Understanding DMC Sampler

[Donald2B]

That would be greatly appreciated!

Thanks again for all the knowledge you share with us!

[Morne]

Ah okay - are you delivering print or animation for this? I'd go irmap for the print, the animation is a whole other world of hurt

For light cache the prefilter is okay, lele recommends using a pretty high value for this - around 250 I think? The filter drop down menu gets set to none. Retrace threshold on also.

Thanks for your help John (and others)

But clearly I must have messed something up somewhere, because I changed to IRmap and LC, and changes bunch of other settings, and rendered at 4K
However this time my pc (an i7 3930K with 32GB ram) and another 6 slaves like that, took 10 hours to render!!! (and RAWReflection still has noise) Beauty, GI and Sample rate looks great however.

Would love to revisit this and see what the pluk the problem was, but no time right now...

[joconnell]

It's a big juggling act alright and as far as I'm aware it's being worked on pretty intensively to make vray 3 easier to use. It's been shown with massive speed ups in brute force already and no doubt vlado will also get around to doing some light and glossy material optimizations too.

Raw reflection is kind of misleading since it's showing all of your reflections boosted up to full strength as if you were using a chrome material, so that could look totally perfect, but when you look at the regular reflection pass, which shows your reflections at the level they're added in to the final pixels with, you can start to see noise appearing.

[kosso_olli]

For light cache the prefilter is okay, lele recommends using a pretty high value for this - around 250 I think? The filter drop down menu gets set to none. Retrace threshold on also.

Could you please explain the theory behind it? Would like to try that myself, but I don't understand the concept...

[olly]

Colin senner wrote a great tool called VMC or vray material control which will likely give you a lot of at a glance info

Really? I will have to look that up!

[cheerioboy]

I've had quite some trouble with blurry reflections, after having balanced everything else in my scene (image sampler & light subdivs). I think I need to think more about how much I blur the reflections, especially when using maps. But now once everything is nice and smooth and slow to render, can I assume that dialing the noise threshold is the best way to shift everything quality-wise if I need faster previews of views?

[Donald2B]

That's what I do. I go into the system tab and set the DMC Noise threshold to 0.1 or 0.2. That usually gets my renders down quite a bit and I can still see what's going on in the scene. I also turn off the render elements which helps some too.

I just need to remember to set it back for the final rendering and turn on my render elements. It works great for me.

[Dariusz Makowski (Dadal)]

If u want quickly to lower quality just go to DMC settings and lower multiplier to 0.1

[joconnell]

Really? I will have to look that up!

My apologies, thought it was colin from memory!

[wyszolmirski]

This thread was great read a while ago, and extremely helpful. Now when 3.0 beta is out, and most of us probably tried it out. What do you think about using the min shading rate as your main secondary samples control ?

From my initial tests now it might be not a bad idea to just go with something like this: Adaptive 1/50, shaders, lights, brute force at default 8 + adjust only min shading rate. I will do some tests now.

[joconnell]

It's all still relevant. Brute force rendering has changed a lot, light sampling has changed a lot. Materials are still to be worked on in terms of glossy speed ups - let's see can we get vlado to go on another holiday

[peterguthrie]

I will do some tests now.

please do! very interested to learn more about this min shading rate thing..

[rikou]

+1 !
please ! please !!

I learnt so much from this thread !! Thanks a lot to all of you guys ! really big thanks
This min shading rate seems to be a great addition but also a mysterious yet today for me...
And when I see back all what I learnt from here, I'm pretty sure this mystery will not last long !

[wyszolmirski]

Ok, so I've tried to understand what's going on with min shading rate and as far as I understand it now it's basically how many Secondary Samples it will trace per Eye Ray (AA rays or Primary Samples).

In my tests it corresponds to "MAX Secondary Samples" in this calculator http://www.cggallery.com/tutorials/dmc_calculator/ . So if you have AA 1/16 and all your shaders set to 64, it should produce the same result as with all shaders set to anything up to 64 and Min Shading Rate at 16.

Cool thing about shading rate is that it's global, it's fixed and when you change max AA subdivs it won't be affected. I can see this as very useful tool for finding sweet spot by changing only AA and shading rate. This can be different for each scene.

Don't take this as a fact, there might be some other factors and it still needs deeper understanding. If you could test it out and give some insights it would be great.

[RockinAkin]

Coincidentally - I've updated the calculator to include the new Min Shading Rate parameter.

http://www.cggallery.com/tutorials/dmc_calculator/

Hopefully that helps illustrate it's functionality a bit... let me know if it's unclear still.