Any vray Wizard here ? help me

[fadi3d]

Hello guys i wonder if any of u would be so kind as to help me reduce the noise in this render and please explain why i always get the jagged edges

in the ceiling next to the indirect lighting ?

my Ir is high and Lc 1200 and aa Dmc 1-10 Clr Tresh 0.001

MAx 2008 Vray 1.5 Sp1

Thank u in advance and take care

[Brian Smith]

well your image sampler is no longer adaptive with that extremely low clr thresh value. because it's not, you are forcing 10 subdivisions for all your pixels and that will mean very, very long render times. i've made a lot of post about your problem...if you are interested, maybe do a search for keywords 'brian smith vray'

[fadi3d]

Dear Brian i am very pleased u answered so fast .in fact i admire u very much and i have collected almost every tutorial u made and was waiting for ur last book (wich i think is the time to order it) i wish there was more peple like u willing to help.

i suspected it could be the sampler and was (kind of )basing my settings on a tut Mr nichols did on Gnomon and the fact that vary people at Chaos say we rarely need to get the lower threshold to more than 1.well i might be understanding wrong and i will reread ur tut on sampling but meantime i wish u could elaborate more .by the way do u discuss vray advanced setting in ur book ?

thank u for ur time.regards

[Brian Smith]

thanks for the comments.

 

the problem with setting the min rate at 1 is, it's really impossible to tell vray when to use the higher values up to the max rate and when to use the min rate itself. when the clr threshold is set to 0.0, you are telling vray you want a perfect image sampler. that of course is not possible, so the only thing it can do is apply the max value everywhere. so for some areas, 1 will certainly be all that is needed, but in many other areas, 1 wont be nearly enough and the clr threshold is too general in nature to provide more flexibility in dictating which pixels get the lower values. forcing a higher min value causes a little extra render time, but it's well worth not having any undersampled pixels. as long as you dont drop the clr thresh too low, then you will be taking advantage of the min rate.

 

there is an appendix at the back of the book dedicated to vray btw.

[fadi3d]

Brian I don’t mean to trouble u but I want to get to the bottom of this issue.

First of all let me Clarify that I work in LWF and was using Adaptive DMC with a Clr Thresh of 0.001

(Not as u stated 0.0) If I understood u Wright (and please correct me if I am wrong) I should use a Min 3 Max 10 with a Clr Thresh of 0.001? Or should I also change the Clr thresh to a higher or lower number?

“so the only thing it can do is apply the max value everywhere” here u lost me (it might be my not so perfect English) but if all sampling is done at 10 this should result in better sampling and much higher render time than if one was done at 1 and the other at 10 ?

What I mean to say is in my case Vray is deciding depending on the color Tresh and has the ability to sample at 1,2,5,7 or the max 10 so it should be faster than A choice of 3 to 10 (no 1 or 2)SO:

-Do u mean vray’s Decision is Taking the longer time?

-then what will be the Difference Between Adaptive DMC 3-6 and Adaptive Subdivision 3-6 with the SAME clr thresh ?

Excuse me for asking but will ur method contrast with Mr Nichols (Vray speed Vs Quality)? Or each one is one way of doing things?

Note pls Specify Clr thresh in a number (I mean lower is it 0.1 or 0.001?)

I hope what I am asking is making any sense to you.

Again sorry for the trouble and thank u very much.

[Brian Smith]

please looks at some of the other recent posts i made. if you do and still have questions after reading them, i will answer them...but all of your questions would be answered in just a couple of previous posts.

[Dave Buchhofer]

I'm going to lay down a guess here, are you using the VraySun/Physical Camera.. if so, what is the multiplier on that vraylight up in your cove. pretty high I'd imagine. along with the mulitpliers you're using on the downlights to fake them into being visible in a full daytime shot where the camera is exposed to see everything.

 

anti aliasing (And really, anything that is using a randomized hemispherical shooting of rays to evaluate) gets slower/harder when there is a huge contrast in a scene, meaning its much harder to eliminate the GI noise that you are seeing on the left wall there

 

without adjusting your lighting you can improve the GI noise issue somewhat by turning up your HSPH Subdivs (Accuracy at each point) in the irradiance map by a LOT. and also you can raise the interp samples (Amount of Blurring at each point) to smooth it out some.

 

there's a lot of things wrong with the settings in terms of looking for pure speed/quality, but they're all sort of interconnected, for ex: cranking up your min/max in the DMC image sampler, and turning down the noise, will help to fight against the fact that you're trying to anti alias across a HUGE lighting value range, but it will also force your glossies and your light/shadow subdivs to go artificially higher than they need (ie: slowness past the point of visual return)

[fadi3d]

dave the multiplier in the cove is 30 (Vray Light Material ) as for the Ies they r left as is .yes VraySun/Physical Camera with Shuter 80 Iso 300.

Irr 50 Hsph 25 Interp.

at the suggestion of Brian i rendered a region with the same setting of Irr and Lc but used Ad Sub of 2 and 4 and a Clr Thresh of 0.01 wich gave me perfect results with no noise but at 30 min (the region not all the pic)

then again with Adap Dmc of 3 and 6 at 0.01 and it was noisy Albeit fast at 6.4 min

then again with Adap Dmc of 3 and 6 at 0.005 and it was less noisy and fast at 6.48 min but much worse than Ad Sub wich i think is weird.

and Brian i am still checking all ur posts an rereading ur tut on sampling(an indepth look at image sampling)

Thank u guys ur the best but i have still to crack this.

[Dave Buchhofer]

yea adaptive subdivision handles the glossies much differently, will generally get you a cleaner image overall, but can be a LOT slower than dmc on scenes where there is multiple types of glossy effects

[Brian Smith]

dave the multiplier in the cove is 30 (Vray Light Material ) as for the Ies they r left as is .yes VraySun/Physical Camera with Shuter 80 Iso 300.

Irr 50 Hsph 25 Interp.

at the suggestion of Brian i rendered a region with the same setting of Irr and Lc but used Ad Sub of 2 and 4 and a Clr Thresh of 0.01 wich gave me perfect results with no noise but at 30 min (the region not all the pic)

then again with Adap Dmc of 3 and 6 at 0.01 and it was noisy Albeit fast at 6.4 min

then again with Adap Dmc of 3 and 6 at 0.005 and it was less noisy and fast at 6.48 min but much worse than Ad Sub wich i think is weird.

and Brian i am still checking all ur posts an rereading ur tut on sampling(an indepth look at image sampling)

Thank u guys ur the best but i have still to crack this.

 

i don't recall ever saying to use adapt subdiv anytime before. if i did, please tell me where that post is so i can correct. adapt subdiv does not handle glossies well. i recommend only using adapt subdiv on test renders or scenes with large areas of smoothly shaded surfaces and no blurries.

[fadi3d]

sorry Brian what i meant to say was for the 2nd and 3rd render which i understood from reading the posts u've made which i read so far.

guys could u explaine why Adaptive subdive and adap Dmc work differently.i mean logicaly to me if i can get pretty impressive results with ad Sub at 2 and 4 i should get the same with Dmc at 2 and 4 with the same Clr thresh.(whish clearely isn't the case and further the time difference is huge)

and Brian as i think i've understood in ur posts u suggested Adapt Dmc of 3 and 6 with 0.005 but that still gave me the same noise i've had before.

guys i am very gratefull for ur answers i thank u and hope to hear more of u tommorow .goodnight and take care.

regards

[Brian Smith]

sorry Brian what i meant to say was for the 2nd and 3rd render which i understood from reading the posts u've made which i read so far.

guys could u explaine why Adaptive subdive and adap Dmc work differently.i mean logicaly to me if i can get pretty impressive results with ad Sub at 2 and 4 i should get the same with Dmc at 2 and 4 with the same Clr thresh.(whish clearely isn't the case and further the time difference is huge)

and Brian as i think i've understood in ur posts u suggested Adapt Dmc of 3 and 6 with 0.005 but that still gave me the same noise i've had before.

guys i am very gratefull for ur answers i thank u and hope to hear more of u tommorow .goodnight and take care.

regards

 

adapt subdiv 2 and 4 is completely different than adapt dmc at 2 and 4. here's a couple of screen shots from one of our books that might help

[fadi3d]

Hey guys thanks for still bearing with me

I did some tests as in the attachment and this is what I concluded.

1- Dear Brian I did those test after reviewing all I have of ur tutorials and a close reading of those pages from ur book think I can say I understand now that Ad sub an Ad Dmc behave differently and I used Ad Dmc Cause I read before u saying it should be used when there is a lot of Glossiness but not exceeding 75%.and as u can see from my tests the setting of 3-6 0.005 (Which seems to be ur preferred Setting or 0.001) still gave me some noise. Since my lc is high and my Ir also high what can u suggest? As Ad sub took 3 to 4 times longer to give me the perfect results I was looking for.

2- Should I increase my Materials Sub Multiplier (on the wood that has a lot of noise it is 25 on other materials I usually keep it to 8 or 10)?

3- Dear dave do u think my Vraysun/Physical Cam or light multiplier are wrong? : the multiplier in the cove is 30 (Vray Light Material ) as for the Ies they r left as is . VraySun/Physical Camera with Shuter 80 Iso 300.Sun Multip 0.5 Size mult 2.0

4- Should I rerender the scene with brute force or am I still Missing Something? Like perhaps playing with the Global Subdiv Multiplier?

And guys I really can’t thank u enough.