View Full Version : Hair system- hair problem

04 April 2005, 11:05 AM
Hi ! I've been trying for a while to create a decent long hair with maya hair system.
The results is prety good,is fast, but I have allways problems with deep shadow map and for that thing
I was looking for something else.I tryed Joe Alter's Shave and haircut but that tool doesn't compare, in my opnion,
with Maya hair system wich is more suitable for creating long hair.So I just come back to the maya hair
system and I found MR_hairSystem from Provide3d- an excelent geometry shader wich allow you to render
with mental ray maya paint fx or nurbs curves---but this is taking to long to render and some time maya crash
( 3Ghz P4 + 1.5 Ghz ddram)

question : If you worked with maya hair system wich is your best result( time + quality) and how did you achieve that?

04 April 2005, 07:34 PM
In order to get self shadowing of the Maya hair one needs to adjust a few things on the shadow map( though perhaps you've already tried this ):

Mid Dist maps need to be off.
Then make the filter size something like 4 or greater
( this smooths the shadow boundary and helps simulate scattering into the hair ).

The dmap bias then needs to be set to a good value. One would use somewhat larger
dmap bias and filter for lighter colored hair, as it allows more light penetration.

It is also helpful to manually set the dmap focus and also make the shadow map resolution fairly high.

Also for better antialiasing of the hair turn on pfx oversample and post filter in the render globals.


04 April 2005, 06:41 PM
Hi Duncan, I have a shading question want to ask you...about hair.
I have find that hair default is a "thinLine" type brush pfx. After I attach a brush to my hairPfx, I can change to "paint" throught the new brush node. And I switch on "illuminated" , my hair than have normal shading now, but the shadow is not soft as thinline type..
My question is can I change my pfxhair brushType directly? or I must need to attach a brush to it?. and After the pfxHair has a brush attached, which parameter will affect the hair in the brush node?
And how to sovle the shadow problem?

04 April 2005, 04:36 PM
I am having problems with hair also. First I was using Maya Hair in Maya 6.0.1, it looked great in still shots but when I started animating hair on the side of the head that was not dynamic and pressed back (tied back) was flickering and disappearing behind the head of my character. The camera is on the side so the character is about 2/3 the height of the frame. the hair first disappears around frame 12 as the camera changes position slightly, so the first 11 frames seem fine. I have 2 characters in the scene both with similar hair on opposite sides of the frame and there is a problem with both of them.

Because of this I have started to learn Shave and a Haircut, which so far seems very nice for rendering loose hair, but my characters have tied back hair, ponytails, and clumps. Is there a way to create a pony tail in Shave and a Haircut? I cannot find any tutorials on this program. I tried multi strand but does not seem to work well with multiple passes on the hair.

04 April 2005, 10:48 PM
My question is can I change my pfxhair brushType directly? or I must need to attach a brush to it?. and After the pfxHair has a brush attached, which parameter will affect the hair in the brush node?
And how to sovle the shadow problem?

You need to assign a brush to change the brushType. Hair has a default brush that it uses if not brush is assigned. The hairSystem overrides some of the brush attributes, for example brushWidth, color1, translucence, specularity and multistreaking. There should be something in the hair doc describing which attributes that are overridden. In general if you assign a default brush, turn on illuminated, make the global scale 1 and make the brush type thin line you should get a match.

In terms of shadows you may see a dramatic difference if you have are using multistreaks. The thin line brush will uses multistreaks, which can reduce the intensity of self shadowing in some cases. However multistreaks are ignored by other brushtypes. Thus you would also have fewer hairs.

Another attribute you may wish to adjust is translucence( on the hair system). The thin line draw has no lambertian shading effect(like an opaque tube), however the paint brushType does. The paint type needs the translucence to be 1.0 to get rid of this effect( in general with hair we do not want each hair to be shaded along its width.. light tends to just pass right through it.. the shading also creates anti-aliasing issues).


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04 April 2005, 10:48 PM
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