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Really good particle hair tutorial for cycles

PostPosted: Tue Aug 16, 2016 9:37 am
by joepal
http://www.blendernation.com/2016/08/09 ... -tutorial/

This actually made me understand why my previous attempts at making hair usually ended up looking like haystacks. :-)

Re: Really good particle hair tutorial for cycles

PostPosted: Tue Aug 16, 2016 2:50 pm
by wolgade
joepal wrote:This actually made me understand why my previous attempts at making hair usually ended up looking like haystacks. :-)

Would you make a tutorial on how to create haystacks in Blender? :lol:

Seriously: These two tutorials are exactly the needle in the haystack, the missing link. They tell you what other tutorials don't tell you. Thanks for the link. Now I also need reference images.

I would like to add another link to a cycles hair tutorial you most probably already know. http://www.blenderguru.com/tutorials/how-to-render-hair-with-cycles/ is a bit outdated today and it only deals with materials and render settings. Some stuff changed in the mean time, but it explaines some settings very detailed. Not the usual "set this to 0.02", but what it does and how. It especially explaines the shape setting and tells you never to use solid colours for hair, but a texture. (There's no such thing as a solid colour in real world. Real world is noisy.)

Another interesting thing I discovered a few weeks back is https://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/Objects/HairNet. This addon converts meshes to particles. I gave it a try with the long hair that ships with MH, more precisely the top layer of strands.
mesh.jpg

It looks quite promising when rendered.
render.jpg

Ignore the fireflies in the image. Even this quality took more than 30 minutes. Completely OT: Can GPU rendering now be used for particles and if so, is it faster than CPU?

Re: Really good particle hair tutorial for cycles

PostPosted: Tue Aug 16, 2016 5:15 pm
by loki1950
Can GPU rendering now be used for particles and if so, is it faster than CPU?


Yes really depends on how many CUDA cores for the speed of rendering have't tried particle hair with my new box yet but I should see an improvement does the BMW benchmark but no particle systems in that blend file'

Enjoy the Choice :)

Re: Really good particle hair tutorial for cycles

PostPosted: Tue Aug 16, 2016 7:21 pm
by joepal
wolgade wrote:This addon converts meshes to particles.


That is so cool. :-)

wolgade wrote:Completely OT: Can GPU rendering now be used for particles and if so, is it faster than CPU?


Yes, and yes. On my dual GTX980 setup, render times are actually acceptable even for particle systems.

The downside with particles (and with SSS) is that you risk running out of graphics card memory (which is what is used by CUDA), so for more elaborate scenes you might have to fall back to CPU rendering.

Re: Really good particle hair tutorial for cycles

PostPosted: Tue Aug 16, 2016 7:36 pm
by joepal
My first experiment with the hairnet addon was not entirely successful :-)

hair_addon.png

Re: Really good particle hair tutorial for cycles

PostPosted: Wed Aug 17, 2016 11:25 am
by wolgade
joepal wrote:My first experiment with the hairnet addon was not entirely successful :-)

That depends on what you intended to do. You can always say that you wanted the result this way. :D

Seriously, this addon is far from being bullet proof. Make sure you have scale, rotation and location (?) applied. All strand meshes must have the same number of subdivisions. The root of your strand must be marked as a seam.

This one
no.jpg
no.jpg (3.76 KiB) Viewed 6571 times

will not work as a strand. You need at least one subdivision.

This one
yes.jpg
yes.jpg (4.11 KiB) Viewed 6571 times

will work.

I had a more detailed documentation for this plugin, but somehow I forgot to bookmark it.

Edit: Did you watch this: https://www.youtube.com/watch?v=Lr86lIXJCZQ? The video is linked in the Blender wiki. A brief look at this video gives me an impression on what you might have done wrong. After running the script you must change to particle edit mode and touch all particles. This can be done with a comb at almost no strength. Without this step your particles will have their default orientation. Your image looks like exactly this happened.

Re: Really good particle hair tutorial for cycles

PostPosted: Wed Aug 17, 2016 1:17 pm
by SaltyCowdawg
wolgade wrote:

Seriously, this addon is far from being bullet proof.



yah.. that's been my observation as well.



wolgade wrote:
I had a more detailed documentation for this plugin, but somehow I forgot to bookmark it.



If you ever find that bookmark let me know. I've experimented with this plugin a number of times with varying levels of success. Your post just told me a couple of things that I may have overlooked randomly in the past.

Re: Really good particle hair tutorial for cycles

PostPosted: Wed Aug 17, 2016 2:01 pm
by wolgade
The things I added to my post resulted from watching the linked video again. It includes some important information you don't find in the written documentation. Probably this is the more detailed documentation I remembered. Anyway, I had a lot of trial and error before I got results. The worst thing to do is to forget to touch your particles in particle edit mode. Once you render you loose all your work which is really frustrating. The basic Blender rule is very true for this plugin: Save your work often and save it under a different file name before you do something that can't be easiely undone.

Re: Really good particle hair tutorial for cycles

PostPosted: Wed Aug 17, 2016 3:54 pm
by loki1950
ve your work often and save it under a different file name before you do something that can't be easiely undone.


You can use blender's incremental file names feature automates that :D

Enjoy the Choice :)

Re: Really good particle hair tutorial for cycles

PostPosted: Mon Aug 22, 2016 3:11 pm
by wolgade
And yet another way to convert meshes to particles you might not be aware of:

As posted in the MHX2 section, Thomas Larsson moved his MHX2 repo. If you follow the link to his blog (http://diffeomorphic.blogspot.de/), you'll learn that he wrote an importer for DAZ stuff. DAZ characters use mesh hair so he included an option to convert meshes to particles. This function is not limited to DAZ stuff, but can of course be used with any mesh you like. Ok, not any mesh you like. The DAZ importer makes some asumptions that have to be met for usefull output. Even if don't own any DAZ item his addon is worth looking at. The relevant documentation for the hair options can be found here: http://diffeomorphic.blogspot.de/p/advanced-setup-panel.html