Curtain and noisy renders

General questions about Indigo, the scene format, rendering etc...
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SreckoM
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Curtain and noisy renders

Post by SreckoM » Tue Jan 12, 2016 8:56 am

Not sure if I did this correctly, but for curtain material, I made Blend and blended one diffuse material and Null. If I add that to curtain it is almost impossible to remove noise in renders. There a a lot fireflies. Compared to render without curtains render times is several times longer. Is there any way I can use different material that will now affect render times so drastic? Using PT Bdir, found it fastest in this case. What should be workaround to have that curtain look something like this http://screencast.com/t/tiaGaWCYDWi and keep render times acceptable, possible?

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Zom-B
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Re: Curtain and noisy renders

Post by Zom-B » Tue Jan 12, 2016 10:22 am

SreckoM wrote:Not sure if I did this correctly, but for curtain material, I made Blend and blended one diffuse material and Null.
Nope, note a good idea :)

Do a blend between a diffuse + diffuse Transmitter Material (D: 80% and DT: 20%)
If your curtain mesh has some depth, the use a gamma of 1 for the DT color, if its single sided, then a gamma of 2.2.

Tweak that 80/20 ratio as you wish, its just a starting point :)
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SreckoM
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Re: Curtain and noisy renders

Post by SreckoM » Tue Jan 12, 2016 10:59 am

Thanks!
When you say 80/20 you mean 20% of blend?

[EDIT] How can I make it more transparent?

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Oscar J
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Re: Curtain and noisy renders

Post by Oscar J » Tue Jan 12, 2016 12:09 pm

You will probably have to blend your blend with a null, to make it more transparent. So you make a blend tree:

Blend1 = 20 % DT, 80 % Diffuse

Blend2 = 20 % Null, 80 % Blend1

Or something like that. :)

An alternative is to use a PNG texture for your fabric with an alpha (transparency) channel for the materials in the blend.

It sounds strange that your render times would increase that much from using a null blend, care to attach some screen shots or test renders?

SreckoM
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Re: Curtain and noisy renders

Post by SreckoM » Tue Jan 12, 2016 12:15 pm

Can not share scene unfortunately. Maybe worth to mention is that I have Exit portals. Also might be a problem that curtain goes over all windows.

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Oscar J
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Re: Curtain and noisy renders

Post by Oscar J » Tue Jan 12, 2016 12:21 pm

Try without exit portals, unless your windows are very small. You could also try EPs + BiDir MLT, since MLT is much less firefly prone.

SreckoM
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Re: Curtain and noisy renders

Post by SreckoM » Tue Jan 12, 2016 12:34 pm

Thanks!

This is comparison between with curtains and without. Same time, around 2min. Mlt Bdir. Much nosier.
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Zom-B
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Re: Curtain and noisy renders

Post by Zom-B » Tue Jan 12, 2016 7:46 pm

SreckoM wrote:This is comparison between with curtains and without. Same time, around 2min. Mlt Bdir. Much nosier.
Since all the light needs to pass your curtains, its quite some extra calculations Indigo needs to do, that snot for free!

for more transparency don't blend with a null, that should slow everything down a lot. Instead use a black + white checkerboard texture set it to step blend and scale the tiling on the curtain down a lot! By that light rays will either hit a full block or full pass in the curtain. this should result in better rendertimes (less fireflies).
For this approach you can reduce DT or even leave it fully away.
The hard part here is to fine-tune transparency further, here for you need to alter the chekerboard mask with bigger black areas, or white for more transparency...

Better use BiDirPT for interiors, and if you really need to use MLT, then raise the "Larg mutation Prob." to 0.85 for more PT like noise behaviour...

For your sunless setup it could be also interesting to set the EPs in your windows to emitters, that emit uniform light, this should speed up calculations too :)
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SreckoM
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Re: Curtain and noisy renders

Post by SreckoM » Thu Jan 14, 2016 5:15 am

Thanks. So Blend material, first slot Diffuse, second slot can be empty? or DT and blend with checker texture. Is that correct?

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Zom-B
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Re: Curtain and noisy renders

Post by Zom-B » Thu Jan 14, 2016 5:26 am

SreckoM wrote:Thanks. So Blend material, first slot Diffuse, second slot can be empty? or DT and blend with checker texture. Is that correct?
Try what gives ya the best results, there are many blending approaches :)
Most important is to us chekertexture with step blend to prevent the whole material to be semitransparent, but instead having tiny holes for the light to pass through!
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SreckoM
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Re: Curtain and noisy renders

Post by SreckoM » Thu Jan 14, 2016 8:58 am

Thank you for your help! I also added few more area lights in room so render is faster now, acceptable :D

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tarikb
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Re: Curtain and noisy renders

Post by tarikb » Wed Oct 04, 2017 8:22 pm

ZOOM-B can you make that curtain material and upload it plz?
I tried but i think i don't do it properly.

Tnx
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Zom-B
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Re: Curtain and noisy renders

Post by Zom-B » Thu Oct 05, 2017 3:18 am

Hey tarikb,

its simply blending DT into a Diffuse with 30%.
I Attached this simple material that I used for the Bedroom Benchmark scene just like that...
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Curtains.pigm
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fourzeronine
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Re: Curtain and noisy renders

Post by fourzeronine » Thu Oct 05, 2017 7:16 am

try a thin double sided material

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