translucent curtains

[flipside]

Hi,

I'm trying to create curtains that are lit from behind. They are not transparant but light can come through, so I thought this would be a good place to use translucency.

But I'm having lots of troubles. Here are my test images:

Scene setup: a room, a curtain, a vray light, a cylinder to cast shadows on the curtain and a green plane to act as environment (for refraction puproses, see later)



Render1: no GI, no translucency:




Now with translucency, with glossy refraction set to 0.99 (otherwise translucency doesn't work). Note that refraction color is set to black. The image looks like it's working.



Glossy set to 0.9, the lower the glossy, the lighter the curtain gets.



Here with a lower IOR, nothing happens. I also tried various settings for the translucency but none of them have any effect on the rendering. This is probabely due to the curtain that has no thickness, it's just an extruded line.



Here with GI turned on! Suddenly we can see through the curtain! Refraction color is still pure black!



Skylight turned on:



Vray light turned off:



From the moment GI is on, the curtain suddenly acts as a transparant surface, if I change IOR now, the effect is clearly visible.

I really want to create a non transparant curtain. The material is white (or something else) and the cloth is pretty thick. So it's not one of these curtains where you can look through very good. But light should come through and illuminate the room. I can't show you the pick I'm trying to recreate because it's in a magazine and my scanner is not working.

Any ideas on getting this right? How do you guys create and render curtains?

Thanks for any tips,

flipside

[Invoid]

RE

its russian,but i hope you understand it
http://www.darc.ru/Lib/Lessons/lesson49.php

[restoeboemi]

http://www.chaoticdimension.com/foru...pic.php?t=3045

im using map in refraction slot, with cast shadow on, no translucent

[flipside]

Invoid, thanks for the link, I'll try to figure it out

Restoeboemi, I found that post already , thanks anyway! These curtains are too transparant compared to what I want. I thought I could do it without refraction, as it gives weird results. What ior did you use?

[restoeboemi]

i use IOR 1.0, if the result too transparent maybe u could play with ur map, try to blur, or change the UV size/tiling.

[Psy]

i have an idea on how to do it, gimme a lil bit and I'll see what my results are.

Mind you, I'm not gonna use translucency.

[PATER]

oh, pretty good topic...

i had problems with soft curtains as well.
I used a big VrayLight as simple white Skylight-Replacement as a side of the Room, cranked up to 5...

The Value made a good light in the room but it was to bright for the curtains. I had simple 50% transparent (1.0 IOR) White Material like some people did in thier pictures. They became totally white. With a little glossiness blur and transclucency they became more natural, but i didnt managed it to get them like real curtain...

So i became a little curious about your link Tutorial... Whats the Trick there...? no Scene to download and russian by the way... thats sad...

It seems they use 2 Curtain Surfacesm one simple white and one Orange... and their settings... glossyness 1.0 + translucency with Thickness 1.0... how does this work??? also, whats the deal with the scatter and Fwd/Bwd coeff. ? 0,999999 ? And is it usefull to tweak the color mapping for transparent sss-Curtains?
Damn, i wanna know how it works!

Hopefully someone or something (a scene) can clear this up!



much appreciated, these curtains look fantastic!

[lukx]

I did everything like is http://www.darc.ru/Lib/Lessons/lesson49.php and but there's no translucensy!!! What's wrong with Vray?!

[flipside]

Didn't test it yet, but don't blame vray! Double check everything. At first sight the tutorial makes sense and should work imo.

[minimum]

interesting challenge we got here...

I visited that tutorial page and took some time to translated trough the altavista translation service...


http://babelfish.altavista.com/babel...p=ru_en&tt=url

perhaps it's not ideal but at least it's more accesible.

cheers

[lukx]

here you go boys...I've created this scene...now tell me where's my mistake (it's max 5.1 file)... http://lukx.hellnet.gliwice.pl/curtainsvray.max

[egz]

I did everything like is http://www.darc.ru/Lib/Lessons/lesson49.php and but there's no translucensy!!! What's wrong with Vray?!

If you look at the screenshots in the tutorial, you will see that it is using an old version of the VRay material. Some time ago the translucency algorithm changed, so you will probably have to use other material settings now.

I would take a shot at it if I had time, but I have to get back to what I'm supposed to be doing. I might get a chance to do it tomorrow unless someone else beats me to it

[lukx]

I did small scene update so now all settings of vray are the same as in tutorial. But still it just dark scene =( If in older versions of vray translucency algorithm worked fine why it was changed?

[marina]

In your scene, i hide white courtain to make some tests with the orange courtain. I realized that if you colapse to mesh and invert normals, translucency begins to work. Hope this helps

[marina]

But i have problems adjusting IOR. I put refract to 0, but IOR afects a lot final result of translucency, so what IOR must be used for the courtain. An IOR of 1 doesn't work, because "flatten" (courtain appears like a plane)the result