Poll

What option do you prefer to control hair highlights size?

Glossiness (currently used, also behaves similarly to CoronaMtl)
Roughness (usually hair shaders/materials use roughness instead of glossiness)

Author Topic: 1.7 - Hair shader playground and feedback  (Read 18254 times)

2017-07-07, 13:35:42
Reply #15

Ludvik Koutny

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Shouldn't rendering as planes VS cylinders be considered per object in scene, not globally? :)

2017-07-09, 23:12:09
Reply #16

Bigguns

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I second that Rawalanche ^^ ** same thing for the tesselation, like facial hairs they are super short, I don't need them to be as tesselated as the long hairs etc. I guess it can optimise RAM that way and render time as well .
« Last Edit: 2017-07-10, 00:34:40 by Bigguns »

2017-07-10, 11:03:10
Reply #17

Ondra

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ok, lets end the broscience here ;)

I did tests on the biggun's hair model, with 65k strands. Tried different embree subdiv settings, from 1 to 16. Results:

memory usage was always the same. Subdiv settings are applied only during traversal

Performance, in Mrays/s:
Subdiv  1: 5.6
Subdiv 4: 5.2
Subdiv 8: 5.1
Subdiv 16: 4.2

So only going into extremes - single subdiv, or 16 subdivs - have some effect. I am tempted to increase the default subdiv to 8, as there is no peformance penalty - remember that the scene was JUST the haircut, nothing else - with other geometry, the impact would be negligible

Rendering is magic.
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2017-07-10, 21:35:20
Reply #18

ylucic

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Damn...those came out a bit "Trumpy" :S
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2017-07-11, 02:58:28
Reply #19

cecofuli

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Ok, CoronaHairMtl now works with H&F.
But, is it normal, when I change some CoronaHairMtl (Diffuse Color, for example) I need to wait 10 second for the IR update?
It looks like Corona needs to rebuilt the hairs geometry structure, every time. 
It's very difficult to "play" with CoronaHairMtl in IR, because every shading change is so slow.

And, if I change the CoromaHairMtl opacity value (from 1 to 0.9, for example) I have ridiculous Rays/s speed (from 2 million to 100.000)
« Last Edit: 2017-07-11, 03:15:34 by cecofuli »

2017-07-11, 09:35:32
Reply #20

martinsik

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I have added a new poll that concerns how you control hair highlights size in CoronaHairMtl, please vote if this is important to you :)

2017-07-11, 09:39:00
Reply #21

martinsik

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looks like a fun material to play with, is highlight shift the same as anisotropy reflections?
Highlight shift can be though of as some sort of uniform bump mapping. In other words the normal is shifted by several degrees. This effect is here to simulate real hair fiber scales as seen on the image

2017-07-11, 09:42:32
Reply #22

martinsik

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Ok, CoronaHairMtl now works with H&F.
But, is it normal, when I change some CoronaHairMtl (Diffuse Color, for example) I need to wait 10 second for the IR update?
It looks like Corona needs to rebuilt the hairs geometry structure, every time. 
It's very difficult to "play" with CoronaHairMtl in IR, because every shading change is so slow.
In order to render Hair&Fur, all the hairs are first dump from 3ds max to a file and then loaded by Corona, that can take a pretty long time.

And, if I change the CoromaHairMtl opacity value (from 1 to 0.9, for example) I have ridiculous Rays/s speed (from 2 million to 100.000)
Yes, we are aware of this issue and will work on it. For now I recommend using opacity equal to 1 (it is also more physically correct).

2017-07-11, 14:14:23
Reply #23

cecofuli

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Thank you , Martin.
Maybe will we have some improvement about IR and H&F speed in the next release?
Or is it impossible, because 3ds max?

2017-07-11, 15:24:58
Reply #24

martinsik

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Maybe will we have some improvement about IR and H&F speed in the next release?
Or is it impossible, because 3ds max?
Unfortunately this is a limitation of Hair&Fur itself :(

2017-07-11, 16:26:01
Reply #25

romullus

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I like it CoronaHair very much. Never had chance to play with hair rendering much, so it's maybe good time to start doing it now :]
I'm not Corona Team member! Everything i say, is my personal opinion only. Render Legion does not endorse my words nor actions.

2017-07-11, 20:10:02
Reply #26

Fluss

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I'm starting some tests with the new hair shader. It seems to be quite slow. I've plugged the same map in both hair and diffuse color, everything else is set to defaults.

edit: dual xeon 2683 v3 (28 cores / 56 threads) @ 2.5GHz
« Last Edit: 2017-07-11, 21:45:18 by Fluss »

2017-07-11, 21:26:03
Reply #27

Bigguns

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I'm starting some tests with the new hair shader. It seems to be quite slow. I've plugged the same map in both hair and diffuse color, everything else is set to defaults.

It's certainly not as fast as the corona Mtl, wich is normal, since hairs is a particular material and this one is really accurate high quality material wich produce great result. It's like a skin shader, these shaders are never fast .. or if they are.. they are not accurate and look super fake. You can't have the butter and the money of the butter as we say haha :)

2017-07-11, 21:41:15
Reply #28

Fluss

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Yes I know that. But 490 000 rays/s on a dual xeon 2683 v3 (so 28 cores / 56 threads), on approx. 1200x900px is really really slow.

2017-07-11, 22:12:01
Reply #29

Ludvik Koutny

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Yes I know that. But 490 000 rays/s on a dual xeon 2683 v3 (so 28 cores / 56 threads), on approx. 1200x900px is really really slow.
Make sure you are rendering hair as planes, not cylinders, and definitely make sure you are not using any opacity mapping. These two things can slow rendering down extremely.