Two sided material takes forever

[Skif]

After watching another great tutorial from Fernando with an explanation on how to create a two sided translucent and transparent material I found out that for some reason when I try to do something like that it literally takes forever. I left it on overnight and when I woke up it didn't even finish building a light catch.

The problem seems to be with the transparency of the diffuse layer that I use for a two sided material. Couple of month ago I saw a topic here somewhere in which people were talking about how transparency just doesn't work in the current version of VRay so I was wondering if there was any update on this issue or any workaround? I'm using a previous version, the one with enabled "History" tab, so that maybe a part of the problem?

Please help

[andybot_cg]

Re: Two sided material takes forever

I've been playing with the 2sided material recently, and have some observations. First question - do you want something that is only translucent or do you need to see through the material? If translucent only, you do not need to have the base material transparent at all, and check the force 1 sided box. For a transparent material, it takes much longer to render if you have a refraction layer. Are you able to use the material without refraction? That could speed things up.

[Skif]

Re: Two sided material takes forever

I've been playing with the 2sided material recently, and have some observations. First question - do you want something that is only translucent or do you need to see through the material? If translucent only, you do not need to have the base material transparent at all, and check the force 1 sided box. For a transparent material, it takes much longer to render if you have a refraction layer. Are you able to use the material without refraction? That could speed things up.

Thanks for participating.
I do need a transparency on this material. Basically I'm trying to create something like this :
http://www.interiordesign.net/photo/...t_Athletes.jpg
with some silhouettes being visible through the glass. I didn't use any refraction layers at all. All I have is Material "A" is a two sided material with some translucency (Force one sided and color changed to gray) and material "B" with only diffused layer with some transparency which I use in both paths of material "A". Unfortunately I can't access that scene right now to post it here.

[iamcapitano]

Re: Two sided material takes forever

Last i heard from fernando is that there is a bug with semi-transparency in the current build, i used to have 1 semi-transparent material and used it for a 2 sided material and it worked fine.

Very annoying bug i must say!

Can any admins give an update if this will be fixed soon?

This + copying components with materials from one file to another without losing material properties are terrible bugs that are really causing a lot of problems in workflows, so please give us an update.

[iamcapitano]

Re: Two sided material takes forever

I've been playing with the 2sided material recently, and have some observations. First question - do you want something that is only translucent or do you need to see through the material? If translucent only, you do not need to have the base material transparent at all, and check the force 1 sided box. For a transparent material, it takes much longer to render if you have a refraction layer. Are you able to use the material without refraction? That could speed things up.

Thanks for participating.
I do need a transparency on this material. Basically I'm trying to create something like this :
http://www.interiordesign.net/photo/...t_Athletes.jpg
with some silhouettes being visible through the glass. I didn't use any refraction layers at all. All I have is Material "A" is a two sided material with some translucency (Force one sided and color changed to gray) and material "B" with only diffused layer with some transparency which I use in both paths of material "A". Unfortunately I can't access that scene right now to post it here.

To achieve silhouettes like that you don't need transparency, just give the standard material a refractive layer with glossiness 0.8 in material B then put a sillhoutte figure behind the model. I did a quick test:

[Skif]

Re: Two sided material takes forever

Thanks for you help IAMCAPITANO.
That is exactly what I did at the end, just reduced glossiness of the refraction, here is what I ended Up with -

But even that took 14 hours to cook. of course there is also displacement and DOF but without the glass it takes slightly more that an hour.

[derek_bandit]

Re: Two sided material takes forever

love the opaque glass, need to detail some similar screens with uplighters & downlighters

[fpedrogo]

Re: Two sided material takes forever

The glass material looks awesome.
Best

[andybot_cg]

Re: Two sided material takes forever

But even that took 14 hours to cook. of course there is also displacement and DOF but without the glass it takes slightly more that an hour.

Eh - like I said, frosted glass refraction will take forever.... You can try reducing your subdivs, but it will give you a more grainy appearance.

[Skif]

Re: Two sided material takes forever

I've been playing with the 2sided material recently, and have some observations. First question - do you want something that is only translucent or do you need to see through the material? If translucent only, you do not need to have the base material transparent at all, and check the force 1 sided box. For a transparent material, it takes much longer to render if you have a refraction layer. Are you able to use the material without refraction? That could speed things up.

Thanks for participating.
I do need a transparency on this material. Basically I'm trying to create something like this :
http://www.interiordesign.net/photo/...t_Athletes.jpg
with some silhouettes being visible through the glass. I didn't use any refraction layers at all. All I have is Material "A" is a two sided material with some translucency (Force one sided and color changed to gray) and material "B" with only diffused layer with some transparency which I use in both paths of material "A". Unfortunately I can't access that scene right now to post it here.

To achieve silhouettes like that you don't need transparency, just give the standard material a refractive layer with glossiness 0.8 in material B then put a sillhoutte figure behind the model. I did a quick test:

How many Subdivs are in your refraction?

[iamcapitano]

Re: Two sided material takes forever

That test was done with really low settings everywhere, refraction subdivs was 8 too. I recommend not rendering with dof and learn to use z-depth maps instead, it'll save you HOURS of time literally. I really like your render though, the silhouettes look great!

[Skif]

Re: Two sided material takes forever

Sorry to bother but is there any good tutorials on z-depth subject? Coz I agree, DOF does take forever specially when you have to do 10 test renders to set it right
Lately I use Photoshop for DOF illusion.