splotches and hotspots

[Billabong]

I decide to make a hi-res render last night so I can really see my mistakes, but almost in every corner im getting either splotches or hotspots,I figured out how to get rid of the splotches, I was using QMC, I switched to Irradiance map and uped my Inter samples and that worked, but i still can't figure out how to get rid of these hot spots' can someone explain to me why. Here are my settings and a render

 

http://www.billa1.com/downloads/front_condo_hi-res.jpg

 

Image sampler: Adaptive QMC

 

Filter : VraylanczosFilter

Primary Bounce: Irradiance Map

Secondary bounce: Light cache

 

Adapative rQMC image sampler: 1/5

iradiance map

preset :high

Hsph Subd.: 50

Inter Samples 100

 

Light cache

Subdivs: 1000

sample size .066

scale: World

passes:4

Inter. samples :5

 

rQMC sampler

adaptive amount:.8

noise threshhold: .01

min.16

global Subdivs multiplier :2.0

 

Color mapping

type: Reinhard

sub-pixel mapping is checked

clamp output is checked

 

Vray sun

 

invisible

6.0

.35

.65

2.0

16

.017

4.167

 

Vray physical cam

f-number :12

shutter speed: 80

film speed: 150

 

All mats are vray mats, there are no standard max mats in this scene. I really appreciate any help.

 

-Brandon

[Mr-JosE]

Hi Brandon,

 

The problem you are facing here is the 'brightness' of your materials. The materials you're using are scattering the light at large intensities. You need to use a VrayColor map and turn down the RGB Intensity value to control this. This will also have the affect of reducing your render times.

 

José

[STRAT]

in the irradiance map settings, i would try.....

 

changing the Hsph Subd to 75, and the Inter Samples 40.

changing the LC scale to screen and using the default it sets you.

[Billabong]

I have never heard or read anything about materials being to bright and using the vray color map and man I did some searching. So I'm guessing this is becuase I'm using the vray sun and camera? thanks so much guys for helping me out.

[Ricardo Eloy]

When you use VRay's PhysCam and Sun, you have to make sure everything is physically correct, starting with system units. One thing you can do just to check is to remove the sun and cam and render it using standard methods.

[Billabong]

Thanks Rick, Maybe I should just go back to using target directs and reg. cameras

[Billabong]

Well I have added the vray color to my diffuse channel of this mat and turned it down to .8 and I am still getting this hot spot. I know this is coming from the vray sun shining directly to this point, so there has to be a way to make it more subtle, without turning down my intensity. Do I need to make the photon emit radius as big as the scene and then turn down my intensity. Thanks for any help guys

[Brian Smith]

i think you can remove those spots and improve your image drastically (especially the railings) by increasing the min subdivs on your qmc image sampling. i suggest 3.

 

a value of 1 just doesnt cut it in areas like your having problems with. for interiors with large smooth areas of evenly shaded surfaces, that value would be just fine...but not here. i doubt 2 would even suffice. also, the max value means nothing if your clr or noise thresh value is to high. the threshold value is the noise that vray tries to achieve, if you have enough max subdivs to allow for it. but if you set the thresh value too high, then it wont even make the higher subdivs that your max rate calls for.

 

very nice image btw

[Billabong]

Thank you so much Brian,

My clr threshold is set to .005, is that still to high, you don't have to answer that, I can do some test to figure that much out. Thanks so much again

[Brian Smith]

Thank you so much Brian,

My clr threshold is set to .005, is that still to high, you don't have to answer that, I can do some test to figure that much out. Thanks so much again

 

not at all. anything max rate above 6 (imho) is usually overkill and 6 is usually tied to values around 0.005 anyway. that is actually my default value. in other words, if you use 0.01, then having a max rate of 6 will do you no good because the threshold quality is so low that vray will probably only attempt to subdivide 4 or maybe 5 times to achieve that noise quality. on the flip side, if you drop the clr thresh to 0.0, this will do you absolutely no good if your max rate is set at 3 or 4, because no matter how perfect you specify the clr thresh to be, vray will never be able to achieve it with so few sudivs. in fact, the lower you drop the clr thresh, the less adaptive the image sampler is. that means that with a clr thresh value of 0.0, the min rate means absolutely nothing. in other words, with a clr thresh of 0.0, and a max rate of 6, you would get the exact same results (render times and quality) as you would by using a fixed sampler with a subdivs value of 6.

 

just remember to always disable the 'use noise thresh' option so that you can control image sampling noise separately from all other noise types.

[Billabong]

OK, I understand your point, I have raised my min/max, and keeping the clr threshold on .005, but I still get the splotches and the hotspot and the jaggedness, Am I going to have to raise my HSph Subdivs above 50. I know your probably going to say yes, but that dramatically kills my render time. Right now at the resolution I'm rendering at 2650x1600, it takes it a total of 15 hrs to render, Which I know isn't bad considering all the foliage and the res of the image, but to take it above 50 will probably double that. Is there any way I can avoid doing this. I am attaching my settings as well, hopefully it will help in determining what I am doing wrong. Thanks again for all your help so far

 

I mean to paste it in, but I am also using the VrayLanczosFilter

[Brian Smith]

OK, I understand your point, I have raised my min/max, and keeping the clr threshold on .005, but I still get the splotches and the hotspot and the jaggedness, Am I going to have to raise my HSph Subdivs above 50. I know your probably going to say yes, but that dramatically kills my render time. Right now at the resolution I'm rendering at 2650x1600, it takes it a total of 15 hrs to render, Which I know isn't bad considering all the foliage and the res of the image, but to take it above 50 will probably double that. Is there any way I can avoid doing this. I am attaching my settings as well, hopefully it will help in determining what I am doing wrong. Thanks again for all your help so far

 

I mean to paste it in, but I am also using the VrayLanczosFilter

 

no, i would definitely not argue to raise the hsph subdivs. i would argue to lower it (to 20 if possible). if you're getting splotches then believe it or not, i would expect that it's because of your noise thresh value (dont have time to explain), which i didnt know was at a ridiculously low 0.001. that value controls almost every area in vray (see manual) and using that value will bring vray to its knees. always leave at 0.01 at fix problems where they exist, instead of using a global fix like that (and global subdivs mult and min samples).

 

also you're adaptive amt should always be 1.0 unless using hdris (again, dont have time to explain why) and you can save a good amt of time not using a AA filter and still get a great image (its not the same as not using a filter with scanline)

 

that's all i have time for but you should definitely be rendering in a tenth of that time

[Billabong]

Brian I'm sorry but that didnt work either, still getting splotches, hotspot and jaggies, I'm wondering if switching over to brute force will do any difference

[Brian Smith]

there have been a lot of these posts that i've commented on. if you want more information you can search for threads that i've posted in that use the key words splotches and noise. that should pull up some good information that will help out.

 

btw, qmc will only help if your problem was gi related. to see your rendering in the best possible way, switch primary and secondary to light cache and use the progressive path tracing mode. turn off aa (this is a must), and dont worry about any other quality setting as they are all ignored. set the light cache subdivs to 65000 (the max), let it go for 10-20 mins and see what the image looks like. the blotches should definitely disappear but if they dont, then you have a problem that has nothing to do with any quality setting. it's then a scene setup problem. basically PPT creates a completed rendering immediately and improves on it. its like the maxwell render, but because it's so slow it's good only in a few situations...like this. in this case it can help isolate problems

[Billabong]

Brian I tried your suggestion and there were no splotches with the PPT method.

 

I think I have tried pretty much everything. I have tried my IM set to high, then back to custom and changed my min rate to -6, Ive taken my Hsph subs to 70, my image sampler on 3/6,.005, My adaptive amount is set on 1.0,noise thresh.001,Global subs 1.0, none of that worked, so then I tried Brute force , took it all the way up to 48, it came a lot closer to working,but was very noisy.

 

So then i thought, well maybe just a reboot is in order, so I rebooted and then merged everything into a new scene, that didn't work. I am really at a loss here.

[Billabong]

Ok, I don't think I have ever done as mush research as I have tonight. I am very close, but not there yet. I can see the finish, but damn if I can get to it. As you see the splotches are all but gone, but now if you look in the one corner where the arrow is pointing. I have got some kind of white burn marks goin on. Just in case you were wondering, what I think got rid of the brown splotches were taking the Interp. samples up to 100. I am posting my new settings in hopes that you guys can help me with the new problem.

 

If this ever gets fixed, it should be made a sticky(j/k)

 

Image sampler: Adaptive DMC

AA Filter: VrayLanczosFilter

Color Mapping: Reinhard

Multiplier: 1.0

Burn Value:.85

Gamma: 1.0

Sub-pixel mapping and Clamp output are both checked

Adaptive DMC image sampler:

3/6

Clr Thres: .005

Primary Bounce: Irradiance map

Current preset: High

Hsph subdivs: 42

Interp.samples: 100

 

Secondary Bounce: Light Cache

Subdivs:1500

Sample Size:.002

passes:4

 

DMC Sampler:

Adaptive amount: 1.0

Noise threshold: .01

Min.samples: 8

Global Subs: 1.0

 

I really appreciate all the help I've already been given and thanks again for continuing to help me.

[stephan-as-ice]

Sometimes it helps to switch a little bit the angle of the camera. But not in all cases. So give it a try....

[Derek Forreal]

Brandon, have you tried rendering with just an override material and glossy effects off? this could tell you whether or not its a material issue.

 

also, i appreciate that you solved some of the problem by raising your interp samples to 100, but i would agree with Brian when he says drop the interps (try 20?) and use default noise threshold (you currently have 0.001 = extremely low = longer that needed render times)

 

hth

[stephan-as-ice]

...and also don't use this RGB intensity very much. I've had problems with that especially on shiny surfaces. The more bounces are scattered through your scene, the more critical it would be to use this one. It's because they are pushing the whitepoint higher and higher each time! Like a car getting faster and faster before the wall stops it.