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Vray light speckles
show user profile  herfst1
I've been working on this problem all night and some of today and I'm stumped. Yes, it relates to my Italian restaurant but I felt this problem deserved it's own thread as others might have had this issue.

I made a VrayLight -> sphere, small radius, high multiplier, and it looked great (perfect reflections, shadows, etc). So I instanced it a bunch of times and now it doesn't work as it should. In fact all of my lights are giving off this weird speckled effect instead of proper illumination:

I read that incorrect GI might speckle light sources so I made the Global GI black, white, hdri mapped, low multiplier, high multiplier -> no effect on the speckles. Thing is, if I remove the glass/liquids, it sort of works fine (though there are still speckles in the scene probably from other light sources).

Is it something to do with my light settings? or rendering settings (indirect illumination has no effect eliminating speckles)? I'm thinking photons are probably to blame but I never played with them.
read 3814 times
8/8/2012 11:49:49 AM (last edit: 8/8/2012 11:51:12 AM)
show user profile  reeves1984
Sorry if I misread. But this is another good example of debug debug! If you are unsure of what is causing it.

- Disable GI is it still there?
- Disable Reflect/refractions is it still there?
- Disable lights, is it still there?
- etc.!




--
Simon Reeves


www.simonreeves.com - VFX Artist & Blog
twitter


www.analogstudio.co.uk <-- I work here

read 3800 times
8/8/2012 12:04:37 PM (last edit: 8/8/2012 12:04:37 PM)
show user profile  herfst1
That's pretty much what I've been doing since last night. I've also been importing lights / materials between scenes. Seems the standard omni works fine but I don't want to use it as I was unhappy with the projected shadows plus I think it's beneficial to learn how to use Vray lights properly.
read 3795 times
8/8/2012 12:14:49 PM (last edit: 8/8/2012 12:14:49 PM)
show user profile  reeves1984
Good stuff!!

--
Simon Reeves


www.simonreeves.com - VFX Artist & Blog
twitter


www.analogstudio.co.uk <-- I work here

read 3786 times
8/8/2012 12:44:14 PM (last edit: 8/8/2012 12:44:14 PM)
show user profile  zeefusion
What happens when you check sub-pixel mapping and clamp output in the colour mapping rollout?
read 3781 times
8/8/2012 1:40:59 PM (last edit: 8/8/2012 1:41:54 PM)
show user profile  herfst1
I checked sub-pixel mapping and clamped output and it just made everything much, much darker. So I x4 the multiplier and still roughly the same result for the refracted light onto the table.

Here's a render (I upped the mid-tones a lot so you could see exactly how it's displaying the light):



So I loaded a brand new scene. Made a dark, red box on a dark, grey plane; added a VrayLight -> fine. Put a sphere around the light and gave it a black diffuse, near white freznel reflection (value:201), refraction (value: 253), and 0.8 glossiness for both -> speckles are back.

I'm now confused as hell because I swear it was fine before.
read 3771 times
8/8/2012 3:18:25 PM (last edit: 8/8/2012 3:37:16 PM)
show user profile  3joez
up your vray and material settings
Photobucket

read 3758 times
8/8/2012 4:09:57 PM (last edit: 8/8/2012 4:09:57 PM)
show user profile  Bolteon
that will happen with lower than necessary sampling for high intensity light.


the usual fix is subpixel mapping or turning on the clamp to 5 or so. if doing the subpixel made your render darker; you're doing something wrong.

-Marko Mandaric



read 3748 times
8/8/2012 8:01:41 PM (last edit: 8/8/2012 8:01:41 PM)
show user profile  herfst1
Thanks Bolteon, I really appreciate your expert advice. I will do some tests and see how I go.
read 3735 times
8/8/2012 8:55:06 PM (last edit: 8/8/2012 8:55:06 PM)
show user profile  herfst1
Well the sub-pixel mapping and clamping sort of worked, it's given me the radial illumination which has hidden the red speckles quite well (though not eliminated them entirely).

I'm thinking, though, after around 24 hours of messing with this I should invest some time studying the vray manuals, it might be quicker in the long run.

read 3727 times
8/8/2012 10:11:54 PM (last edit: 8/8/2012 10:12:40 PM)
show user profile  Bolteon
is that a straight render? ie no post/ps work?


if so; seems like your pretty close. at this point your samples for GI need to be messed with.

my suggestion though would be to take your GI and switch it over to brute force (primary) and light cache (secondary) under the standard settings.

your image will get grainy but then pump up your adaptive qmc sampler to like 1/24 @ .005 and you'll have a nice clean and detailed image.



//edit

start using the vray frame buffer... and the sRGB button to start lighting your scene's; you'll be happier in the end you did.

save the images out as exr's and then "add" contrast in ps or nuke after the fact. aka color grading.

-Marko Mandaric



read 3719 times
8/8/2012 11:55:27 PM (last edit: 8/8/2012 11:56:45 PM)
show user profile  herfst1
Thanks again, Bolteon. In answer to your question, no PS adjustments were made to the last posting. I think (if I remember correctly) that I turned off indirect illumination on the dark pic that I had to adjust as I was getting pissed off with long render times. My bad.

I did a really small render (320x240) at your settings and it was going to take around 3 hours. So I downed the DMC (my version of Vray [2.20.03] doesn't have QMC) and tried again with an area render of just the candle at your settings again and here's the result (19 mins later):

I was pretty happy with this and, yes, the frame buffer with sRGB is a great tool.

I also read Donavella's advice to Rob@Dynamic and saw that if I want the sub-sampling to be better I should reduce the render region division from 64x64 but when I tried that my render times exploded. So I increased the Global subdivs multiplier to 1.5 and drop the noise threshold to 0.005 and, 40 mins later, it gave a result that I think is a bit better (i.e. a more uniform radial glow).

So I'm going to render out my scene properly and see how I go. I just hope it doesn't take forever.
read 3707 times
8/9/2012 1:54:29 PM (last edit: 8/9/2012 1:54:29 PM)
show user profile  Bolteon
good man, way to piece it out and get results.

-Marko Mandaric



read 3696 times
8/9/2012 8:46:57 PM (last edit: 8/9/2012 8:46:57 PM)
show user profile  S. Silard
Please tell me you use vRay Physical Camera . Cause the renders looks like you do not , or you just do not use it well . Do something with exposure , the renders are way too dark .

Congrats, you found my signature.

read 3688 times
8/10/2012 12:44:22 AM (last edit: 8/10/2012 12:44:22 AM)
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