Arnold for 3ds Max - noise and general rendering questions

Daniel91

Hello all

working on a sci-fi hallway scene that will probably end up just being a wallpaper (not sure if that's relevant or not)

I'm very knew to rendering, so this is serving as my learning the basics and experimenting project

I have a few questions and I will post some renders at the end (they are mostly low res as the renders are taking a really long time on my pc and its making it hard to experiment)

1* Is clamping the main way to reduce fire flies? I have been experimenting with adding some atmospheric scattering and its making some horrible fireflies, but clamping doesn't seem to be helping

2* Is noise normally only found in the diffuse and specular? (i don't have any translucent objects so i think that rules out transmissive noise?

I'm pretty sure i have more questions than that, but i'm currently drawing a blank

I think this is looking pretty good, but i'm confident it could be better

(I have a few different renders, but sadly i was too dumb to think about saving the settings for each one........)

the following are all with atmospheric scattering off, as i haven't had the time to render that out yet


This one is looking good, i think. this took me 52mins to render.... I have some AOVs for it, but they dont actually show anything on them, so no sure what happened there
settings


The next lot are my most recent ones, again they look pretty good, but could be better (i have a heap of AVOs for this one, but they dont really show much so i wont upload them, unless there is one in particular that you want to see)

clamping was set to a value of 2

all the lights were set to 15 samples

I had to drop the resolution to get it to render in a decent time, but it will get upped for the final render, once im happy with everything

This was test number 25, only took 33mins this time



thanks for any tips and advice you can offer

Eric Chadwick

Not a lot of offline rendering done by most users of this forum. I would suggest posting this in the Autodesk official forum, to get the most informed feedback.
https://forums.autodesk.com/t5/3ds-max-shading-lighting-and/bd-p/area-b30

musashidan

The best workflow is to add AOVs for direct/indirect diffuse/shadow/spec. This way you can isolate the passes and see exactly where you need to increase samples so you not unnecessarily adding samples and render time in areas that don't need it. I HIGHLY recommend doing this. This is a balancing act to reduce noise and render times. Remember that the Camera AA is a multiplier on all other samples(including lights) You can evaluate the AA samples in the alpha channel.

For atmospheric effects you need to increase the samples in the Atmosphere Volume shader to reduce the noise.

As for clamping, this is generally the go-to for fireflies(Arnold does this automatically at very high ranges) Note that this will diminish the value range if you intend to do post work. This doesn't seem to be your case though as fireflies are most often caused by very bright light sources(including bounce light) reflecting off glossy spec surfaces.

Are you using IBL indirect lighting? If so, blurring the map and upping the resolution setting in the light(not the map) will help.

Where your corridor cuts off behind the camera there is complete blackness. You can add an area light portal facing back into the scene(behind the camera) for more illumination/bounce light realism. This may help reduce some noise.

Are you using exposure control? Try to use this instead of just cranking up the lights and getting local value blowouts at the light sources.

Basically, dimly lit interior scenes are your worst nightmare in noise reduction. That's why other renderers like Vray and Mental ray have non-brute force secondary tracing methods to fake/smooth the noise-free effect. Arnold doesn't do this though, it's a 100% brute force path tracer and is physically accurate. Your scene is particularly difficult to reduce all that noise because of this. There are methods to render passes for compositing and use noise-reduction filter tools in post on each pass.

Also, unrelated, but I highly recommend beveling/chamfering all those sharp 'CG' corners as it will drastically improve the realism.

gnoop

I just switched to Octane for any offline rendering . No problems with noise/sampling since especially after Nvidia denoiser.  Tried Arnold out of curiosity  several times and haven't found anything worth digging into

musashidan

@gnoop I've just started testing Arnold myself - using MR then Vray then Corona for years - my main reason being the new SSS randomwalk 2 skin shader.

Have you tested the Octane Skin shader and what DCC are you running it on? Also, how is Octane's Displacement?

Daniel91

Thanks all!

musashidan said:

The best workflow is to add AOVs for direct/indirect diffuse/shadow/spec. This way you can isolate the passes and see exactly where you need to increase samples so you not unnecessarily adding samples and render time in areas that don't need it. I HIGHLY recommend doing this. This is a balancing act to reduce noise and render times. Remember that the Camera AA is a multiplier on all other samples(including lights) You can evaluate the AA samples in the alpha channel.

For atmospheric effects you need to increase the samples in the Atmosphere Volume shader to reduce the noise.

As for clamping, this is generally the go-to for fireflies(Arnold does this automatically at very high ranges) Note that this will diminish the value range if you intend to do post work. This doesn't seem to be your case though as fireflies are most often caused by very bright light sources(including bounce light) reflecting off glossy spec surfaces.

Are you using IBL indirect lighting? If so, blurring the map and upping the resolution setting in the light(not the map) will help.

Where your corridor cuts off behind the camera there is complete blackness. You can add an area light portal facing back into the scene(behind the camera) for more illumination/bounce light realism. This may help reduce some noise.

Are you using exposure control? Try to use this instead of just cranking up the lights and getting local value blowouts at the light sources.

Basically, dimly lit interior scenes are your worst nightmare in noise reduction. That's why other renderers like Vray and Mental ray have non-brute force secondary tracing methods to fake/smooth the noise-free effect. Arnold doesn't do this though, it's a 100% brute force path tracer and is physically accurate. Your scene is particularly difficult to reduce all that noise because of this. There are methods to render passes for compositing and use noise-reduction filter tools in post on each pass.

Also, unrelated, but I highly recommend beveling/chamfering all those sharp 'CG' corners as it will drastically improve the realism.

thanks heaps mate,

I have rendered out some AOVs but they arent actually showing much.

When I add atmospheric volume I get a lot of fire flies, or at least what looks like fireflies to me, but clamping doesnt seem to help, so maybe it isnt actually fireflies

I am not using IBL indirect lighting, all of the lighting is coming from arnold mesh lights

I will experiment with the light portal.

do you mean exposure control in the camera? I have just been using the exposure and intensity inside the light itself, perhaps this is causing some problems? ill have a play

Most if not all of the edges have a chamfer on them, but maybe i need to exaggerate it a bit more as i kept them fairly tight.

I will have a play with all these things and see what I come up with

thanks heaps

musashidan

Yeah mate, you should add some IBL, even at a low level. The lack of light is the cause of so much noise. Did you raise the samples in the Atmosphere Volume shader?

The AOVs should show you exactly where the most noise is coming from and how much raising the samples is effecting the noise. Maybe you could post screens of your AOVs?

Fireflies, as I mentioned above, are primarily caused by very bright light sources reflecting off high gloss surfaces, so that shouldn't be a problem in your scene.

Using camera exposure control just means you can control it globally rather than in each light and rather than cranking up all your lights to compensate for low exposure.

The best way to think about this is as a real-world photographer. Imagine trying to get a noise-free image in such an environment with a real camera.

Daniel91

musashidan said:

Yeah mate, you should add some IBL, even at a low level. The lack of light is the cause of so much noise. Did you raise the samples in the Atmosphere Volume shader?

The AOVs should show you exactly where the most noise is coming from and how much raising the samples is effecting the noise. Maybe you could post screens of your AOVs?

Fireflies, as I mentioned above, are primarily caused by very bright light sources reflecting off high gloss surfaces, so that shouldn't be a problem in your scene.

Using camera exposure control just means you can control it globally rather than in each light and rather than cranking up all your lights to compensate for low exposure.

The best way to think about this is as a real-world photographer. Imagine trying to get a noise-free image in such an environment with a real camera.

That exposure control analogy makes it so much clearer, cheers!

From memory I did experiment with the samples in the atmosphere shader, but I cant actually remember 100% so ill have a bit more of a play with that one

the following renders are using camera exposure rather than adjusting the lights themselves, I havent had chance to try anything else yet

The AOVs i rendered for this are actually completely black, i think i must have done something wrong, as that doesnt make sense at all to me


This one below should be diffuse direct.....

musashidan

I just noticed that you said you used mesh lights. Is this actual mesh lights or a mesh with an emissive shader? I ask because the emissive shader requires very high sampling to clean up as opposed to the mesh light.

Keep trying with the AOVs. This is key to understanding where the noise is coming from.

Daniel91

Its an actual mesh light using an Arnold light, the mesh does have a very small emitter value on it, to make it visible in the render

going to try have another play with the AOVs today.

i did a bit of playing in a more basic scene yesterday to see if i could work out how the atmosphere shaders worked, but i think ill forget about that until i can get the render sorted with out it

Daniel91

Ok, here is another crack, the AOVs seem to have actually rendered this time.

I added a skydome light with a HDRI map on it,

the yellow and red light at the end is an emmisive, so i may try swapping that out for a proper mesh light




Diffuse direct 

diffuse indirect

emmision

specular direct

specular indirect

musashidan

I can see straight away that your specular indirect AOV has the most noise. Did you up the skydome samples?

Daniel91

musashidan said:

I can see straight away that your specular indirect AOV has the most noise. Did you up the skydome samples?

just checked and it was set to 5, iv upped it to 15 and will do another render

im going to fix the lights at the end as well

iv also adjusted some exposure levels around, as i forgot to do them before

just waiting for it to render

Daniel91

This one took almost 2 hours

looks like there is a bit of noise in the diffuse indirect and a whole but load of it in the specular indirect, specular direct looks pretty clean tho

all of the lights were set to 15 samples 

to fix the specular indirect, do I just need to crank up the specular samples? (thats what the documentation seems to say)

(just noticed how bad the texture is on the bulk head roof support thingys, will fix that before next render)





diffuse direct

indirect

spec direct

indirect

musashidan

Yeah mate, it's just a matter of raising the spec samples and maybe lower your diffuse samples and increase the camera samples(not by too much as it's a global multiplier)

Another thing you could try is raising the low light threshold to reduce the render time.

Are you using a .HDR in the skydome light? If so, did you raise the resolution within the light?

This is just how it is with unbiased brute force rendering: Noise Vs render time.

What hardware are you on?

Daniel91

musashidan said:

Yeah mate, it's just a matter of raising the spec samples and maybe lower your diffuse samples and increase the camera samples(not by too much as it's a global multiplier)

Another thing you could try is raising the low light threshold to reduce the render time.

Are you using a .HDR in the skydome light? If so, did you raise the resolution within the light?

This is just how it is with unbiased brute force rendering: Noise Vs render time.

What hardware are you on?

is this what you mean by the resolution? and yes, it has an HDR on it
 

what hardware is relevant to this? (im not tech savvy) these are my specs, Im thinking an I5 and only 8gb of ram isn't great

I also have a gtx1060 gpu, but i dont think arnold uses gpu for rendering?

gnoop

musashidan said:

@gnoop I've just started testing Arnold myself - using MR then Vray then Corona for years - my main reason being the new SSS randomwalk 2 skin shader.

Have you tested the Octane Skin shader and what DCC are you running it on? Also, how is Octane's Displacement?

Octane doesn't have specific skin shader, just a "Universal" PBR one where you could set extra coating and shin layers with its own IOR and roughness and have pretty realistic light transmission/sss effects.  Although I had to admit I use it mostly for landscape things.   It's a tad  less realistic   regarding the skin matter  than I have been  able to do elsewhere  but imo the difference is very marginal and probably I just haven't set it right. Same with grass/trees . They looks just a little bit more simplistic in regards of the light transmission through the foliage than I able to do with Clarisse for example, a very Arnold like render.   But that's again maybe just me who didn't do it right.       But it's very little to setup there actually. Overall It's pretty simple.

I use it with Blender and Max plugins.    It's very well done for Blender  with only lacking thing is absence of Proxy objects in Blender.   In Max there are proxies, a very efficient way for huge scenes but it's imo kind of clunky there  with MAx particle flow.    In Blender the current version  started to works ok with its hair/particle based  style of scattering. Not as instant as Clarisse on super huge scenes  but still better visual feedback.

One annoying thing in Blender although is that it loses its connection to Octane often and needs to be reopened. And of course the main limitation is video memory. It needs a lot of video RAM for big scenes. It's a main problem.

As of displacement  it's super cool and easy there. To be honest it's one of the best thing in Octane IMO  and it does a true displacement  not Arnold styled  low res one + bump map.  Kind of important thing for height map baking.      

Daniel91

Ok, 29th times the charm? not really. specular indirect is a tiny bit better, but i think im going to need to crank up the samples even more

For this one i dropped the diffuse a little bit and raised the specular samples and the ray depth, I also upped the low light threshold by 5 times

the diffuse looks ok despite dropping the samples a bit

this one took 3hours 20 mins (with 3dsmax using 97-99% of my cpu the whole time) I'm not looking forward to trying to render a high res one at the end of this....

Ill save some time and only post the specular diffuse AOV this time, as the rest looks ok to me

Prime8

I only have experience with Cycles and Octane, therefore I'm not sure if some of this general advice, to avoid noise and fireflies, apply to Arnold.

- Try to avoid very small bright lights, e.g. don't make the wire in a bulb highly emissive, rather emit light from the bulb itself
- Reflective and refractive caustics can be filtered, clamped or completely turned off 
- Very glossy and refractive materials cause caustics, sometimes you are better off with "fake glass" or less glossy materials
- For a room lit by an outside light source portal should be utilised
- Rooms without an outside light source should be closed

Or course this is all very much depending on the scene.
Can you show the mesh of your lights? Is it not possible to utilise your GPU for rendering?

Daniel91

Prime8 said:

I only have experience with Cycles and Octane, therefore I'm not sure if some of this general advice, to avoid noise and fireflies, apply to Arnold.

- Try to avoid very small bright lights, e.g. don't make the wire in a bulb highly emissive, rather emit light from the bulb itself
- Reflective and refractive caustics can be filtered, clamped or completely turned off 
- Very glossy and refractive materials cause caustics, sometimes you are better off with "fake glass" or less glossy materials
- For a room lit by an outside light source portal should be utilised
- Rooms without an outside light source should be closed

Or course this is all very much depending on the scene.
Can you show the mesh of your lights? Is it not possible to utilise your GPU for rendering?

Hi mate, thanks for the tips

most of my mesh lights are large-ish, (not as small as the filament of a bulb at least)
I have gotten rid of most if not all of the very glossy surfaces, as I'm going for that dirty grungy scifi look with it, so i think i have cut down on the majority of that.
what if its a room with an inside light and an outside light? at the moment i do have a sky dome light, but not utilizing a portal 


I can post a pic of the meshes for the lights after my current render, but they are all pretty simple;

the ones along the bottom are just planes, and the ones higher up are just simple 8 sided cylinders

there are a couple at the very end of the hallway that are semi spheres 

I did some half assed googling and it looks like arnold for max doesnt support GPU rendering yet,

Daniel91

Prime8 said:

I only have experience with Cycles and Octane, therefore I'm not sure if some of this general advice, to avoid noise and fireflies, apply to Arnold.

- Try to avoid very small bright lights, e.g. don't make the wire in a bulb highly emissive, rather emit light from the bulb itself
- Reflective and refractive caustics can be filtered, clamped or completely turned off 
- Very glossy and refractive materials cause caustics, sometimes you are better off with "fake glass" or less glossy materials
- For a room lit by an outside light source portal should be utilised
- Rooms without an outside light source should be closed

Or course this is all very much depending on the scene.
Can you show the mesh of your lights? Is it not possible to utilise your GPU for rendering?

Here are the meshes that are used for lighting (they arent this close to each other in the actual scene)

musashidan

Your machine probably only has 4-6 cores? Not great for brute force rendering. Latest Arnold core is GPU ready.

You do know that you can use gobo textures on area lights to simulate the shape instead of mesh lights?

Just keep cranking those samples.

Daniel91

musashidan said:

Your machine probably only has 4-6 cores? Not great for brute force rendering. Latest Arnold core is GPU ready.

You do know that you can use gobo textures on area lights to simulate the shape instead of mesh lights?

Just keep cranking those samples.

4 cores according to google,

i dont know what gobo textures are, so i will have a look into that

musashidan

Sorry mate, but 4 i5 cores is pretty terrible. Look into upgrading to the latest Arnold core and try the GPU. Your 1060 might fair better.

Prime8

For testing at least, try to reduce the light meshes, 8 sides on a cylinder doesn't sound like a lot but it can make a difference, especially since you have more than one of them.
At least I would remove the face lighting backwards, if the design allows for it. 

Can't tell how small the spheres are from that screenshot, though I cannot see them in the scene, therefore I guess you can simplify them as well.

gnoop

Does Arnold GPU really work?      I tried and waited for result forever  . Seems same slow as CPU.

ps. Well , test renders shows it's quicker , slightly .          But comparing to Octane it's not even  comparable.    

Also  does somebody know how to make Nvidia de-noiser work in Arnold for MAx?     In Octane it's super efficient and in Arnold  3.0.77  I see the checkbox but doesn't see any  post render denoising at all  in  Max2019 

Daniel91

musashidan said:

Sorry mate, but 4 i5 cores is pretty terrible. Look into upgrading to the latest Arnold core and try the GPU. Your 1060 might fair better.

Yeah, when i built this pc i didnt plan on using it for this  

what would you recommend? i cant afford one now, but I can start saving up

my 1060 only has 3g of ram, so im not sure how well it will cope, but i can have a play

Prime8 said:

For testing at least, try to reduce the light meshes, 8 sides on a cylinder doesn't sound like a lot but it can make a difference, especially since you have more than one of them.
At least I would remove the face lighting backwards, if the design allows for it. 

Can't tell how small the spheres are from that screenshot, though I cannot see them in the scene, therefore I guess you can simplify them as well.

Thats a really good idea, i hadnt thought of that

the 2 small spheres go on the door at the end, to the right of the big yellow one. they are meant to be adding a little bit of red light at the end of the hallway, i hadnt even noticed they arent showing up

Daniel91

musashidan said:

Sorry mate, but 4 i5 cores is pretty terrible. Look into upgrading to the latest Arnold core and try the GPU. Your 1060 might fair better.

Been doing a bit of research and i cant really upgrade my cpu much without doing my motherboard as well, so that isnt going to happen any time soon

iv been playing with the gpu renderer though and will post some up when i get something a bit cleaner,

seem to have a lot less control with the gpu renderer, or is that just me?

musashidan

GPU only uses the Camera AA samples. Turn on Adaptive Sampling, set the Max to 100 and lower the noise threshold to clean the noise.