Hair Modeling

[steve-o]

Hey everyone,

I was wondering if anyone had any good suggestions about creating hair on a female model. I have done hair in Houdini using curves and they worked fine howerver they were static and stood straight up (it gave a more fur like representation). I have never done hair on a human before and I have never animated the hair.

Any help would be great. I am trying to use houdini more than maya and this is one of the bigest hurtles I need to get over.

Thanks

Steve-o

[peship]

Well, i think i can help you a bit here.

I will tell you what i did ago and hopefully this could be helpfull in one or another way for you.

It's the common workflow - startCurve, restCurve, dynamiCurve + per-primitive/per-point control + tools to manage the data and objects. The data flow is split between hairSystem, hairFollicle and hairClump operators.

The hairFollicles contain the dynamic/rest/start curves. You can use ( edit/reshape ) the built-in curves, or connect to the follicles geometry containing curves modeled in other 3D apps, each hairFollicle will pick-up only one unique primitive from there.

These operators allow and fine tuning of the dynamic properties of the curves using constant values or animationCurves ( for per-point control along the curves ).

The hairClumps contain the actual curves which will be rendered. These operators basically "instance" geometry along the dynamicCurves, add some variation to the shape, thickness, color, shaders are applied to them, etc.

All the hairFollicles get connected to hairSystem node. It collects all the dynamicCurves and sends them to the DOP network, DOPs do something with that geometry and send the simmed data back to the hairSystem. The hairSystem propagates the changes to the follicles. Also hairSystem allows global control over the whole hair setup.

The workflow is based on overriding of settings and is like this: set-up the globals from the hairSystemOp, then tweak here and there using hairFollicle and hairClump ops.

Also, the hair operators can read pointAttribs from the scalp geometry to which they are stuck to. So you can paint baldness, scale, color, dynamicProperties, etc along the surface. It can get really slow tho. Anyway, this is simply another level of control over the look/behaviour of the hair system.

I can go into more details, but at this point i feel it is not neccessery.

If you are somehow interested i can handle you the stuff.

[steve-o]

Thanks,

I can use everything that you can give me but I have one more question. Do you use another package to get a rough outline of the curves or do you just know how the curves are to be laid to make the hair style?

Thanks for responding! (it somewhat making more sense)

Steve-o

[peship]

Steve, i am sorry for the delay.

Yes, i use other software to style the hair. And it's not just to get some rough shape, but for really fine tweaking - literally point-per-point adjustments. In addition are needed lots of deformers, dynamic goals, cache blending, hand animation, etc - otherwise the things simply do not work well ( talking about long hair here, but even for fur you need quite a bit of the same before running the solvers ).

Tonight i will give you a link to the stuff i promised.

Edited May 14, 2007 by peship

[steve-o]

peship,

Thanks again for your help. When you send me the links can you also possibly give me some names of packages that you use to get the hair patterns.

Thanks,

Steve-o

[peship]

The old school hair styling app is ShaveAndAHaircut. But these days Cinema4D offers better tools. Both they are good to edit multiple curves at once, this way you can model the big volume of hair ( or wide areas covered with hair/fur ) relativelly fast. If you need to mach some exact look, the last stage is always pushing points by hand - usually this happens in the software you plan to use for simming the hair. Many people/studios stick to the points pushing approach only.

http://www.petershipkov.com/temp/longHair1.0.tar.gz ( ~37 Mb )

The archive contains otls, example scenes, motion captured animation, two image sequences showing the stuff in motion ( no hair style or whatsoever ) and bgeo file with much better looking hair. In fact i am not sure if that's the exact content, but should be.

As the most personal projects it misses the last 10% - usually good looking examples showing what the product is capable of. Which is understandable - at the moment i proved to myself that the thing works i lost interest

The good looking hair geometry was supposed to be the missing 10%.

I am using the default vex hair shader - it is not very good, but i had problems with Arno's hair stuff ( he gave me permission to use it ), it keeps saving the otls inside the hip file, even i instructed H to not do that.

Edited May 15, 2007 by peship

[sibarrick]

Hi peship, I was trying to look at your file, the download seems to be missing $HIP/styledHair.geo, also when I open the hairTest3 hip file I get lots of warning about overlapping keys, is that right?

cheers, looks interesting, i'd like to see it working properly.

[peship]

I will check for that file tonight.

The warning messages have something to do with trash in the scenes, carried out from an old H release(s) which had some problems with this kind of stuff - just ignore them.

And thanks for the kind words

[peship]

http://www.petershipkov.com/temp/styledHair.geo