Author Topic: SSS Pancake  (Read 15013 times)

2015-12-01, 23:56:38

marioteodoru

  • Active Users
  • **
  • Posts: 96
    • View Profile
Hello,

I am trying to achive a puffy pancake look, but all i get is a stone pancake. I don't seem to be able to control SSS. A value of 1 cm looks the same as a value of 1000 cm.
The  object is at scale. But the geometry intersects inside. Maybe this is the issue? I made a mask to define the area i want to have sss. It seems to work with translucency but the effect is not usable. Does anybody can offer me an ideea? How can i make sss fuzzy  ? control the density? anything? I found a material in vray that has 3 sss layers. Does this works with corona layers?

2015-12-02, 10:27:29
Reply #1

DarcTheo

  • Active Users
  • **
  • Posts: 175
    • View Profile
Hello,

I am trying to achive a puffy pancake look, but all i get is a stone pancake. I don't seem to be able to control SSS. A value of 1 cm looks the same as a value of 1000 cm.
The  object is at scale. But the geometry intersects inside. Maybe this is the issue? I made a mask to define the area i want to have sss. It seems to work with translucency but the effect is not usable. Does anybody can offer me an ideea? How can i make sss fuzzy  ? control the density? anything? I found a material in vray that has 3 sss layers. Does this works with corona layers?

Not really had success with Corona SSS either but have you read through this for SSS control? - https://coronarenderer.freshdesk.com/support/solutions/articles/5000534910-how-to-use-subsurface-scattering-volumetric-absorption-and-scattering-

2015-12-02, 13:51:11
Reply #2

maru

  • Corona Team
  • Active Users
  • ****
  • Posts: 12718
  • Marcin
    • View Profile
I think that the kind of lighting you showed in the image prevents the SSS effects from being observable. You should use strong, directional light, or if you do not wish to use it in the final render, you could use it just for testing purposes to see how the material behaves in different lighting conditions. A strong light will exaggerate the SSS effect, which can be useful to make it more subtle afterwards.

I also think that it is more important to find correct SCATTERING color than ABSORPTION color. In the picture you posted I can see that you have absorption set to some values, but scattering color seems to be pure white. Maybe changing it could bring some improvement here.
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2015-12-17, 12:04:06
Reply #3

marioteodoru

  • Active Users
  • **
  • Posts: 96
    • View Profile
Hello,

i'm back with some updates. I am trying the following process. Split my mesh in 3 parts. The outer shell, the inner core, and the chocolate filling.

I have to say, am very confused. I CAN NOT UNDERSTAND THE RELATION BETWEEN Translucency, Absorption, Scattering and Opacity. And, again, please excuse my caps, but
I SHOULD'N HAVE TO SPENT 2 WEEKS TRYING TO GET THE RIGHT SSS IN THE MIDDLLE OF A DEADLINE.

The help section is quit general. Like use any other color than white. Really ?!?!  I did some tests and the relation between  Absorption colors and scattering colors is totally random for me. I have no special knowledge in sss, but from my research you need to make special measurements to determine sss colors.
Anyway, let me get back, sorry for the rant.

I am trying to get that fuzziness specific to this kind of objects. I tried endless combinations.  The only factor that seems to bring me closer to what i want is OPACITY. But i don't understand. For me opacity is ... .... actually what is opacity? I consider it is transparency. But do pancakes have transparency? I tried adding different noise to the surface, but i don't get there yet.
What is most confusing to me, is that it seems that increment values like 0,001 have a big influence, but big values like 500 for absorption does nothing. Is absorption sensing the real with of the object and stops when it reaches the limit?

I acquired this render engine hoping i will get out of the maxwell infinite rendering times, but it seems i got nowhere. Actually a 1 million poly object with sss and opacity puts corona down in a never ending initial pass. How do i get fuzzy SSS?!?! Do you guys have something like a customer care service or something? Can i pay to have my problem solve or do i have to get back to maxwell?

Thank you.



2015-12-17, 15:18:34
Reply #4

maru

  • Corona Team
  • Active Users
  • ****
  • Posts: 12718
  • Marcin
    • View Profile
Hi,

i'm back with some updates. I am trying the following process. Split my mesh in 3 parts. The outer shell, the inner core, and the chocolate filling.
That will probably require some different workflow than what you showed before.

Quote
I have to say, am very confused. I CAN NOT UNDERSTAND THE RELATION BETWEEN Translucency, Absorption, Scattering and Opacity. And, again, please excuse my caps, but
I SHOULD'N HAVE TO SPENT 2 WEEKS TRYING TO GET THE RIGHT SSS IN THE MIDDLLE OF A DEADLINE.
I can understand your frustration.  Honestly the SSS controls are confusing for me too. I requires a lot of trial and error before you understand more or less what happens when.

Quote
The help section is quit general. Like use any other color than white. Really ?!?!  I did some tests and the relation between  Absorption colors and scattering colors is totally random for me. I have no special knowledge in sss, but from my research you need to make special measurements to determine sss colors.
Anyway, let me get back, sorry for the rant.
I think that setting absorption to pure black and changing only its distance value only + setting scattering color to some custom one makes SSS easier. But that is just one possibility.

Quote
I am trying to get that fuzziness specific to this kind of objects. I tried endless combinations.  The only factor that seems to bring me closer to what i want is OPACITY. But i don't understand. For me opacity is ... .... actually what is opacity? I consider it is transparency. But do pancakes have transparency? I tried adding different noise to the surface, but i don't get there yet.
What is most confusing to me, is that it seems that increment values like 0,001 have a big influence, but big values like 500 for absorption does nothing. Is absorption sensing the real with of the object and stops when it reaches the limit?
My personal explanation would be pretty much like at helpdesk:

Imagine the 3ds max mesh as a "shell" - something that does not have wall thickness, or has close to 0 wall thickness. Like a sculpture made of thin layer of paper, which is empty inside. Then:

Let's forget about absorption and scattering. Let's focus on the material from which the shell of the object is made and let's imagine that it's diffuse level i 0 (it is pure black).

Opacity - reducing it will make more light pass through the shell material. 50% opacity will mean that 50% of light will get through into the inside. The light which gets through continues with the same direction as it entered.
example: stocking - a material with tiny holes in it. The holes are so tiny that they are never visible, but decreasing opacity makes the holes bigger up to the point where there are only holes.

Translucency - increasing the fraction value will "transfer" X amount of light to the other side, where it will be scattered. The light which gets inside is scattered.
example: paper - imagine what happens when you illuminate a sheet of paper with flashlight - observe the sheet from both sides.

Refraction - basically the same thing happens as with opacity, only the light which gets inside is bent by the IOR. And we are not thinking with holes here as you can, for example, enable reflections here.
example: glass. If refraction is not 100% then you can imagine glass with a tiny layer of transparent paint on top.


Absorption:
Now, remembering all of this, imagine you are changing the color of the inside of the object. If it's glass (refraction) you can imagine that you are adding some kind of dye to the glass in the process of making it. If it's paper (translucency) or fabric (opacity) you can imagine pumping some gas inside, which has different color than light.

color: red
distance: 5cm
This means that if white light enters, after 5 cm it will become red, and after that it will start getting darker and darker* until it completely extinguishes.
0cm-white-------------2,5cm-pink-------5cm-RED----------------darker--------darker--------------no light

*actually it is not becoming darker but it gets divided further and further, so you get something like linear light (?) operation in photoshop.


Scattering:
Now, still remembering all of the above, imagine you are pumping some kind of gas inside of the object, or putting lots of microscopic objects inside, that pass some light through them, and bounce it around.
Color - it is the color of the tiny particles. The brighter the color - the more light the particles will let through and scatter around.

If it's not very close to physical-correctness, or what really happens in Corona, I think it still helps to imagine what is going on with SSS on.

Quote
Do you guys have something like a customer care service or something? Can i pay to have my problem solve or do i have to get back to maxwell?
Sure, go ahead and submit a support ticket:
https://coronarenderer.freshdesk.com/support/tickets/new
We will be happy to take a look at the scene. Too bad you didn't do this earlier. It's partially my fault, I could have suggested it. The problem here was that you did not write how important this is for you. We did not know if it's some commercial project, or if you are just making the doughnut for yourself/test. That's why it's best to contact support. Your message will never be ignored there.

It would be great if someone with higher level than me could check what I wrote and possibly correct some mistakes. ;)
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2015-12-17, 20:44:51
Reply #5

marioteodoru

  • Active Users
  • **
  • Posts: 96
    • View Profile
Thank you so much maru. your explanations are great and thank you for taking your time to wrote this to me. I do have some basic knowledge of shading and i know what most of the attributes mean.

i will try to approach the shader again, and if i don't succeed, can i ask help? I mean, this is not basically a bug or something. I don't even know what kind of problem this is. So i can get assistance in getting the shader i need? Some one can look at my file and help me solve this? Is it for free? 

Am i to understand that if i construct the shader correct, i will get the effect i want ? I don't even know now, if i think about it, if i should have sss. maybe i should just put a little opacity. but how do i get the fuzzyness ? Is is possible that the only way to do it is to model the macro geometry of the crust? Man, i did a lot of research on pancakes and bread, and porous structures. I even build the inner core with a voxel and voronoi. But i get very dense geometry, and it still doesn't look right. O the other hand, the only "pretty good" bread i've seen it the pixar one in ratatouille. And they build a special shader for it.

So, has anyone any idea, if what i'm looking for is determine by sss, or can be simulated with sss, or do i have to build the actual geometry?

I hope i didn't bother anyone with my tone. I'm just really frustrated. I should've finish this project weeks ago, and i got stuck in this point.

Thank you for your time maru.

2015-12-18, 12:27:25
Reply #6

tomislavn

  • Active Users
  • **
  • Posts: 706
  • Lightbringer
    • View Profile
    • My 3docean Portolio
Heh, really interesting topic to be honest!

A few weeks ago I did some pancakes scene in 15-20min since I had that idea of some food render - but I quickly gave up. Not really sure the effect is there though, I was playing with SSS but gave up since I couldn't get it right also. It wasn't American pancakes though :P

Here's the 25 passes render in few minutes. Material is quite simple - pancakes texture, slight translucency and shallow SSS with bump noise and vector displacement.

Anyway, I am also interested in how could I make them look more "fluffy and soft" without actually modeling it. If needed I can send you the test scene - it's quite simple.

EDIT: Added a new render from today :p little bit of tweaking
« Last Edit: 2015-12-18, 15:32:58 by tomislavn »
My 3d stock portfolio - http://3docean.net/user/tomislavn

2015-12-18, 18:31:27
Reply #7

marioteodoru

  • Active Users
  • **
  • Posts: 96
    • View Profile
Hi,

i got a little progress today. I've added displacement over the bump. This bring a little more fuzziness from the geometry perspective, but the texture feeling is still not there.
I think i'm missing a refl. color map but i'm not sure what to derive it from  because i have a bump map and a different displacement map. 

The main issue now is that by adding displacement map and reducing opacity plus sss, increases the render time a lot! Corona interactive is very slow for this scenario on my system.
It does'n even update, or it does but in like 5 minutes. So what i'm left with is changing by  .1 for a parameter, rendering for 50 passes which means 1 hour in this scenario.

Maru, your explanations did help me, but i still have some clarifications i need.

Do i need a difuse map? If yes, what value? smaller than 0.5 or bigger? I have to say that this 0.5 default value make no sens to me. I just don't get it. Why not 1?  why not 100 ???! Isn't the Color correction map used for increasing brighness? Why all that values sistem that i don't get. I mean i get it. 0.5 it's like 100% over 0.5 is multipling, under is reducing. BUT IS SO CONFUSING! At least to me.

Do i need to use Translucency or Opacity or both ? What color should translucency be? How is the 0.5 paradigm working for translucency? Because to me from  0.5 to 0.6 there's a big jump in intensity, stronger than between 04. to 0.5 .

It's ok if i use the diffuse map, brighten for the Absorbtion and Scatter colour?

using a map for the opacity value  renders the numerical vale mute? Or it still affects?

Thank  you for your advice and i hope you can help me with more answers. I did apply for a ticket.. didn't get an answer yet.

« Last Edit: 2015-12-18, 23:51:19 by marioteodoru »

2015-12-19, 12:11:05
Reply #8

marioteodoru

  • Active Users
  • **
  • Posts: 96
    • View Profile
Well,  i think i found the solution.
First i need to apologize for bashing sss. It seems to work once you start to understand the basics :D . Thanks again maru. Also it seems the fuziness i was looking for comes from displacement rather than sss.

 Render selected feature is a  life saver!

I'm still not sure if my particular object need Translucency or Opacity. I still don't get the relation between this two or if they are supposed to be used together or not.

All is left to do for me is fine tune this and i think i'll get what i want in the end.

2015-12-19, 12:53:17
Reply #9

romullus

  • Global Moderator
  • Active Users
  • ****
  • Posts: 8781
  • Let's move this topic, shall we?
    • View Profile
    • My Models
As for whether to use translucency, opacity or refraction, this post by Ondra helped me a lot. You may want to look at it: https://forum.corona-renderer.com/index.php/topic,8715.msg57294.html#msg57294
I'm not Corona Team member. Everything i say, is my personal opinion only.
My Models | My Videos | My Pictures

2015-12-19, 15:23:09
Reply #10

Jahman

  • Active Users
  • **
  • Posts: 45
  • Panteleev Sergey
    • View Profile
    • some of my scripts for 3ds max
true, that's clarified a lot for me

in your case you surely should be using translucency or refraction with low glossiness which could be a bit faster to render

2015-12-20, 06:03:47
Reply #11

marioteodoru

  • Active Users
  • **
  • Posts: 96
    • View Profile
As for whether to use translucency, opacity or refraction, this post by Ondra helped me a lot. You may want to look at it: https://forum.corona-renderer.com/index.php/topic,8715.msg57294.html#msg57294

Thank you.very  interesting thread. I don't know why but for me Ref 1 with glossines looks nothing like translucency. I don't know why... i'll make some comparative test.

true, that's clarified a lot for me

in your case you surely should be using translucency or refraction with low glossiness which could be a bit faster to render


I am using translucency. It seems no matter what i do, even if now it looks much better. I don't seem to get nowhere near a reallistic appetising feeling. I'm starting to beleive that a better solutions would be to build a more accurate geometric model.

I don't mean to be rude, but your example doesn't reflect the quality i'm looking for. It becomes more clear to me, that, considering corona light goes as real light so, the geometry should do the same.

Thank you guys for you're input

2015-12-20, 07:22:08
Reply #12

Ludvik Koutny

  • VIP
  • Active Users
  • ***
  • Posts: 2557
  • Just another user
    • View Profile
    • My Portfolio
I can make a nice pancake material if someone provides me with a pancake model :)

2015-12-20, 12:39:36
Reply #13

maru

  • Corona Team
  • Active Users
  • ****
  • Posts: 12718
  • Marcin
    • View Profile
I can make a nice pancake material if someone provides me with a pancake model :)
I can make a nice pancake model if someone provides me with a 3d scanner. :)
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2015-12-21, 10:00:14
Reply #14

marioteodoru

  • Active Users
  • **
  • Posts: 96
    • View Profile
I can make a nice pancake material if someone provides me with a pancake model :)
I can make a nice pancake model if someone provides me with a 3d scanner. :)

Hello,

I can provide my model, just tell me where i can upload the file