Irradiance Map min max rate

[Dink]

I would know, for better render how i must set the min and max rate of IM?

MIN RATE , lower (negative) values better render? Or higher values do better render?

MAX RATE? lower (negative) values better render? Or higher values do better render?

[dalomar_cg]

Re: Irradiance Map min max rate

Min and Max rates are something to be thought of together, not alone, since its the combination of them that will set the over all result.

Max rate is going to be the most important one, and essentially, the closer that number is to zero (or if it goes positive) then the "more quality" it will have. That being said, once you get to those levels, you'll get less and less noticeable difference between the results...ie going from a max rate of -3 to -2, you'll probably notice a significant difference. Going from -2 to -1, will be noticeable, but only in detailed parts of a scene. Going from -1 to 0 is going to be barely noticable, and even so only in the most detailed parts of the scene.

Min Rate's role in the party is mainly to manage adaptation and the solution density. Adaptation is something that is desirable within a V-Ray render because that makes things faster, but too much adaptation will tend to introduce artifacts and too little adaptation can sometimes cause more artifacts then needed. Ultimately, the desired number of prepasses (which will be determined by the "distance" between the min rate and max rate) is between 3 and 5. Any less than that, and you're typically looking at too dense of a solution and too more than that and you're looking at solutions that may be plagued by extraneous samples.

Thats really the basis for setting min/max rates. Here's a few guidlines from setups that I tend to use.

Usually for tests and general usage (ie for myself and for quick drafts) I tend to use a min/max rate of -4/-2...the max rate gives me a decent quality without it being overly detailed or lacking detail...the min rate of -4 gives me just enough adaptation (3 prepasses) but not so much that I'm not getting good coverage (remember I'm only sampling to -2).

As far as final quality and IR I'll typically lower my Max rate to -1. Personally I don't see much benefit to go lower than that when comparing the results to the time taken to calculate, and most of the people I suggest this too tend to agree with me on this. As far as min rate I might leave that at -4 or bump it down to -5. That will give me enough flexibility for the calculations to go without too much of a slow down.

Keep in mind that these are all for screen resolutions, so any thing that is beyond 800-1000 pixels typically needs some extra consideration. IR at higher resolutions is something that needs to be managed correctly as IR will not act the same.

HTH

[Micha_cg]

Re: Irradiance Map min max rate

Last we talk about it here:

http://asgvis.com/index.php?option=c...0&topic=3504.0

Interesting for me was, that a large step between min and max can be usefull to speed up the rendering and get less large area blotches. Personaly, most I don't fiddle about min/max and disable multipass and use -2 (large images), -1 (small images medium detail quality) and 0 (high detail quality good for small images with little details).

[Dink]

Re: Irradiance Map min max rate

and what about multipass?

multipass enabled better quality?

[Dink]

Re: Irradiance Map min max rate

i'm rendering a car, i have problem with the space between the parts.



I must increase the max rate? the antialising? mmmmm

[Micha_cg]

Re: Irradiance Map min max rate

Multipass ... is it not discuss at the linked post?

Antialisasing - if IM GI is the problem, than detail enhancement (IM option) could help. But also a light blur filter at the image sampler could help - f.ex. area 1.3 .. 1.5 or render a higher resolution.

[dalomar_cg]

Re: Irradiance Map min max rate

Multi pass doesn't change the quality, it simply renders the IR map in one pass as opposed to however many number of prepasses are needed.

When you start getting into details like on the car, then you start entering the world of Detail Enhancement (DE). DE is a hybrid calculation method that will use IR for most of the calculations, but when there is really tight details, DMC calculations will be used. This is really powerful for times when there are large flat areas that don't need the detail of DMC and very detailed parts that cannot be done well with IR so they really need DMC.

[Dink]

Re: Irradiance Map min max rate

ok good, i enable DE

i leave the default DE settings... not?

[dalomar_cg]

Re: Irradiance Map min max rate

Check out this link as it will explain what the DE settings actually do.

http://www.spot3d.com/vray/help/150R...map.htm#detail

I tend to lower the radius a bit to about 40 pixels. AFA setting the subD multiplier, remember that the actual number of samples will change with the number of HSph SubDs that are taken. I try to make sure that DE will take about 8 subDs (which is the standard for DMC calcs. So @ the default of 50 hsph SubDs, the DE subD multiplier would need to be at .16 for 8 Subds or a good round .2 for 10 subDs.

[Micha_cg]

Re: Irradiance Map min max rate

Damien, since IM and QMC noise are totaly different looking, couldn't it be good to get direct DE subdiv control? I don't understand, why DE subdivs are relativ to IM subdivs, the user must calculate the right amount. I suppose so, Joe could easy change the UI.

[dalomar_cg]

Re: Irradiance Map min max rate

Yea, thats not a question for me, but really one for Vlado. We try to keep UI consistent between Max and Rhino, so I doubt we would simply change that on our end.

For me at least, setting DE is a pretty deliberate act, so figuring out the correct multiplier (which is a 5 sec thing anyway) isn't too bad. The idea behind the multiplier is that if you were doing tests, you could still use DE and wouldn't get a big hit if you had a smaller hsph subD, but when you bumped that up for final quality, then DE would be automatic as well. So in that sense it saves a step.

[Micha_cg]

Re: Irradiance Map min max rate

Hmm, for preview usage I use the global multiplier and set it at an value below 1. So I keep my optimized subdivs settings everywhere.
Right, 5 seconds are enough for me too - I think on the new users, who must learn all this dependencies. If once a day Vray will be optimized for simplier usage, this option could be at the list.

[dalomar_cg]

Re: Irradiance Map min max rate

Well DE isn't for the simple...its usually part of a more complex IR setup. I don't think DE would make it into anything less than an advanced UI.