct procedure for export/import. It seems that a lot of the skin is being pulled to the origin after being mapped onto the rebuilt skeleton. Is this possibly because the map isn’t normalized?

edit: never mind, F1 is your friend :slight_smile:

#20

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.