Grainy renders in Vray

[xtremist999]

Hi there,

Hi there,

I've lit an interior scene up with predominately V-Ray lights and I've turn on GI. My settings are, Min rate: -4, Max rate: -1 and HSph. subdivs: 30. The rest are default settings.

I'm still fairly new to V-Ray and I'm wondering why my render looks so grainy? What kind of settings can I change to reduce the grain?

See the attached image
http://www.geocities.com/xtremist999/006a.jpg


Thanks!

[Antievo-3DT]

Quick Reply:
This is a sample/subdiv problem in the renderer or in the material you are using. My guess would be that the samples in your VRay material and/or VRay light are not high enough. Can you please post more spesific material, render and lighting settings? That would help determine the problem.

Best Wishes,
Antievo.

[Kage]

Because its an enclosed space, there simply doesn't seem to be enough photons bouncing around.
Plus, those are vey low settings for renders. There okay for test renders at high res's, but if its a very small render, that low won't do it any good at all.

[Antievo-3DT]

Quick Reply:
Aha! My bad! I should have gotten' that...
I apologize for the unclear/fauly advice
Thanks for correcting me, and nailing it Kage.

[xtremist999]

Thanks for the quick responses guys.
I've always just used those settings because they rendered images fast, but this was the first time I've used it in an interior space. That render was just using default grey Vray material by the way.

So what settings do I have to change to raise photons? or are there any settings I could change to smooth out the current grainy photons?

Sorry if this seems really obvious, its cuz I don't understand all of Vray's terminology.

Thanks!

[Kage]

Try making the min samples 1 and the max samples 2, or if that takes too long, min samples 0, max 1, or min samples 1, max 1.

Also, turn up intensity on the lights, and put up the Moni-Carlo bounces.

Also, if you have a Vray light, set samples in the modifiy panel to more than 8 if thats what its on now. 12 is okay, and is alot less patchy on shadows (since they'll be alot in a room)

[brentagain]

yeah usually for test renders use the light map option rather than irradiance map.It`s a lot faster.
If your new to vray then using irradiance map for your final image just use one of the presets built in.A high preset will give you 4 passes a low will give you 2 passes and so on.
I high preset usually gives good results.

[tecsun]

I would suggest to use the irradiance + light cache to have a better result + render time during testing. QMC consumes quite a lot of time and give lots of noise. For the irradiance settings, I use min = -5, max = -2, it gives a nice result without any noise, so I think there is no need to increase the max rate value to positive since it will kill you with the long long render time.

Good luck~

[Kage]

-5, -2?... What resoloution do you render at? Using an irradience map and Quanti-Carlo with this sort of setting just looks awful...

Whats other advantages of using Light Cache?

[tecsun]

I used to render at 2500px resolution (the largest I done is at 5000px) and the -5, -2 doesn't give me any problem. In vray 1.47 it may needs to raise the max to -1 or 0 to get render detail area, but with 1.5 0 details enhancement, max=-2 (sometimes I even drop it to -3) already can handle quite well.

emm.. light cache is vey fast compare to qmc, I tested with a same scene, irradiance+light cache is sometimes 2x or more faster than irrad+qmc. I know qmc does give a lot of details and produce nicer result (sometimes), but in my case, irrad+lightcache bestsuite esp on tight deadline.

for light cache setting.... I sometimes used 300 only (if I forget it at all when final render at 2500), but in lot of my interior render, the result is not very obvious between low and high value of lightcache. I still can't figure out why, but Vlado recommended to use 1000 above though (if I didn't misunderstand the article I read) :P

[xtremist999]

thx guys, i'll try out the differents settings