Interior Scene noise issue - HDR Lighting

Hi Everyone,

I am back to learning blender after 6 years, so i am still new to the program, but i have been working professionaly as a viz artist using 3ds max and vray for at least a couple of years noe, so i am not a strander to the 3D world. Anyway, enough ranting.

I started experimenting with cycles a couple of days ago. and i took a similar approach to lighting as the one i am used to, lighting with only an hdr.

at first i used an unblurred version, i got heaps of fireflies.

then i used a blurred version, fireflies gone, but the problem is the noise. and simply bumping up the samples does not solve it. Even at 2000 samples. so another online search suggested that the hdr is actually not emitting enough light, and a sun must be used.

so i did that, and as i expected, the noise is not gone. So my question is this: How well Does cycles handle natural lighting?

Attached are two images, one only lit by an HDRI, the Other has combined hdr and sun lighting.

Any help would be greatly appreciated.

Workstation Specs:

Core i7 4930k six-core 3.9Ghz OC
nVidia GeForce GTX 760 4GB OC
16GB DDR3 2400MHz - Dual Channel
Dual 24 inch HD Monitor Setup

Attachments



Hi, it is more important how the light come in the room.
If you have only one windows it is very hard to handle with Cycles.
Can you post a screen shot from the room in wired view or better post the file > http://www.pasteall.org/blend/ with packed textures.
I think we only need th chrome parts, delete the other seat parts if the file is to big.

Cheers, mib

try to reduce the total bounce light to 4 or less and clamp indirect light

Thank you for the reply.

here is the blend file : “http://www.pasteall.org/blend/34018

Upon File Inspection, you will find that the model has sufficient opening to solid ratio. Again thank you for the help.

Cheers, jo

Thank you for the post.

the way i have read online is that total bounces only solves slow render times, and if anything, more bounces would contribute to less noise, not more. because more bounces means more illumination quality. Or at least that’s how other render engines work.

as for clamping, everything i read online suggests clamping for cases where fireflies are present, which is not my case.

again, your help is much appreciated.

cheers, jo

It also seems as if all bump maps (especially on the black sides of the chair) are waaay too strong…

Do you have MIP (multi Importance sampling) checked for the HDRI image in the world settings?

thenk you for the pointer.As i am still experimenting with materials, the way is long to go.

but i dont think that is the problem, as the white wall has no bump at all, and contains heaps of noise.

cheers, jo

yes, checked on both the sun and the hdri in the world.

cheers, jo

Hi, play some time with your file, 2000 Samples, Caustics off, indirect clamp 5, rendertime 5 minutes:


I have added a mesh emitter at the top of the room with low energy, kick noise and voronoi texture from the materials.
I don´t understand your environment node setup, btw. :slight_smile:

http://www.pasteall.org/blend/34030

JPG messed up my image:

http://www.pasteall.org/pic/82871

It is still noisy but 30 minutes to a few hours are not much for indor render.
Maybe other user can do better with branched path for example.

Cheers, mib

Mib asked me to take a look.

Lots going on here.

Unplug any materials that are using the “Displacement” output socket. It doesn’t work. You’ll need a displace modifier on those objects if you want real displacement.

The complicated world shader isn’t doing any favors to your noise. Different bounces are being treated differently by the integrator. If you’re going to play with setups like this, try to keep differences only to camera vs. secondary. Having different values for glossy, diffuse, transmission, etc. is just going to cause problems as the integrator tries to clear up the scene. The same with all of the color adjustments between different shader types. There’s really no obvious reason to try to tweak the HDRI to get an effect that you should be doing in post anyway. The visual difference between your setup and simply feeding in the image set to “non-color” for floating point and your setup is imperceptible. The time and noise differences, however, are huge.

On top of that, you have a scene that’s both very difficult to light with a unidirectional path tracing in general, plus caustics turned on, plus glossy materials creating those caustics. Caustic contribution in a scene like this will be next to nil. Turn caustics off, and turn filter glossy up as well, then clamp indirect as needed.

Finally, I’m not sure what the size of the HDR is because I didn’t check, but the map resolution should equal the length of the longest side of the HDRI for optimal importance map generation.

You could get render times down even more with Branched Path, but for a still it’s not really necessary.

Two minute render:


As for some basic material advice, glossy and diffuse on the floor and skirting for example should always be based on fresnel or facing rather than a constant value if you want to keep things relatively accurate.

also drop down all material values to a maximum of 0.8

mib, thank you very much for your help, as well as asking m9 to take a look.
the help is very much appreciated.

cheers, jo

m9, thank you very much for your help.

i am currently out of town, so it would be a couple of days untill i can actually try these recommendations. very helpfull information.

couple of pointers though:

1- thank you for clearing up the issue of displacement, i did not know the fact that i doesnt actually work. however my aim was to get a decent bump instead of displacement, and did not find a bump slot any where, only a normal slot, so i am assuming now that the bump and normal are interchangeable, am i right?

2- the editing on the hdr was simply to boost the contrast of it. the way that hdr’s work in other render engines is by sampling the luminosity of pixels in 32 bit space and treating those values as light rays, so boosting the contrast would result in stronger shadows and highlights, and the node group is just something i found online that seemingly did exactly what i was aiming for. my workflow is usually illuminating interior scenes with only an hdr with boosted contrast. is this workflow impossible to acheive using cycles?

3- i am surprised that my scene is hard to illuminate, the solid to void ratio is well beyond good to illuminate the room in real life, and as far as i know, what works in real life should pretty much more or less work in pbr (physically based rendering) workflows, and it pretty much does for me outside of blender. if you could point me as to what exactly is making the scene hard to illuminate with only unidirectional lighting and light bounces, i would be grateful.

4- about the fresnel, i knew these fact but did not know how to achieve it in blender. thank you for reminding me that this issue has not yet been solved on my part though.

finally, the reason i mention my workflow a lot is because i am trying to achieve similar results in order to convince my firm to make a switch to blender, not to brag but to try and get to the root of the problem.

again the help is much appreciated.

cheers, jo

1 - Under Add > Vector > there is indeed a Bump Map node. If you need bump and normal you can just feed the normal map node into the bump map node and then into your shader.

2 - Upping the contrast should help with shadows, but there’s no need to use that very complicated node group. Just throw a Brightness/Contrast node in between the image and Background nodes in the world settings.

3 - Interiors are always difficult for a unidirectional path tracer. With the changes Mib and I have suggested it’s not nearly as bad in terms of noise, but without any illumination inside of the room, expect long delays for indirect diffuse noise to clear up. This is mostly due to the fact that, on average, a ray shot from the camera in this scene will likely NOT hit a light source on its first or second bounce.

4 - Fresnel is located under Add > Layer Weight or Add > Fresnel (I personally prefer Layer Weight since Cycle’s Fresnel value is an approximation, and I like the artistic control of just using “Facing” + a color ramp better).

It would be great if you could get your firm to switch to Cycles, I won’t lie though: there are better choices for Archviz seeing as Cycles was designed for character animation (thus the issues with interiors and whatnot). That’s not to say Cycles can’t create great interiors and arch renders, but there will most definitely be a learning curve. May I ask what they currently use?

I currently use v-ray and 3ds max, the firm has been using sketchup and vray for a while, but since my employment i managed to convert them to 3ds max and v-ray, and needless to say, we manage to get hyper-realism out of v-ray pretty easily. but the open source nature of blender offers so much more flexibility. And i found it a robust platform for modeling so far. You seem to have other suggestions for render engines other than cycles?

If you already own licenses… You have VRay for Blender. Check Chaos Group Forums. They are of great help.