Actually the problem seems to occur only with one of the three scenes that I am testing: http://pasteall.org/blend/index.php?id=49754
Sorry for the bad hairstyle and probably not optimized hair particles configuration
It looks like this with build 2018-05-28, baad410a5c5 (the node had roughnessU, roughnessV items):
EDIT:
Wait … The HDRi seems not to be illuminating with the same intensity in any object in new build. Maybe the problem is not with Principled Hair. I will continue investigating later. Maybe my own compilation of Blender does not work correctly, I’m going to try that build you shared.
HDRI? Lukas changed the sampling code a bit, which resulted in some .blends getting no HDRI lighting samples. This is the case of the .blend you shared.
Go to World -> Settings -> Surface and turn on “Sampling method” (it is “None” in your blend, which is a symptom of this change).
What is problematic hair setup is small tiny hairs.
Like a realistic skin of a horse, tiny hairs but an enormous amount of them.
Which behaves a bit more like a 2d surface, i’ve used the velvet shader surface in the past. With lots of hairs on it, but the effect of a horse skin is difficult.
Maybe a shader that uses its 2D surface as top of hair pins and extend it a bit, like the proportional to distance based geometric data in some bump methods not particle based, but a special type of bump shader method
I don’t know why but in real size (40 to 100 microns) the hair is melted into a mass without details like molten resin. I have to put them at 300 micron to hope to have details.With mélanine or color direct by default same résult
Hi,
Sorry i am still very noob in blender but I am looking to see what can be done with the hair shaders in Blender and came across this post. Very interesting.
I just wanted to show you what can be done with Glint and Glitter. My friend Luc Bégin is doing some test for a new hair shader for V-Ray and he posted some pics on Facebook:
According to the paper (and my own experience), this shader needs at least 512 samples to have decent results, although you can get away with as little as 64 if you use denoising.
Increasing the number of glossy samples/bounces may help, too.
If you still get bad results, could you attach an example .blend here with the hair set to 100 microns for me to have a look at?
I’ve been adjusting the existing tests for the new shader, and it works nicely with 256 samples or higher. 512 samples or higher is needed if the hair is lightly colored or if it’s too thin (e.g. low Tip values).
Also make sure that:
if using Branched Path Tracing, Glossy samples should be in the range bove
if you control light path bounces, set Glossy to 4+
You can get away with ~2-4x less samples with the Denoiser; it is especially useful when using thin hair.
As regards the geometry, it works with any type of geometry but triangles (known Blender bug T43625). Set Thick for best results.
This week I don’t have many news as regards features. However, during the weekend I updated the Blender manual with new pages about the shader. I’ve also ported the existing hair Gtest suit to the new shader (this hasn’t been uploaded to SVN for obvious reasons).
Let me know if you’d like any changes in wording, explanations, etc. and I’ll make them ASAP. I still have to prepare images for explaining the different parameters.
The model being worked on as part of the google summer of code is more energy conserving. It sounds like maybe he was going to charge money for his node-group before development started on this.
Yeah, I thought about it since I put a lot of work into it. But figured it was something the community needed for free I’m excited to see how this new BSDF will handle hair.
Tomorrow we should be landing the shader code in master.
As for the requested documentations, they’re already available as of now in the Blender manual.
I’ve taken care to explain stuff as clearly as possible, and I’ve added charts for just about every prop, with the model provided by @ChrisWillC (ty for the contribution!)
I’m excited to see how this new BSDF will handle hair.
