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I spotted various threads claiming that IBL would greatly enhance speed of scenes involving SSS materials.
First, I'd like to know the reasons for that, and I would like to know whether this is also true for Single Sided SSS...
I use this material a lot : http://www.box.net/shared/static/mcd4c8glup.mxm , but it is generally too noisy for interior views where the only light comes from outside (sun).

Also : would Sky dome help over Physical sky ?

Just thought I'd ask before hunting for HDR images, finding the right offsets to get the sun in the right location, fiddling with the intensity coefficient, etc...

Thanks

*Blizzard sound*

Yes, but not all IBL is created equal -- so how much and what quality depend largely on the images you choose.

Also worth noting is you can render a HDRI of the physical sky and use it as IBL for quick experiment to see if you get better results from IBL... a free and efficient solution that requires very little adjustment on your part.

Single sided should not have strong noise problem -- it may be a problem with unrealistic material parameters and not with lighting solution.

Sky dome is better as it is homogeneous lighting -- and it is what is used in the SSS preview scene for this reason. However it is very boring/flat looking and IMO should only be used in situations where you cannot directly see outside lighting and simply need ambient glow.


Best,
Jason.

Hi Jason,

Thanks for the interesting ideas.
I'll try the render of a physical sky as HDRI, but could you point me to a specific HDRI that generally produces good results ?

I'll also try to tweak the material, but frankly, I find it tough to fiddle with those SSS parameters.

There is also currently a nasty bug with SSSSS : https://smc2.box.net/shared/static/eyeevc6evs.png
NL : Any idea when this will be ironed out ?

Cheers,

--
Olivier

osuire wrote:There is also currently a nasty bug with SSSSS : https://smc2.box.net/shared/static/eyeevc6evs.png
NL : Any idea when this will be ironed out ?

You should post this one in bugs section, too.
Did this appear with the last update?

This is an older thread -- I did some tests as soon as 2.5 was released and showed true SSS is currently far superior to thin SSS here:

http://www.maxwellrender.com/forum/view ... 97&t=35734

Best,
Jason.

I think Oliver is trying to point out the fact that Single Sided SSS is seen through all the materials/geometry - in this case wooden construction etc..
Or am I missing something

Yeah, I was referring to his questions at the beginning of the thread and about IBL -- IBL is not needed or even preferred for current SSS which is much improved in 2.5 over what it was when he originally asked the questions.

For that matter IBL has an issue with reflective caustics as you can see here:

http://www.maxwellrender.com/forum/view ... 97&t=36001

So under the current situation my recommendation would be to use real SSS and the Physical Sky as opposed to thin SSS and IBL -- six months ago I would have said the opposite(and did).

Best,
Jason.

Hi guys,

Sorry I kind of made a digression with the "See through" bug.
I have sent a file where this is reproductible, and NL has acknowleged it, but it's been some time now, and this is quite embarassing for me since I am not able to produce proper renderings for my work.

Regarding using SSS over thin SSS, well... it seems to me I would have to make a solid out of the membranes with something like 2 mm thickness for this to work.
That would be really challenging, plus it would be very tough to avoid the SSS "thin solid" from crossing other geometries thus provoking funky artefacts...

Thin SSS is a good concept for membranes, curtains, leafs, but I just can't seem to find parameters which will not creat huge amounts of noise (not to speak about the nasty bug).

Cheers,

--
Olivier

Illustration of my previous message here :


The material becomes indeed less noisy, but does not behave as required at all : it becomes translucent and does not show the shadows through.
This is because SSS materials need some kind of thickness.

If anyone had an idea how to tweak my thin SSS material to make it less noisy, it would certainly help me A LOT !
I render these types of views all the time...
Here's the material : https://smc2.box.net/shared/static/lfppudco8x.mxm

Cheers,

--
Olivier

i don't get why the leaf plane shadows come across as square outlines planes and not the outline of the transparent leaf image

This will reduce the noise -- although not being able to test it in you scene makes it hard to judge.
http://www.spotoarts.com/jason/polyester_pvc_jason.mxm

Best,
Jason.

Arrrrglll !
Link no longer working !
This was too good to be true

Could you point out what change you made is likely to improve the speed ?

Cheers,

--
Olivier

I fixed the link -- but I should warn you again thinSSS is functioning very much subpar at this point and it won't be ideal.

Best,
Jason.

Thanks Jason,

I'll check it out on Monday !

Cheers,