Cheatsheet: How to get a Cleaner image with SP3

[jneilon]

Hi Lele thanks for posting,
What was the image size of your tests?

[^Lele^]

I suppose a default 640x480.
Make sure you download the full-size cheat-sheet from the gDrive link. the forum one has been resized.

[peterletten]

Hi Lele,

Thanks for all the info - much appreciated.
Re IR vs BF, you mentioned BF has sped up a lot in VRay 3.3.... but we're still looking at at least 4-5 times longer renders correct?

Typically I find I get 4k images rendering around 3hr mark using IR & LC. Which is just about allowable in my production environment, but 4-5 times this time isnt an option for me. I have one machine in the office, (I use online rendering for big/tight productions but this comes with its own headaches, particularly here in Australia with our 1Mb upload speeds...)

So my question is, in your experience, is my "4-5 times longer" correct? - is BF & LC still taking 4-5 times longer than IR & LC to get to a similar level of noise?

[vlado]

It depensds on what kind of noise level is acceptable for you and n the scene. I found that in many cases BF was just as fast if not faster to get a good image out (f.e. while the irradiance map was being computed, a progressive BF render already was looking quite good).

Best regards,
Vlado

[AndresAhumada]

Hi guys.

In short, how is the strategy to use HDRI map in the dome without much noise.? For now use local subdivisions is not a smart choice.
This really is giving me a headache.

Cheers

[notamondayfan]

Hello!

Just testing 3.3 and this new workflow, seems good to me so far.

Quick question 1, how exactly are the subdivs on materials and lights controlled? I used xref scenes at lot (essentially my scene file only contains cameras and lights), so is there an issue with materials not being adjusted if using xrefs? Or are the subdivs calculated purely at render time? Obviously in the past I'd have to adjust materials in the xref file, and refresh, but I'm hoping this is no longer the case. And also should we re-set the xref files, or are all render settings ignored when xref'd?

Quick question 2, when re-setting to defaults, the Min samples in Global DMC gets changed to 16, but would it wise to change this back to 8, as surely some materials / lights / etc won't need more than 8?

Quick question 3, I see this new workflow really tackling reflection noise well, but for me, light noise always seems to be grainier, and I have to lower the color threshold to get the noise to be acceptable, but is this over-doing the material subdivs?

Thanks,
Dean

[vlado]

Quick question 1, how exactly are the subdivs on materials and lights controlled? I used xref scenes at lot (essentially my scene file only contains cameras and lights), so is there an issue with materials not being adjusted if using xrefs? Or are the subdivs calculated purely at render time? Obviously in the past I'd have to adjust materials in the xref file, and refresh, but I'm hoping this is no longer the case. And also should we re-set the xref files, or are all render settings ignored when xref'd?

The subdivs are calculated at render time. There's no need to adjust anything in the X-Ref files.

Quick question 2, when re-setting to defaults, the Min samples in Global DMC gets changed to 16, but would it wise to change this back to 8, as surely some materials / lights / etc won't need more than 8?

Leave the default here

Quick question 3, I see this new workflow really tackling reflection noise well, but for me, light noise always seems to be grainier, and I have to lower the color threshold to get the noise to be acceptable, but is this over-doing the material subdivs?

The adaptation is the same regardless if the noise comes from materials and lights, so ideally it should not be needed to adjust the noise threshold. I would be curious to take a look at any actual examples though.

Btw, as an R&D project we made an internal version of V-Ray that samples shading components (reflections/GI/lighting/refractions) completely separately from each other and can stop the calculations for components that are ready before the others are. The results were not very conclusive though...

Best regards,
Vlado

[AndresAhumada]

Any suggest?

[vlado]

Any suggest?

I don't understand your question. Dome light with HDRI works fine for me.

Best regards,
Vlado

[notamondayfan]

The subdivs are calculated at render time. There's no need to adjust anything in the X-Ref files.

Leave the default here

The adaptation is the same regardless if the noise comes from materials and lights, so ideally it should not be needed to adjust the noise threshold. I would be curious to take a look at any actual examples though.

Btw, as an R&D project we made an internal version of V-Ray that samples shading components (reflections/GI/lighting/refractions) completely separately from each other and can stop the calculations for components that are ready before the others are. The results were not very conclusive though...

Best regards,
Vlado

OK thanks Vlado, good to know about the xrefs and min sample value.

For the light noise, I perhaps need to look more at this, as typically the scene I'm using is very complex in terms of materials and lighting (a realistic section of an eyeball, lit with HDRI), so when I test on a more typical interior or exterior I'll be better to judge on the noise "issue".

Cheers,
Dean

[Alex_M]

OK thanks Vlado, good to know about the xrefs and min sample value.

For the light noise, I perhaps need to look more at this, as typically the scene I'm using is very complex in terms of materials and lighting (a realistic section of an eyeball, lit with HDRI), so when I test on a more typical interior or exterior I'll be better to judge on the noise "issue".

Cheers,
Dean

Is your noise caused by bright pixels? Since you're using HDRI, it's possible that it has some very bright portions or it's bright values are boosted by the gamma parameter in the HDRI map. This can make reflections pick very bright rays from these bright parts of the HDRI. See if the problem with the reflection noise still exists if you turn on "Max ray intensity" and set it to 20 or thereabouts. Don't go very low since it's going to "decrease" the dynamic range of your images.

[notamondayfan]

Is your noise caused by bright pixels? Since you're using HDRI, it's possible that it has some very bright portions or it's bright values are boosted by the gamma parameter in the HDRI map. This can make reflections pick very bright rays from these bright parts of the HDRI. See if the problem with the reflection noise still exists if you turn on "Max ray intensity" and set it to 20 or thereabouts. Don't go very low since it's going to "decrease" the dynamic range of your images.

Max ray intensity is already ticked and at 20 (default setting right?) To be honest the noise is pretty constant over the model, to me it could even be GI (BF) noise.

[Pixelab]

I don't understand your question. Dome light with HDRI works fine for me.

Best regards,
Vlado

I think I see the issue, I have more or less the same. Before SP3, it was possible to increase subdiv of the dome HDRI use in direct light for only a small increase in render time. (see PG post, point 8 to illustrate http://www.peterguthrie.net/blog/201...-for-interiors ) Now, you just can't, and the noise of the HDRI is too noticable when working with IR allowing higher noise thresold (and thus faster render times).

If you lower the noise thresold for the whole scene like it's advised, the render time increases too much (and bascially the use of an IR for speed is then worthless, like you said in another post)

I made some tests and swtching back the HDRI into the IR worked good so far, but for IR user it's a step back

[VelvetElvis]

I'm trying to wrap my head around the new update without actually using it. We haven't rolled it out yet, but I want to be prepared as we'll probably roll it out in mid production as we don't have a lot of downtime these days.

Would you say that it's best to stick with progressive and BF now with SP3? For the past few projects, I've been using IR with store with irradience map on a lot of my lights in order to get a bit of a render speed boost. Is that practice slowly going to the side now that Vray is getting this overhaul?

My typical render preset has been to leave all subdivs at 8, store with irradience maps on most lights, use IR+LC, min shading rate at 8, Adaptive at 1/24 and control my noise with the color threshold at .01. I found that for our threshold for noise, this would get use a practically noise free rendering in 1/4 the time than if we use 1/48 or even 1/100 and a color threshold of .005 to .008. How much different would an SP3 preset get?

[glorybound]

I would start with all defaults, except set the progressive engine to unlimited time and enable GI, all with defaults. You can lower the noise threshold, if needed and raise the AA, if needed. Use the VRaySamplerRate and if your noise is in blue, lower the noise threshold and if the noise is in the red area, raise the AA.