Noise in the reflection table: bug?

[cecofuli]

Hi,

as you can see, in the ceiling and windows I don't have noise.
but look at on the glass table (glass wit absorption).
You can see clear a lot of noise. Why?
DOF with Corona. Corona settings are default.

[Polymax]

You can try render this view in the alpha 4 version?

[cecofuli]

I use alpha4 =) Cause the good old "blur bug" in the daily version. And I don't know if it is fixed.

[Polymax]

I talked about the noise in reflection still in alpha version 3, keymaster said that fixed, it seems that is not fixed (
http://forum.corona-renderer.com/index.php/topic,377.0.html

[cecofuli]

I think the same.

[Polymax]

You publish this work as done? Beautifully turns out!

[cecofuli]

Yes, why not =) This is a WIP

[Polymax]

Great! I Like it!

[cecofuli]

Thanks :)

[Chakib]

what a fantastic render, cheers !

[cecofuli]

Chakib, it's just a simple coffee, but thanks. The shaders are in WIP, as many other stuff.
Another view.
Again, look the noise on the table, after 3 hours... :(

[Ondra]

This is not a bug, just fewer samples are taken when the rays bounce from the table. Corona currently uses NO adaptivity. Just imagine the speed after I add it :D

[cecofuli]

This is not a bug, just fewer samples are taken when the rays bounce from the table. Corona currently uses NO adaptivity. Just imagine the speed after I add it :D

So, do I just need time to remove the noise? When you'll add the adaptivity ^____^' , like in VRay?
and, what about the shadows through the solid glass?
As you can see in my floor, now I use a solid glass with "cast shadows" option disable in the shader.

[racoonart]

This is not a bug, just fewer samples are taken when the rays bounce from the table. Corona currently uses NO adaptivity. Just imagine the speed after I add it :D

May the force be with you! (and with us afterwards!) If you'll make something as powerful as vrays dmc... man, i don't even find something i can say after that :) DMC + Corona fancyness ... wonderful

[Ondra]

This is not a bug, just fewer samples are taken when the rays bounce from the table. Corona currently uses NO adaptivity. Just imagine the speed after I add it :D

So, do I just need time to remove the noise? When you'll add the adaptivity ^____^' , like in VRay?
and, what about the shadows through the solid glass?
As you can see in my floor, now I use a solid glass with "cast shadows" option disable in the shader.

yes, I'll get to it, it's just that I'll need to again dig deep into the core to make that happen. So give me a week or two

[Ludvik Koutny]

If your light sources are large (like windows) then caustics will not converge that slow. Try to set Max sample intensity to about 20, enable shadows in your glass material, and render close up of the chair shadow. I think the shadow will not be opaque, but will converge fast ;) The extreme clamping scenario usually happens only in cases with very small and bright light sources in a very dark environments ;)

Max. sample intensity (MSI from now on) does not make shadows opaque, or disable caustics. It just throws away samples that are significantly different than the average of samples taken from the given point. So if you have very large light, like window, where it will be very easy to calculate caustics even using regular path tracing, then not many samples will have significantly different value than the rest, so not much data will by thrown away and you should get transparent shadows with soft caustics. ;)

[cecofuli]

Again, noise in DOF, like in my old child bedroom. Also, fireflies on transparent chairs.
About DOF, I think I cannot do nothing. 8 hours and 450 passes are too much. I think Keymaster must to do something =(
For fireflies, if I disable the light, everything is ok. But, in the light option, I don't have "disable in reflection/refraction"
Corona parameters as default ( PTS= 32 , MSI 20 )
Some suggestion?  I cannot send to my client rendering with this noise...

[Ondra]

PT samples are 16 by default, right? And you should lower it if you are using DOF, to about 4

[cecofuli]

No, 32, as in the interactive Guide. But I try with 4 in a crop. What about the white fireflies?

[Ondra]

you can try for example disabling the visibility of the light, or lowering max depth

[cecofuli]

Better with PT= 4. Max depth = Ray Depth? Now is 25, by default. Usually in VRay is 5. Or am I wrong?

[cecofuli]

The only way to "solve" (It's better say reduce)  the fireflies is changing "Internal res" from 2 to 4.

[cecofuli]

Or use this free tools. But, obviously, it adds "blur" to the  rendering.

Defly - firefly and hot pixel noise removal tool

[maru]

Or render in huge resolution with "do antialiasing" disabled and then downsample in photoshop.

[Polymax]

Also, fireflies on transparent chairs.

This is Alpha-4 bug! In the last builds is fixed!

[Ondra]

It does not necessarily needs to be. If there is a complicated glass structure, then since on every surface you have both reflection and refraction, the number of possible paths grows exponentially with ray depth, and you get something with fractal behaviour. If you the have thousands of possible ray directions for single pixel, the probability that some of them hit the sun randomly grows, and so you get frequent bright spots. This is physically correct behaviour, and Corona should converge to the physically correct result in the long run, although it is certainly undesirable for this kind of renders.

[Polymax]

Here are the fireflies on transparent objects (post from mantis).
Or is it not?

[Ondra]

which ID is this, this looks like good old NaNs

[Polymax]

0000231

[cecofuli]

With the new version, noise and fireflies. But after 9 hours, the noise is too much.
Any suggestion?

[maru]

More PTS, less MSI.

You can try selecting a small square on the noisy area and letting it render for the same amount of passes that you got after 9 hours. Try changing lights samples multiplier.

You could also show HD cache settings.

[Polymax]

You can post part of scene (with noise and fireflies)? I would tried to help.

[cecofuli]

PTS = 4 for DOF, as Ondra suggested me.  MSI = 50 for better highlight.
HD as default. Never change.  I'll rty with crop and see what happen.

Yes, I have the scene both in VRay and Corona.
I want to clean-up and post here both files.
With VRay and sub-pixel mapping OFF was impossible to render in decent time.
When buckets are  over transparent chairs, DMC sampler becomes CRAZY!!!
This is a "big problem" in VRay, as Vlado wrote me. 
Look my old VRay thread  LINK

If you want to compare VRay and Corona (or MW, Arion, Octane) sub-pixel mapping must be OFF.

IOR for chairs is wrong. And I don't like the shader/color. But this idea is from my architect :(
S curve, CC , Sharp and denoise in PS

[maru]

HD as default. Never change.

Maybe you should try with different settings. You can always revert to original values with right click.

[cecofuli]

good, but I don't know how HD parameters influence the noise XD

[cecofuli]

With the  new daily build, something different in the chairs reflection.
I change a little bit the power of lights, but not the IOR...
I don't like the "back table reflections" inside  the chairs... =(
 
PS: no fireflies ;-)

[Ondra]

yes, it behaves differently, I'll look into it today or tomorrow

[cecofuli]

Ok. Thanks! And... do you have some suggestion for the noise in the black area?

[Ondra]

no... either give it more time or wait for the adaptivity ;)

[cecofuli]

Here the scene just for testing purpose.

As you can see, after one hour, for this resolution, is enough and with double time we don't have significant improvement in the noise quality. (PT+HD)

[cecofuli]

But I don't understand the differences between PT-HD (lighter) and PT+PT (darker)

[cecofuli]

Here a render at 3000px after 9 hours!!!
Good quality after 3 hours, but the noise, created by lights on the reflective surface, is still here =(
Ondra needs to works on this "bug-problem".
 
PTS = 6
MSI =  20
Lights samples = 4

[Polymax]

try set refl.gloss to 0.99 or (0.999) for clear refl, in the alpha 3 it's help me.

[cecofuli]

thanks for the suggestion. I'll try ;-)

[cecofuli]

Polymax, I didn't solved the problem with glossy at 0.99.

sole sligtlhi better result with Lights subdivs, but... I thing we have to wait Ondra and new Corona render.
Too much noise in the reflection lights, after... 18 hours!!!  (Final output 3K)

[Polymax]

In light sources (hidden illumination) visibility is on?

[cecofuli]

As default. I didn't touch nothing.  )

[Polymax]

I tried to repeat, well, maybe other conditions ...

[cecofuli]

Soon I'll send you the full Corona scene =)

[Polymax]

I did a quick test.
Slightly changed the render settings.
Crop mode rendering (therefore, the noise is more than a "view" mode), 250 pass

[cecofuli]

Interesting. What's about the noise on the chrome spotlight, on the top-right side of the brown ceiling? 
Obviously, what did you change? =)

[Polymax]

Interesting. What's about the noise on the chrome spotlight, on the top-right side of the brown ceiling? 
Obviously, what did you change? =)

ok. i try crop render of chrome spotlight!
I slightly changed the render settings.
Tonight I will render in high resolution, tomorrow will show the result :)

[cecofuli]

Can I ask you what parameters did you change? MSI? Lights samples?
Is the DOF off? Why?

[Polymax]

I reset renderer to default and changed:
1. Exposure compens = 4
2. Highlight comp = 5
and that's all :)
Well I need more time to achieve the best result, so tomorrow I will see what should be changed more (after hires render) :)

[cecofuli]

Only these? Mmm... I have to try me too =)

[Polymax]

I'll have to test with your scene, but now the result is:
What do you think?
PS. I use the method of solving the problem "step by step", so while rendering without the DOF! ;)

[cecofuli]

Good, but, as you can see on the chrome lamp, after 4 hours, still very noisy. Can you share your renderer setting by a screenshot?

[Polymax]

I tried to explain in the picture:

[cecofuli]

So, you suggest me to replace the real CoronaLights with Mesh + CoronaMtl emitters? Ok, I'll try...

[Stan_But]

So, you suggest me to replace the real CoronaLights with Mesh + CoronaMtl emitters? Ok, I'll try...

light mesh emitters are very noisy now. As and very many lights too.
Corona lights + coronaconstant mat will help you get out from noise

[maru]

Try this:

PTS: 24
LSM: 1


HD CACHE:
PT SAMPLES: 1024
pos sensitivity: 10

refl glossiness threshold: 1

Region-select a small square with lots of noise and render.

[Ondra]

it is not that simple, you will get different results (noise-wise) when rendering small region/entire picture with HD cache - small region will not properly fill the cache.

[cecofuli]

Try this:

PTS: 24
LSM: 1


HD CACHE:
PT SAMPLES: 1024
pos sensitivity: 10

refl glossiness threshold: 1

Region-select a small square with lots of noise and render.

Hi maru,
ok, I'll try a 1080p resolution tonight ;-)

[maru]

it is not that simple, you will get different results (noise-wise) when rendering small region/entire picture with HD cache - small region will not properly fill the cache.

This explains a lot. :)

[cecofuli]

Nothing to do...
With LSM: 1 I have a lot, a lot of noise coming from the arealight (areashadows)
Much better with LSM = 20 or 30.
The noise in the glossy surface, there lights are reflected still here.
After many test, I think the "solution " in to wait Ondra ;-)