strand hair for MH models in Blender

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strand hair for MH models in Blender

Postby punkduck » Mon Nov 07, 2016 6:16 pm

This is a short tutorial on hair-do using Blender strand-hair, as in the last tutorial this text is more a "tips and tricks" than a real tutorial. My goal is a hair-do for a scene in Blender, not for a film, where you will need hair-physics as well.

When using strand-render you had to understand the principle in Blender. Hair-physics is done with a particle system, where you can see the path a particle would fly. This path is rendered as a hair. There are many manipulators to change the behaviour of the hair.

Hair can also be used for carpets or for fur. If you've seen my pictures, the teddy bear also uses hair or the stripes on the fur-coat where made with hair-physics. And the teddy was my first object to mess around with strand-hair. So for all people who never tried strand-hair, watch this tutorial and build your own teddy ...

https://www.youtube.com/watch?v=LCghBIUZyuM

One of the big problems is to model hair, especially for female hair styles. I tried different methods, but I often ended up in a mess ... especially, when I started to comb my models ... when you comb one side, the other side sometimes was destroyed etc.

So after watching this video:
https://www.youtube.com/watch?v=WVJyGzPJIeQ

I decided to concentrate to one of the leading thoughts in this video. It is the use of different hair sections. I reduced that to 3 sections. A left, right and a back-section. In the following picture you can see, that
these sections may be different between models. Dani also got a 4th section to create eyebrows, furthermore her right and left hair-sections are unsymmetrical.

hairdo1.png


To create a section simply select the skin, go into edit mode, select the vertices you want to use and duplicate and separate them from the skin. Change the name to something like "hairleft" etc.

Before adding a particle system to these sections, I made some geometry changes.

First I scale down the sections, so that they are completely inside the character. The main reason for that is, that I use a transparent shader for these parts. If the transparent faces and the normal skin faces were absolutely in the same position, Blender cannot decide which face is valid, so that you are able to look in the head in some places.

I also make the hair-sections overlap, where I want to have parting in the hair. This helps a little bit to avoid gaps.

The next picture shows all parameters for my model Evi:

evis_hairdo.png


When you change the order of particle system and subdivision-surface modifier, the styling of the hair will be destroyed, when you toggle between particle edit and object mode. It took me some time to find the reason for that ...

I used two different parameter settings for the hair sections. The hair in the back is longer than the left and right side and it should appear curlier. So I made changes for some parameters (marked red).

If you think the number of children appears low, always think of the number emitted hair strands and the small size of the hair-sections (30000 hairs each side, 50000 in the back). This sounds small, but the real number is between 80000 to 121000 (german Wiki article, in the english article I cannot find these numbers).

I also add my information of Leska and Dani. Leska is not very different to Evi, the only problem was to make the color for the red hair.

leskas_and_danis_hairdo.png


Leska settings:
back - 5 Segments, Hair-Length 2, 30 children, wave, a thickness of 0.4 to 0.2
left, right - 5 Segments, Hair-Length 1, 40 children, no kink, thickness of 0.4 to 0.2

For Danis hair I used less hair to make it fluffier ...
Dani:
back - 5 Segments, 350 hairs, Hair-Length 4, 50 children, radial
left - 5 Segments, 350 hairs, Hair-Length 4, 50 children, radial
right - 5 Segments, 350 hairs, Hair-Length 3, 50 children, radial

I added her setup to the picture. It was some kind of experimenting. In reality she looks different. I also tried the color of blond hair. It normally starts darker at the root and ends up in a lighter tone. In some pictures her hair looks more grayish than golden blond. But when you make photos for a magazine you will naturally try different light setups. So my interpretation might be wrong.

So especially for the hair colors ... good ideas are welcome.

In future I will create different hair styles (but no braided pigtails, I don't like them :mrgreen: ). And it is like reality, the hair style of the real model always looks different from photo-session to photo-session. And obviously I took the less complicate styles. ;)
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Re: strand hair for MH models in Blender

Postby o4saken » Tue Nov 08, 2016 6:07 am

"to create a section simply select the skin, go into edit mode, select the vertices you want to use and duplicate and separate them from the skin. Change the name to something like "hairleft" etc."

Have you ever tried doing your sections using weight painting instead of selecting vertices - i used to select vertices, but found that with weight paint you are not confined to squares, thus you can get a very smooth hairlines.

Otherwise, excellent tutorial!
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Re: strand hair for MH models in Blender

Postby punkduck » Tue Nov 08, 2016 12:28 pm

o4saken wrote:Have you ever tried doing your sections using weight painting instead of selecting vertices - i used to select vertices, but found that with weight paint you are not confined to squares, thus you can get a very smooth hairlines.

Otherwise, excellent tutorial!


First, thanx for the appreciation :)

Yes I also use the method with weight painting, e.g. for the fur coat in "cold makehuman winter". In the beginning I was working like that for the hair-do as well

... but: my reasons to duplicate the skin are these:

  • I create the hairstyle only one time, but I have at least two different models for the shoes and a "barefoot" version. So I can "copy" the hair styles from model to model because they only differ in the shoes.
  • the selection of the part you want to comb is easier ... (at least in my opinion ;) )
  • especially for eyebrows it is better to have own faces, so that you can shrink them to the size you want. Weight painting only allows one value per vertex ...

But you can combine the methods, weight painting can also be used on the extra faces using an own group of course.

I hope other people will show their ideas as well. I'm especially interrested in good ideas considering the hair color ...
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Re: strand hair for MH models in Blender

Postby o4saken » Tue Nov 08, 2016 1:42 pm

punkduck wrote:... but: my reasons to duplicate the skin are these:


well i suppose one could still duplicate the scalp then do the weight painting - i disagree that it is difficult to comb, because multiple weight painting can be assigned to multiple groups, then the hair is assigned to the specific group.... anyways everyone has their own style :D .

i will update (tomorrow) my post with a screen shot of how i do the node setup for particle hairs colour - nothing fancy, but i like to add an index of refraction - with the settings correct when you look at the material on the left in blender , the ball looks semi translucent with a darker shade at the core - I think that real hair is more like that, where the outside of the strand of hair is semi translucent, but the main colour come from the core.
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Re: strand hair for MH models in Blender

Postby Mindfront » Fri Nov 11, 2016 2:41 pm

Thanks punkduck for a great tutorial!
This is just what I need, soon it is time for me to do hairstyles. Primitive: "Curve Segments', I have never understand what it means until now.
I'll download for offline reading.
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Re: strand hair for MH models in Blender

Postby o4saken » Fri Jan 27, 2017 1:48 pm

node.PNG


This is the node setup i use for the hair, obviously the difuse is the main colour, the transmission is a lighter version of difuse, but the rest all stays the same.

here is the result, never mind that she is a bit bald - needed to add more hair, but it works for the example.

hair.png


The parting is done with weight painting assigned to 2 different vertex groups.
first i start with painting the entire scalp where i want hair.
cleaning up.PNG
cleaning up.PNG (140.77 KiB) Viewed 5556 times

Then make a copy of the vertex group, and subtract weight paint the one half, also cleaning it up while i am at it.
other side removed.PNG
other side removed.PNG (43.99 KiB) Viewed 5556 times

go back to vertex group with everything selected, make another copy and repeat for other side
one side removed for path.PNG
one side removed for path.PNG (75.65 KiB) Viewed 5556 times

then add particle hairs to the different vertex groups.
assign to vertex group.PNG
assign to vertex group.PNG (14.03 KiB) Viewed 5556 times


This process can also be done on a scalp cap allowing the hair to remain seperate from the model.. actually this works quite well because if you move the hair to a seperate layer, once blender has finished rendering, you can use the node setup to post composite, and a RGB curve and make slight tweaks to the colour of the hair you obtained.
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Re: strand hair for MH models in Blender

Postby punkduck » Fri Jan 27, 2017 10:37 pm

Hi

Yupp, painting the scalp red is exactly the same as selecting the faces and assign them to a vertex group with a value of '1'. I'm using the weight-painting method e.g. for pubic hair (for length and density), but didn't show that to the MH audience. :mrgreen:

I played around with overlapping areas or tilting these extra-areas to get a version with less problems to avoid baldness. I had exactly the same problem for my blond 'Dani' character. And since I had 3 different 'Danis' because of the heels ;) the cap method was a good idea not to create the haircut three times.

But I will do some experiments with your shader setup (and still hoping for a better blond one), nearly I forgot, your model looks good by the way with that special makeup ... :shock:
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Re: strand hair for MH models in Blender

Postby Mindfront » Sun Feb 05, 2017 3:47 pm

Here is a close up render and screenshot of the hair and particle settings I used in my scene "The guitar player". I always use metric scale 1:1 in Blender.
I used a simpler hair settings for what I call "fjun". I use Cycles and a procedural texture to give the hair some color difference.

Many problems I had when trying to learn doing hair by watching tutorials is that they dont mention wich scale they using and scale is very important when doing hair particle settings.

Hair.png
Hair settings
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Re: strand hair for MH models in Blender

Postby punkduck » Sun Feb 05, 2017 10:24 pm

Mindfront wrote:Here is a close up render and screenshot of the hair and particle settings I used in my scene "The guitar player". I always use metric scale 1:1 in Blender.
I used a simpler hair settings for what I call "fjun". I use Cycles and a procedural texture to give the hair some color difference.

Many problems I had when trying to learn doing hair by watching tutorials is that they dont mention wich scale they using and scale is very important when doing hair particle settings.

Hair.png


The small braided strands and the topknot (or bun) are most impressive. Until now I didn't know that this is possible with Blender. The problem with the scale I noticed, when I shrinked my models to Joel's "fashion box" to do the improved render.

As always I now got a few more ideas for the future ... ;)
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Re: strand hair for MH models in Blender

Postby Mindfront » Sun Feb 05, 2017 10:50 pm

It is the setting "steps" under "Render" and "Display" that made it possible to do this kind of small braids but it could also crash blender if set to high.

I thought if anyone is intrested, I prepared a blend file with the scalp and hairdo to study and use for free, CC0 to make it extra easy.

Edit 2018-02-12
Removed the blend-file as a new better version is uploaded here http://www.makehumancommunity.org/conte ... h_bun.html
End edit
Last edited by Mindfront on Mon Feb 12, 2018 10:35 pm, edited 1 time in total.
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