Re: realistic hair shading SI-MR

[Christian Keller]

It's a long time ago that I did hair with mr, Arnold makes that a breeze now. 
But I did that always with the rasterizer. If the hair is not to long you could 
bake the final gathering into a texture and use that to mix it into the 
shading, which gives you a nice look without too much rendering time.
Cheers
Chris 

Von meinem iPhone gesendet

> Am 07.12.2014 um 09:17 schrieb pete...@skynet.be:
> 
> Thanks Matt -
> interesting - I've come across a custom hair normals shader that was giving a 
> better, more "tube" or "cone" feel - that gave some more "presence" to the 
> hairs. (More so at close up) - and in my understanding the flat vs 
> cylindrical normals was the explanation. But I stand corrected.
> Still I've found the crosswise gradient as a bump useful on hair (and grass) 
> to give them a less flat feel.
> 
> You're very right of course that flat ribbon is much more geometry efficient 
> than cylinder - with all the memory advantages - but when 3Delight renders 
> those beautiful hair 'tubes' without any geometric artifacts, much more 
> convincing looking and much faster and at a fraction of the memory overhead - 
> it's hard to complement MR on its very efficient choice of the flat ribbon. 
> (apples and oranges, I know)
> 
> Yes, I did my own digging in rendersettings for hair on Barnyard. Having a 
> screenful of unique characters, each with several patches of hair, with 
> wildly different styles and requirements, 8 years ago, on MR, with 
> requirement for a plethora of lights in the scene, all of them with 
> (soft)shadows. The default settings fall down quick, as in: results not good 
> enough plus too slow, but there is a lot to be got out MR in that respect 
> yet. (which was the main reason for my reply to OP) I recall rasterizer and 
> shadowmaps as two main ones for making it look better (also filtering and 
> sampling ofcourse) - and then all those little parameters to get the 
> rendertimes down. BSP, raydepth, and careful use of partitions and visibility 
> settings!
> And from that production (and others after) I've never had the feeling of 
> hair being a real bottleneck for lighting. Particles and effects much more so 
> in those pre-pre-ICE days.
> 
> Cheers
> 
> -Original Message- From: Matt Lind
> Sent: Sunday, December 07, 2014 2:03 AM
> To: softimage@listproc.autodesk.com
> Subject: realistic hair shading SI-MR
> 
> @Peter
> 
> MR hair geometry is flat ribbon, but the normal is computed from a virtual
> cylinder like a normal map with full control over shaft radius and taper
> along the length.  For most practical purposes it should create the desired
> look.  Using the utility shaders (math/lookup nodes) available in the
> rendertree, you can read hair UV coords and surface normal yourself if you
> want to shade them differently than the provided hair shaders.  Mental ray
> stores hair information in the state which can be accessed by any shader
> which cares to dig into that information.
> 
> The reason for flat ribbon is to allow hair to be represented as physical
> geometry which can be styled and groomed, respond to dynamics, and use
> material/texture shaders for shading while keeping memory consumption
> low/reasonable (representing hair as geometry is hugely expensive).  Mental
> ray does offer true cylinder hair, but to get cylinder hair would require
> the hair shader to be implemented as a volume shader (which would have it's
> own set of issues).  I believe that was how the original softimage hair
> shader from 10 years ago was implemented.  It rendered hair convincingly for
> the basics such as highlights, but most people didn't like it because as a
> volume shader it did not permit styling and grooming (or at least not much
> control over it), and rendered quite slow with frequent crashing as mental
> ray volumes can be a bit finicky.
> 
> I experimented with hair rendering in mental ray for Barnyard all those
> years ago.  From a purely technical point of view, writing shaders for hair
> isn't too hard - it's just standard material/texture shader with additional
> metadata for the hair.  The key to getting results is being smart with your
> render settings.  You must be stringent on ray depth, recursion, shadow
> type, memory limits, and so on.  Setting them too generously will make your
> render times go through the roof as you're telling mental ray to wander and
> find things to do which probably aren't necessary.  the default render
> settings in Softimage are probably too generous for hair.
> 
> 
> Matt
> 

Re: realistic hair shading SI-MR

[Leendert A. Hartog]

Well, I did a lot of reading on the subject (fascinating stuff) and ran 
some tests (with MR and 3delight both) and have come to the conclusion 
there just aren’t enough hours in my (hobbyist) days to ever get this 
right. In conclusion: my intended image will get the trusted NPR look. 
Thank you all, though, for helping to clear this up.

;)

Greetz
Leendert

--

Leendert A. Hartog AKA Hirazi Blue
Administrator NOT the owner of si-community.com

Re: realistic hair shading SI-MR

[Jason S]

  
  
From the 2015 "what's
new" doc
  
  Support for mental ray 3.12
   Softimage now supports the NVIDIA
mental ray renderer version 3.12
  
  So one down for GI, hopefully eventually with Motion blur.. plus
  also : Visibility (cutout opacity) 
  
  which would also be too bad if you cant have alpha cutouts (?) )
  
  Nevertheless Wohoo! :)
  
  and that means the your new hair shader should also be in there
  Hirazi!
  
  
  On 12/08/14 11:29, Jason S wrote:


  
  Sorry, also a Link :)
https://elementalray.wordpress.com/2014/07/29/new-gi-prototype-quick-start/

On 12/08/14 11:23, Jason S wrote:
  
  


  Or is it already ver. 3.12 of MR (like Maya 2015) that is
in SI 2015?

And by looking at the some of the new GI prototype
limitations, 
I would hope that particularly the first point in that list
would be addressed before the last SI SPx
  
  .. but for it to at-all be there would be already
something, even in CPU mode, it's supposed to be fairly fast
and usable.
Ah man.
  
  As such there are some limitations
to know about in this prototype:
   
  
Motion blur not supported
Lens shaders not supported
Hair is tessellated
Visibility (cutout opacity) not
  supported
Specular interaction currently
  handled by Final Gather
  
  
  
  On 12/08/14 11:07, Jason S wrote:


  
  IMO Apart from from Hair, I would
really hope, and I think it would be important that SI would
include at least one of these latest versions of MentalRay
(meaning before the last SI update)
**for there to be an actually usable GI solution
(performance-wise & artifact-free-in-animation-wise)
  in one of the last official Softimage releases
  out-of-the-box **.

Because since July (?) has there been (finally) this first
in MentalRay since forever. (!)

Even if new features would be unsupported, without even a
need for them to be exposed,  
(then accessible at least through string options and perhaps
addons)

I would find it really silly if it didn't make it in, while
MR versions with perhaps early but functional new GI methods
has been around for a bit already, 
and while SI is technically still supported.
(mumbling to myself ... please please please!)

On 12/07/14 15:07, Anto Matkovic wrote:
  
  

  Well, a
  lot of people got it to work. But it was a practice,
  to do not share such thing with 'everyone'. Yeah I
  also have one, created by masters, but I'm unable to
  share it. As far as I know, Modo 601 and Mantra from
  Houdini 13, are the first 3d apps, having this dual
  thing, right out of the box. Red Shift too, if I
  understood correctly. So entire Renderman
  mystification became fairly irrelevant, today.

  
  

  
  From: Rob
  Chapman 
  To: Anto
  Matkovic ;
  "softimage@listproc.autodesk.com"
  
  
  Sent:
  Sunday, December 7, 2014 6:54 PM
      Subject:
  Re: realistic hair shading SI-MR
 
  

  
re: renderman dual scattering in
  softimage, appears someone has it working in
  3delight
  
  
  https://vimeo.com/19108621
  
  
  
  also
someone at mental ray did implement a dual
scattering shader for 3.12 - see here for
details under human hair, not sure if its
included in 2015 or not look for basehair
  
  
  best
  
  
  Rob
  
  
  
  
  

  

  

  

  
  


  
  


  

Re: realistic hair shading SI-MR

[David Rivera]

@ROB, I can´t get to the link where you mention: "also someone at mental ray 
did implement a dual scattering shader for 3.12 - see here for details under 
human hair, not sure if its included in 2015 or not look for basehair". Could 
you please help me out with the link? Susantos made that video some years ago. 
I remember opening Vimeo, and Boom! I was researching for dual scattering, 
until I found Imahn Saldeghi´s Disney paper. I tried to replicate it on mental 
ray, some of it went well...but not totally. :)
Thanks. David Rivera
3D Compositor/Animator
LinkedIN
Behance
VFX Reel
  From: Anto Matkovic 
 To: "softimage@listproc.autodesk.com"  
 Sent: Sunday, December 7, 2014 3:07 PM
 Subject: Re: realistic hair shading SI-MR
   
Well, a lot of people got it to work. But it was a practice, to do not share 
such thing with 'everyone'. Yeah I also have one, created by masters, but I'm 
unable to share it. As far as I know, Modo 601 and Mantra from Houdini 13, are 
the first 3d apps, having this dual thing, right out of the box. Red Shift too, 
if I understood correctly. So entire Renderman mystification became fairly 
irrelevant, today.

  From: Rob Chapman 
 To: Anto Matkovic ; "softimage@listproc.autodesk.com" 
 
 Sent: Sunday, December 7, 2014 6:54 PM
 Subject: Re: realistic hair shading SI-MR
   
re: renderman dual scattering in softimage, appears someone has it working in 
3delight
https://vimeo.com/19108621

also someone at mental ray did implement a dual scattering shader for 3.12 - 
see here for details under human hair, not sure if its included in 2015 or not 
look for basehair
best
Rob


   

  

Re: realistic hair shading SI-MR

[Jason S]

  
  
Sorry, also a Link :)
  https://elementalray.wordpress.com/2014/07/29/new-gi-prototype-quick-start/
  
  On 12/08/14 11:23, Jason S wrote:


  
  
Or is it already ver. 3.12 of MR (like Maya 2015) that is in
  SI 2015?
  
  And by looking at the some of the new GI prototype
  limitations, 
  I would hope that particularly the first point in that list
  would be addressed before the last SI SPx

.. but for it to at-all be there would be already something,
  even in CPU mode, it's supposed to be fairly fast and usable.
  Ah man.

As such there are some limitations
  to know about in this prototype:
 

  Motion blur not supported
  Lens shaders not supported
  Hair is tessellated
  Visibility (cutout opacity) not
supported
  Specular interaction currently
handled by Final Gather



On 12/08/14 11:07, Jason S wrote:
  
  

IMO Apart from from Hair, I would
  really hope, and I think it would be important that SI would
  include at least one of these latest versions of MentalRay
  (meaning before the last SI update)
  **for there to be an actually usable GI solution
  (performance-wise & artifact-free-in-animation-wise) in
one of the last official Softimage releases
out-of-the-box **.
  
  Because since July (?) has there been (finally) this first in
  MentalRay since forever. (!)
  
  Even if new features would be unsupported, without even a need
  for them to be exposed,  
  (then accessible at least through string options and perhaps
  addons)
  
  I would find it really silly if it didn't make it in, while MR
  versions with perhaps early but functional new GI methods has
  been around for a bit already, 
  and while SI is technically still supported.
  (mumbling to myself ... please please please!)
  
  On 12/07/14 15:07, Anto Matkovic wrote:


  
Well, a
lot of people got it to work. But it was a practice, to
do not share such thing with 'everyone'. Yeah I also
have one, created by masters, but I'm unable to share
it. As far as I know, Modo 601 and Mantra from Houdini
13, are the first 3d apps, having this dual thing, right
out of the box. Red Shift too, if I understood
correctly. So entire Renderman mystification became
fairly irrelevant, today.
  


  

From: Rob
Chapman 
To: Anto
Matkovic ;
"softimage@listproc.autodesk.com"


Sent:
Sunday, December 7, 2014 6:54 PM
    Subject:
            Re: realistic hair shading SI-MR
   

  

  re: renderman dual scattering in
softimage, appears someone has it working in
3delight


https://vimeo.com/19108621



also
  someone at mental ray did implement a dual
  scattering shader for 3.12 - see here for
  details under human hair, not sure if its
  included in 2015 or not look for basehair


best


Rob





  

  

  

  


  
  


  

Re: realistic hair shading SI-MR

[Jason S]

  
  

  Or is it already ver. 3.12 of MR (like Maya 2015) that is in SI
2015?

And by looking at the some of the new GI prototype limitations,

I would hope that particularly the first point in that list
would be addressed before the last SI SPx
  
  .. but for it to at-all be there would be already something,
even in CPU mode, it's supposed to be fairly fast and usable.
Ah man.
  
  As such there are some limitations to
know about in this prototype:
  

  
Motion blur not supported
Lens shaders not supported
Hair is tessellated
Visibility (cutout opacity) not
  supported
Specular interaction currently
  handled by Final Gather
  
  
  
  On 12/08/14 11:07, Jason S wrote:


  
  IMO Apart from from Hair, I would
really hope, and I think it would be important that SI would
include at least one of these latest versions of MentalRay
(meaning before the last SI update)
**for there to be an actually usable GI solution
(performance-wise & artifact-free-in-animation-wise) in
  one of the last official Softimage releases
  out-of-the-box **.

Because since July (?) has there been (finally) this first in
MentalRay since forever. (!)

Even if new features would be unsupported, without even a need
for them to be exposed,  
(then accessible at least through string options and perhaps
addons)

I would find it really silly if it didn't make it in, while MR
versions with perhaps early but functional new GI methods has
been around for a bit already, 
and while SI is technically still supported.
(mumbling to myself ... please please please!)

On 12/07/14 15:07, Anto Matkovic wrote:
  
  

  Well, a lot of people
  got it to work. But it was a practice, to do not share
  such thing with 'everyone'. Yeah I also have one, created
  by masters, but I'm unable to share it. As far as I know,
  Modo 601 and Mantra from Houdini 13, are the first 3d
  apps, having this dual thing, right out of the box. Red
  Shift too, if I understood correctly. So entire Renderman
  mystification became fairly irrelevant, today.

  
  

  
  From: Rob
  Chapman 
  To: Anto
  Matkovic ;
  "softimage@listproc.autodesk.com"
  
  
  Sent:
  Sunday, December 7, 2014 6:54 PM
  Subject: Re:
          realistic hair shading SI-MR
 
  

  
re:

  renderman dual scattering in softimage, appears
  someone has it working in 3delight
  
  
  https://vimeo.com/19108621
  
  
  
  also
someone at mental ray did implement a dual
scattering shader for 3.12 - see here for
details under human hair, not sure if its
included in 2015 or not look for basehair
  
  
  best
  
  
  Rob
  
  
  
  
  

  

  

  

  
  


  

Re: realistic hair shading SI-MR

[Jason S]

  
  
IMO Apart from from Hair, I would
  really hope, and I think it would be important that SI would
  include at least one of these latest versions of MentalRay
  (meaning before the last SI update)
  **for there to be an actually usable GI solution
  (performance-wise & artifact-free-in-animation-wise) in one
of the last official Softimage releases out-of-the-box
  **.
  
  Because since July (?) has there been (finally) this first in
  MentalRay since forever. (!)
  
  Even if new features would be unsupported, without even a need for
  them to be exposed,  
  (then accessible at least through string options and perhaps
  addons)
  
  I would find it really silly if it didn't make it in, while MR
  versions with perhaps early but functional new GI methods has been
  around for a bit already, 
  and while SI is technically still supported.
  (mumbling to myself ... please please please!)
  
  On 12/07/14 15:07, Anto Matkovic wrote:


  
Well, a lot of people
got it to work. But it was a practice, to do not share such
thing with 'everyone'. Yeah I also have one, created by
masters, but I'm unable to share it. As far as I know, Modo
601 and Mantra from Houdini 13, are the first 3d apps,
having this dual thing, right out of the box. Red Shift too,
if I understood correctly. So entire Renderman mystification
became fairly irrelevant, today.
  


  

From: Rob
Chapman 
To: Anto
Matkovic ;
"softimage@listproc.autodesk.com"
 
Sent: Sunday,
December 7, 2014 6:54 PM
    Subject: Re:
        realistic hair shading SI-MR
   

  

  re:
renderman dual scattering in softimage, appears
someone has it working in 3delight


https://vimeo.com/19108621



also
  someone at mental ray did implement a dual
  scattering shader for 3.12 - see here for details
  under human hair, not sure if its included in 2015
  or not look for basehair


best


Rob





  

  

  

  


  

Re: realistic hair shading SI-MR

[Anto Matkovic]

Well, a lot of people got it to work. But it was a practice, to do not share 
such thing with 'everyone'. Yeah I also have one, created by masters, but I'm 
unable to share it. As far as I know, Modo 601 and Mantra from Houdini 13, are 
the first 3d apps, having this dual thing, right out of the box. Red Shift too, 
if I understood correctly. So entire Renderman mystification became fairly 
irrelevant, today.

  From: Rob Chapman 
 To: Anto Matkovic ; "softimage@listproc.autodesk.com" 
 
 Sent: Sunday, December 7, 2014 6:54 PM
 Subject: Re: realistic hair shading SI-MR
   
re: renderman dual scattering in softimage, appears someone has it working in 
3delight
https://vimeo.com/19108621

also someone at mental ray did implement a dual scattering shader for 3.12 - 
see here for details under human hair, not sure if its included in 2015 or not 
look for basehair
best
Rob


   

Re: realistic hair shading SI-MR

[Rob Chapman]

http://docs.autodesk.com/MENTALRAY/2015/JPN/mental-ray-help/files/manual/upgrading312.html

the link would help..

On 7 December 2014 at 17:54, Rob Chapman  wrote:

> re: renderman dual scattering in softimage, appears someone has it working
> in 3delight
>
> https://vimeo.com/19108621
>
> also someone at mental ray did implement a dual scattering shader for 3.12
> - see here for details under human hair, not sure if its included in 2015
> or not look for basehair
>
> best
>
> Rob
>
>
>
> On 6 December 2014 at 20:53, Anto Matkovic  wrote:
>
>> Custom Rman shaders available around, they are only 'core' part. Even you
>> can apply them as 3dl property, you can't get proper point-based GI in most
>> cases, especially not path traced GI, MIS an so on.Custom color mapping,
>> coming from SI, won't work too, of course.
>> All of free Marschner Rman shaders are single scatter model ( single
>> scatter = Muh Hair). Implementation of fancy dual scattering model, this
>> seems to belong to additional coding in RMan and 3delight, not a plain RSL
>> - so, unless Pixar will have a mercy, don't believe you'll be able to get
>> the dual thing in upcoming Renderman, too.  Maya or SI, doesn't matter.
>>
>> Perhaps the shortest path for one man band and single machine, it is to
>> just hack the RSL of 3dl emulation of SI hair shader, add code for shifted
>> highlight, map the parameter to something unused in PPG ( 'flat light' for
>> example), use two or three opaque shaders in render tree, pass the result
>> through constant shader for transparency and GI, at the end. 3delight is
>> quite good in optimizing the structure of this kind. But this is really a
>> hack.
>>
>> Regarding Mr, old Muh Hair definitively won't work, but there is a chance
>> to get working version of p_HairTK, somewhere. Or, maybe, working
>> implementation of built in 'basehair' in latest Mental Ray 3.12. Both are
>> single scatter model, but,  still more than out of the box solution.
>>
>>   --
>>  *From:* Leendert A. Hartog 
>> *To:* softimage@listproc.autodesk.com
>> *Sent:* Saturday, December 6, 2014 1:55 PM
>> *Subject:* Re: realistic hair shading SI-MR
>>
>> Any chance of achieving better results with 3delight (as it's so "budget
>> friendly"), possibly with custom shaders?
>>
>>
>>
>>
>> Greetz
>> Leendert
>>
>> --
>>
>> Leendert A. Hartog AKA Hirazi Blue
>> Administrator NOT the owner of si-community.com
>>
>>
>>
>>
>

Re: realistic hair shading SI-MR

[Rob Chapman]

re: renderman dual scattering in softimage, appears someone has it working
in 3delight

https://vimeo.com/19108621

also someone at mental ray did implement a dual scattering shader for 3.12
- see here for details under human hair, not sure if its included in 2015
or not look for basehair

best

Rob



On 6 December 2014 at 20:53, Anto Matkovic  wrote:

> Custom Rman shaders available around, they are only 'core' part. Even you
> can apply them as 3dl property, you can't get proper point-based GI in most
> cases, especially not path traced GI, MIS an so on.Custom color mapping,
> coming from SI, won't work too, of course.
> All of free Marschner Rman shaders are single scatter model ( single
> scatter = Muh Hair). Implementation of fancy dual scattering model, this
> seems to belong to additional coding in RMan and 3delight, not a plain RSL
> - so, unless Pixar will have a mercy, don't believe you'll be able to get
> the dual thing in upcoming Renderman, too.  Maya or SI, doesn't matter.
>
> Perhaps the shortest path for one man band and single machine, it is to
> just hack the RSL of 3dl emulation of SI hair shader, add code for shifted
> highlight, map the parameter to something unused in PPG ( 'flat light' for
> example), use two or three opaque shaders in render tree, pass the result
> through constant shader for transparency and GI, at the end. 3delight is
> quite good in optimizing the structure of this kind. But this is really a
> hack.
>
> Regarding Mr, old Muh Hair definitively won't work, but there is a chance
> to get working version of p_HairTK, somewhere. Or, maybe, working
> implementation of built in 'basehair' in latest Mental Ray 3.12. Both are
> single scatter model, but,  still more than out of the box solution.
>
>   --
>  *From:* Leendert A. Hartog 
> *To:* softimage@listproc.autodesk.com
> *Sent:* Saturday, December 6, 2014 1:55 PM
> *Subject:* Re: realistic hair shading SI-MR
>
> Any chance of achieving better results with 3delight (as it's so "budget
> friendly"), possibly with custom shaders?
>
>
>
>
> Greetz
> Leendert
>
> --
>
> Leendert A. Hartog AKA Hirazi Blue
> Administrator NOT the owner of si-community.com
>
>
>
>

Re: realistic hair shading SI-MR

[peter_b]

Thanks Matt -
interesting - I've come across a custom hair normals shader that was giving 
a better, more "tube" or "cone" feel - that gave some more "presence" to the 
hairs. (More so at close up) - and in my understanding the flat vs 
cylindrical normals was the explanation. But I stand corrected.
Still I've found the crosswise gradient as a bump useful on hair (and grass) 
to give them a less flat feel.


You're very right of course that flat ribbon is much more geometry efficient 
than cylinder - with all the memory advantages - but when 3Delight renders 
those beautiful hair 'tubes' without any geometric artifacts, much more 
convincing looking and much faster and at a fraction of the memory 
overhead - it's hard to complement MR on its very efficient choice of the 
flat ribbon. (apples and oranges, I know)


Yes, I did my own digging in rendersettings for hair on Barnyard. Having a 
screenful of unique characters, each with several patches of hair, with 
wildly different styles and requirements, 8 years ago, on MR, with 
requirement for a plethora of lights in the scene, all of them with 
(soft)shadows. The default settings fall down quick, as in: results not good 
enough plus too slow, but there is a lot to be got out MR in that respect 
yet. (which was the main reason for my reply to OP) I recall rasterizer and 
shadowmaps as two main ones for making it look better (also filtering and 
sampling ofcourse) - and then all those little parameters to get the 
rendertimes down. BSP, raydepth, and careful use of partitions and 
visibility settings!
And from that production (and others after) I've never had the feeling of 
hair being a real bottleneck for lighting. Particles and effects much more 
so in those pre-pre-ICE days.


Cheers

-Original Message- 
From: Matt Lind

Sent: Sunday, December 07, 2014 2:03 AM
To: softimage@listproc.autodesk.com
Subject: realistic hair shading SI-MR

@Peter

MR hair geometry is flat ribbon, but the normal is computed from a virtual
cylinder like a normal map with full control over shaft radius and taper
along the length.  For most practical purposes it should create the desired
look.  Using the utility shaders (math/lookup nodes) available in the
rendertree, you can read hair UV coords and surface normal yourself if you
want to shade them differently than the provided hair shaders.  Mental ray
stores hair information in the state which can be accessed by any shader
which cares to dig into that information.

The reason for flat ribbon is to allow hair to be represented as physical
geometry which can be styled and groomed, respond to dynamics, and use
material/texture shaders for shading while keeping memory consumption
low/reasonable (representing hair as geometry is hugely expensive).  Mental
ray does offer true cylinder hair, but to get cylinder hair would require
the hair shader to be implemented as a volume shader (which would have it's
own set of issues).  I believe that was how the original softimage hair
shader from 10 years ago was implemented.  It rendered hair convincingly for
the basics such as highlights, but most people didn't like it because as a
volume shader it did not permit styling and grooming (or at least not much
control over it), and rendered quite slow with frequent crashing as mental
ray volumes can be a bit finicky.

I experimented with hair rendering in mental ray for Barnyard all those
years ago.  From a purely technical point of view, writing shaders for hair
isn't too hard - it's just standard material/texture shader with additional
metadata for the hair.  The key to getting results is being smart with your
render settings.  You must be stringent on ray depth, recursion, shadow
type, memory limits, and so on.  Setting them too generously will make your
render times go through the roof as you're telling mental ray to wander and
find things to do which probably aren't necessary.  the default render
settings in Softimage are probably too generous for hair.


Matt

realistic hair shading SI-MR

[Matt Lind]

@Peter

MR hair geometry is flat ribbon, but the normal is computed from a virtual 
cylinder like a normal map with full control over shaft radius and taper 
along the length.  For most practical purposes it should create the desired 
look.  Using the utility shaders (math/lookup nodes) available in the 
rendertree, you can read hair UV coords and surface normal yourself if you 
want to shade them differently than the provided hair shaders.  Mental ray 
stores hair information in the state which can be accessed by any shader 
which cares to dig into that information.


The reason for flat ribbon is to allow hair to be represented as physical 
geometry which can be styled and groomed, respond to dynamics, and use 
material/texture shaders for shading while keeping memory consumption 
low/reasonable (representing hair as geometry is hugely expensive).  Mental 
ray does offer true cylinder hair, but to get cylinder hair would require 
the hair shader to be implemented as a volume shader (which would have it's 
own set of issues).  I believe that was how the original softimage hair 
shader from 10 years ago was implemented.  It rendered hair convincingly for 
the basics such as highlights, but most people didn't like it because as a 
volume shader it did not permit styling and grooming (or at least not much 
control over it), and rendered quite slow with frequent crashing as mental 
ray volumes can be a bit finicky.


I experimented with hair rendering in mental ray for Barnyard all those 
years ago.  From a purely technical point of view, writing shaders for hair 
isn't too hard - it's just standard material/texture shader with additional 
metadata for the hair.  The key to getting results is being smart with your 
render settings.  You must be stringent on ray depth, recursion, shadow 
type, memory limits, and so on.  Setting them too generously will make your 
render times go through the roof as you're telling mental ray to wander and 
find things to do which probably aren't necessary.  the default render 
settings in Softimage are probably too generous for hair.



Matt

Re: realistic hair shading SI-MR

[Anto Matkovic]

Custom Rman shaders available around, they are only 'core' part. Even you can 
apply them as 3dl property, you can't get proper point-based GI in most cases, 
especially not path traced GI, MIS an so on.Custom color mapping, coming from 
SI, won't work too, of course.All of free Marschner Rman shaders are single 
scatter model ( single scatter = Muh Hair). Implementation of fancy dual 
scattering model, this seems to belong to additional coding in RMan and 
3delight, not a plain RSL - so, unless Pixar will have a mercy, don't believe 
you'll be able to get the dual thing in upcoming Renderman, too.  Maya or SI, 
doesn't matter.

Perhaps the shortest path for one man band and single machine, it is to just 
hack the RSL of 3dl emulation of SI hair shader, add code for shifted 
highlight, map the parameter to something unused in PPG ( 'flat light' for 
example), use two or three opaque shaders in render tree, pass the result 
through constant shader for transparency and GI, at the end. 3delight is quite 
good in optimizing the structure of this kind. But this is really a hack.

Regarding Mr, old Muh Hair definitively won't work, but there is a chance to 
get working version of p_HairTK, somewhere. Or, maybe, working implementation 
of built in 'basehair' in latest Mental Ray 3.12. Both are single scatter 
model, but,  still more than out of the box solution.

  From: Leendert A. Hartog 
 To: softimage@listproc.autodesk.com 
 Sent: Saturday, December 6, 2014 1:55 PM
 Subject: Re: realistic hair shading SI-MR
   
Any chance of achieving better results with 3delight (as it's so "budget 
friendly"), possibly with custom shaders?



Greetz
Leendert

-- 

Leendert A. Hartog AKA Hirazi Blue
Administrator NOT the owner of si-community.com



  

Re: realistic hair shading SI-MR

[Angus Davidson]

The trick is you don¹t get the Data to Maya. You get it to a solid
dependable format that Maya (or whatever can read) In theory you can send
it to blender which is actually pretty decent for rendering and
compositing.


On 2014/12/06, 6:54 PM, "Leendert A. Hartog"  wrote:

>Oh, it's definitively worth looking into once it finally arrives.
>As a renderer I'll surely take it for a spin.
>Even if that means my return to Maya.
>But I somehow don't like having to get data from Softimage to Maya and
>vice versa.
>To most of you it must be second nature. To me it still has an touch of
>voodoo.
>
>Greetz
>Leendert
>
>-- 
>
>Leendert A. Hartog AKA Hirazi Blue
>Administrator NOT the owner of si-community.com
>

 

This communication is 
intended for the addressee only. It is confidential. If you have received this 
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are not necessarily the views and opinions of The University of the 
Witwatersrand, Johannesburg. All agreements between the University and 
outsiders are subject to South African Law unless the University agrees in 
writing to the contrary. 

Re: realistic hair shading SI-MR

[Leendert A. Hartog]

Oh, it's definitively worth looking into once it finally arrives.
As a renderer I'll surely take it for a spin.
Even if that means my return to Maya.
But I somehow don't like having to get data from Softimage to Maya and 
vice versa.
To most of you it must be second nature. To me it still has an touch of 
voodoo.


Greetz
Leendert

--

Leendert A. Hartog AKA Hirazi Blue
Administrator NOT the owner of si-community.com

Re: realistic hair shading SI-MR

[Angus Davidson]

True, But I am assuming that you can use softimage, for pretty much
everything, export to alembic, apply render man mats and render in Maya.

Part of the reason for the Renderman NC 19 is so that they can polish the
docs and examples for first time users. So worth having a look at.

You can do the same pipeline and render in the free version of Houdini as
well. For testing of course.

Kind regards

Angus



On 2014/12/06, 6:38 PM, "Leendert A. Hartog"  wrote:

>Worth pointing out in turn: that's Maya-only IIRC. :D
>
>Greetz
>Leendert
>
>-- 
>
>Leendert A. Hartog AKA Hirazi Blue
>Administrator NOT the owner of si-community.com
>

 

This communication is 
intended for the addressee only. It is confidential. If you have received this 
communication in error, please notify us immediately and destroy the original 
message. You may not copy or disseminate this communication without the 
permission of the University. Only authorised signatories are competent to 
enter into agreements on behalf of the University and recipients are thus 
advised that the content of this message may not be legally binding on the 
University and may contain the personal views and opinions of the author, which 
are not necessarily the views and opinions of The University of the 
Witwatersrand, Johannesburg. All agreements between the University and 
outsiders are subject to South African Law unless the University agrees in 
writing to the contrary. 

Re: realistic hair shading SI-MR

[Leendert A. Hartog]

Worth pointing out in turn: that's Maya-only IIRC. :D

Greetz
Leendert

--

Leendert A. Hartog AKA Hirazi Blue
Administrator NOT the owner of si-community.com

Re: realistic hair shading SI-MR

[Angus Davidson]

Worth pointing out that Renderman r19 will be free from early Jan for non
commercial work. I would suggest waiting a little bit for that .

Kind regards

Angus

On 2014/12/06, 5:33 PM, "Leendert A. Hartog"  wrote:

>Interesting. Will have a look. Thanks.
>
>Greetz
>Leendert
>
>-- 
>
>Leendert A. Hartog AKA Hirazi Blue
>Administrator NOT the owner of si-community.com
>

 

This communication is 
intended for the addressee only. It is confidential. If you have received this 
communication in error, please notify us immediately and destroy the original 
message. You may not copy or disseminate this communication without the 
permission of the University. Only authorised signatories are competent to 
enter into agreements on behalf of the University and recipients are thus 
advised that the content of this message may not be legally binding on the 
University and may contain the personal views and opinions of the author, which 
are not necessarily the views and opinions of The University of the 
Witwatersrand, Johannesburg. All agreements between the University and 
outsiders are subject to South African Law unless the University agrees in 
writing to the contrary. 

Re: realistic hair shading SI-MR

[Leendert A. Hartog]

Interesting. Will have a look. Thanks.

Greetz
Leendert

--

Leendert A. Hartog AKA Hirazi Blue
Administrator NOT the owner of si-community.com

Re: realistic hair shading SI-MR

[Andy Goehler]

Hey Leendert, look here:

http://www.3delight.com/en/modules/PunBB/viewtopic.php?id=2030 


Oldie but goodie. 


> On Dec 06, 2014, at 14:08, Leendert A. Hartog  wrote:
> 
> Thanks, I was just coming to the same conclusion... ;)
> In 3delight would the converted Softimage hair shaders suffice
> or would still have to look for some custom shader?
> 
> Greetz
> Leendert
> 
> -- 
> 
> Leendert A. Hartog AKA Hirazi Blue
> Administrator NOT the owner of si-community.com
> 

Re: realistic hair shading SI-MR

[Leendert A. Hartog]

Thanks, I was just coming to the same conclusion... ;)
In 3delight would the converted Softimage hair shaders suffice
or would still have to look for some custom shader?

Greetz
Leendert

--

Leendert A. Hartog AKA Hirazi Blue
Administrator NOT the owner of si-community.com

Re: realistic hair shading SI-MR

[peter_b]

well, if it's a financial issue - get 3delight. You can use it for free with 
some number-of-cores limitation, that still makes it awesome at a lot of 
things were MR isnt. Hair in particular being one of those.



For me, a huge issue with hair in XSI/MR is the normals. The hair primitive 
is done as a flat ribbon, for decent light interaction it should be a 
cylinder. (which is what 3delight does - or is it a cone? anyway not a flat 
ribbon)
You can have cylinder like normals with a custom shader (if you write it 
yourself it's 'free', if you have someone write it for you this could end up 
more expensive that a renderlicense - so that's not very feasible).


You can make things a bit better (just a bit) with a gradient on the hair 
(black white black - crosswise) as a bump. This will give you somewhat 
better normals. But you will need very decent sampling for this to really 
matter - and decent sampling with hair in MR is going to be painful.
There's a couple of (out of the box) things that can improve hair rendering 
in MR - shadowmapped lights and  the rasterizer in particular jump to mind. 
But don’t expect miracles either.

...


-Original Message- 
From: Leendert A. Hartog

Sent: Saturday, December 06, 2014 1:16 PM
To: softimage@listproc.autodesk.com
Subject: Re: realistic hair shading SI-MR

Okay, this was intended as a thread with a serious question about hair
shading in MR,
but it's turned into a Redshift infomercial. ;)
If I had the funds at my disposal, I already would have bought it.
Ah, well, a bald human head definitely is an artistic statement too.

Greetz
Leendert

--

Leendert A. Hartog AKA Hirazi Blue
Administrator NOT the owner of si-community.com 

Re: realistic hair shading SI-MR

[Leendert A. Hartog]

Any chance of achieving better results with 3delight (as it's so "budget 
friendly"), possibly with custom shaders?


Greetz
Leendert

--

Leendert A. Hartog AKA Hirazi Blue
Administrator NOT the owner of si-community.com

Re: realistic hair shading SI-MR

[Rob Chapman]

yeah sorry Hirazi I clearly saw, its just the latest and greatest theories
of shading hair are including in the redshift hair shader and rendering
tens of millions in 20 - 30 seconds wheras mental ray for softimage...
 when was the last time a decent new technology researched shader come out
for it.. and for SI? and be able to render in any kind of reasonable
timeframe. depending on   which version of mr are you using? the latest?
there may be some new shader tech with the mila shaders am unaware off with
sss but in my humble opinion if it does not do this dual scattering stuff
(which is in RS) it is not realistic enough...

http://www.cemyuksel.com/research/dualscattering/



On 6 December 2014 at 12:16, Leendert A. Hartog  wrote:

> Okay, this was intended as a thread with a serious question about hair
> shading in MR,
> but it's turned into a Redshift infomercial. ;)
> If I had the funds at my disposal, I already would have bought it.
> Ah, well, a bald human head definitely is an artistic statement too.
>
>
> Greetz
> Leendert
>
> --
>
> Leendert A. Hartog AKA Hirazi Blue
> Administrator NOT the owner of si-community.com
>
>

Re: realistic hair shading SI-MR

[Leendert A. Hartog]

Okay, this was intended as a thread with a serious question about hair 
shading in MR,

but it's turned into a Redshift infomercial. ;)
If I had the funds at my disposal, I already would have bought it.
Ah, well, a bald human head definitely is an artistic statement too.

Greetz
Leendert

--

Leendert A. Hartog AKA Hirazi Blue
Administrator NOT the owner of si-community.com

Re: realistic hair shading SI-MR

[Mirko Jankovic]

Just have to add redshift is god send and life saver esspecialy for
freelabce work :)
On Dec 6, 2014 1:09 PM, "Mirko Jankovic"  wrote:

> Some time ago i spent couple months trying to render hair i. Mray. In the
> end all the time wastted and all the issues and speed wise when you count
> it is more expensive to do it with mray then to buy single redshift lic and
> solve or your rendering problems if you have any decend nvidia card
> On Dec 6, 2014 12:15 PM, "Leendert A. Hartog"  wrote:
>
>> Sadly, like I stated, that is not an option, financially (very poor
>> hobbyist).
>> But there must surely have been something people did before the advent of
>> usable renderers?
>>
>> Greetz
>> Leendert
>>
>> --
>>
>> Leendert A. Hartog AKA Hirazi Blue
>> Administrator NOT the owner of si-community.com
>>
>>

Re: realistic hair shading SI-MR

[Mirko Jankovic]

Some time ago i spent couple months trying to render hair i. Mray. In the
end all the time wastted and all the issues and speed wise when you count
it is more expensive to do it with mray then to buy single redshift lic and
solve or your rendering problems if you have any decend nvidia card
On Dec 6, 2014 12:15 PM, "Leendert A. Hartog"  wrote:

> Sadly, like I stated, that is not an option, financially (very poor
> hobbyist).
> But there must surely have been something people did before the advent of
> usable renderers?
>
> Greetz
> Leendert
>
> --
>
> Leendert A. Hartog AKA Hirazi Blue
> Administrator NOT the owner of si-community.com
>
>

Re: realistic hair shading SI-MR

[Leendert A. Hartog]

Sadly, like I stated, that is not an option, financially (very poor 
hobbyist).
But there must surely have been something people did before the advent 
of usable renderers?


Greetz
Leendert

--

Leendert A. Hartog AKA Hirazi Blue
Administrator NOT the owner of si-community.com

Re: realistic hair shading SI-MR

[Rob Chapman]

If you can expand your rendering choices I can highly recommend redshift
for quality of shader & speed
On 6 Dec 2014 10:25, "Leendert A. Hartog"  wrote:

> What would be the "best" shading solution for rendering (more or less)
> realistic hair in Softimage using Mental Ray (sadly: financial
> constraints)? Note: shading/rendering hair, not "creating" it. Are there
> still any custom solutions "floating around", like the ancient muhhair and
> such?
> Any other pointers for getting the best possible result would be more than
> welcome. Thanks in advance.
>
> (Inspired by a question on the German xsiforum.de BTW)
>
> Greetz
> Leendert
>
>
> --
>
> Leendert A. Hartog AKA Hirazi Blue
> Administrator NOT the owner of si-community.com
>
>

realistic hair shading SI-MR

[Leendert A. Hartog]

What would be the "best" shading solution for rendering (more or less) 
realistic hair in Softimage using Mental Ray (sadly: financial 
constraints)? Note: shading/rendering hair, not "creating" it. Are there 
still any custom solutions "floating around", like the ancient muhhair 
and such?
Any other pointers for getting the best possible result would be more 
than welcome. Thanks in advance.


(Inspired by a question on the German xsiforum.de BTW)

Greetz
Leendert


--

Leendert A. Hartog AKA Hirazi Blue
Administrator NOT the owner of si-community.com