Mental Ray SSS Skin Shader Multi/Sub-Object Problem

#1

Hello,

I’m currently starting to texture a character and already did the UVs. I divided the the Editable Poly in 5 Material IDs (head, body, arms…), so i can paint a hi-res texture for for each Material ID.

My Problem here is, that I want to use the Mental Ray SSS Fast Skin Material for every Material ID.
So I made a Multi/Sub-Object Material with 5 SubMaterials and assigned the Mental Ray SSS Skin Material to each SubMaterial (1-5).

I didn’t use any textutes yet and when I rendered the object it seems that the SSS Shader is not working as it should. Because when I assign one SSS Shader to the whole object it works just perfect.

Here is a small test scene I created and the rendered image (ON THE RIGHT THERE IS JUST ONE MATERIAL ASSIGNED AND ON THE LEFT THE OBJECT HAS A MULTI/SUB-OBJECT MATERIAL WITH 2 MATERIAL IDs)

Am I doing something totally wrong or what ?
I hope that someone can help me to get this working as it should.
Thank you very much in advance.

Mental Ray SSS Skin Shader Multi/Sub-Object Material Test File

#2

Can someone please tell me if the test file can be downloaded and opened correctly.

Would also be great if somebody can tell me if the scene renders the same way on his system like in the picture I showed above.

Thanks

#3

mr has a problem with multi-subobject…

a work around is to break the character into the 5 pieces. and map them seperatly. Then put a poly object modifer on top to tie the character back together with attach.

#4

Thank you for your reply.
I detached the parts, put a material onto each of them, then I put a Edit Poly modifier on top of one part. I attached the other parts back to it and rendered, but the SSS Shader doesn’t look the same as if you render the whole object with just one shader assigned to the whole body.

So I guess I have to use just one SSS Material for the whole character with one huge map for the entire character, so that the SSS Shader works how it should.

The SSS material is really great, but how can someone make use of it in creating characters, if it does work with Multi-Subobject.

#5

i agree with you, this is a big problem!!!

i just suggest you try to post this here : http://www.cgtalk.com/showthread.php?p=1916033
Hope to see a good solution too :wink:

#6

Thank you for giving me the link to the thread.
I also posted my problem at the discreet forum but I didn’t get any replies.

I also tried to put a “Material to Shader” Map in to the color channel of one SSS Skin Material and in the “Material to Shader” map I put a Multi/Sub-Object Material with 5 different materials (head, body…), put the results aren’t the same as with just one SSS Shader with one big color map.

So I guess, I have to try same other methods.

#7

here is the solution:
create a SSS Fast Skin Material, then in the “Overall diffuse coloration slot”, choose “Material to shader”, then choose your “Multi/Sub_Object” as last material.
Working for me.
Hope this will help you… Waiting your reply :wink:

#8

Thanks for the help. I tried it and it seems to work, but I recognised that the Shadows where alot darker compared to just one SSS Skin material without any Material to Shader maps. So I think have to make the maps a bit brighter.

Maybe we see a nice working SSS fast skin shader that works also with Muti-Subobject materials in the next version of mental ray…

Again thank you for your help.

#9

hi i just bumpt into this treath, i’m not a max user but i had this problem inn maya.
my soulution was to connect all the light to alle the miss_fast shaders and the lightmap shader.

but than again i don’t know how this works inn max

#10

Osaires,
thank you for sharing your knowledge with me, but unfortunatly i think in max there is no such an option to link or connect light to a shader. But I’m not a pro when it comes to max’s materials.
Normally in max you I just create material from some standart materials in the material editor and then apply them to the model. And there is no need for connecting light source to the materials.

I’m sorry, if I’m totally wrong with what I’m saying, but I sure check the manual or help from max as soon I got time and see what I can find about it.

#11

Minimi13,

EDIT, Misread post.

I made a sphere with 4 mat ids with the fast SSS skin material.

I added a Material to Shader to the bump channel of the fast SSS and chose a multi/sub-object material with 4 mat ids. I added some noise to Mat 4’s bump channel and that worked.

Did you find a good solution for the colour problem (without the dark areas)?

#12

I didn’t get the chance to work on this and other problems regarding the Fast sss skin shader for quite some time, but i now have couple of free days and I’ll see what I can do about the problems I had.

I’ll post some updates as soon as find a good solution.

#13

You could use the lightmap option as described here:
http://www.cgtalk.com/showthread.php?t=209628&highlight=shellac

I posted this info at the Discreet web-board as well. Mitch Gates found a way to combine the info above and make the Multi-subobject material work. Here’s his post:

"Jeff,

I was able to get the trick to work with MutliSub materials by putting the Multisub in the first slot of a Shellac material (Shellac Color Blend set to 0%). Not every elegant but at least it works. Guess the same concept would work with any material with a MentaRay Connection rollout that allows you to put the Multisub one in a slot and use it at 100%

The great thing is that these tricks also seem to network render correctly across multiple machines.

-Mitch"

#14

Jeff Patton

Thank you very much for that info.
I’m going to test it and post the results here as soon as I can.

Thanks again.

#15

So i did some tests and this is how i made it to work without having to change the subsurface.mi files or so.
I hope you understand what I did, to make the SSS fast skin shader work with multiple material IDs in the overall diffuse color slot for example where you can put as many different textures for the different bodyparts of a model.
I just used the same color for every material ID (I’m to lazy to paint some textures now).
Would be nice to get some feedback, if it is useful for you guys.

C&C are welcomed. If you don’t understand the picture above feel free to ask and I’ll explain it better.

#16

I tested out the Ink and Paint multisub and it works great with SSS fast skin!

Does anyone know of a way to assign another material to a character using SSS fast skin? I have a character (mat 1) with jeans and a tee shirt (using mat 2 and 3). If I add another material to mats 2 and 3 the SSS doesent work. The clothes and the body have to be one mesh so I can use the Skin and Skin Morph modifiers.

#17

The fast SSS shaders DO NOT work with standard 3dsmax7. This is because the shader needs a light map to enable fast rendering, and the shader cannot handle creating the multiple light maps for a multi-sub. You can I beleive pre-render the light map for the whole object and then tell the SSS shaders to do it. But I understand you have to hack the shaders and get your hands dirty for this.

Chris Thomas
www.cg-academy.net

#18

post #13 of this thread…

#19

Jeff,

Were you referring to this or the lightmaps?

I haven’t worked it out yet. Could someone tell me what I’m doing wrong here? :blush:

My character is made up of just 3 mat ids. Mat 1 is the skin/body; mat 2 & 3 is for the clothes.

When the body is detached from the clothes the SSS works (as it should). If I attach them together I lose the SSS completely. I used a shellac material and put a Multisub in the base slot. In the multisub I have SSS fast skin in mat 1. That didn’t work.

#20

Both. Mitch’s quote is referring to the lightmap info I posted. So follow the lightmap info first, then follow Mitch’s info.