WIP Interior - tips + blotches

[paulison]

Hi All,

For this current job I've been finding everything ihas run smooth and the latest Beta is working perfectly although I'm still having one problem in relation to blotches on the ceiling:



There is no standard materials in the scene etc so i know this isnt the cause.

I think the culprit may be my displacement rug or the vraylightmtl with a multiplier of 4.

Does anyone have any experience with how to clean this up? I've also noticed a fair bit of grain near all self illuminating objects

I noticed ticking "check sample visibility" has an impact on where the blotches appear. Also, increasing the Gi settings reduces blotches but the renders are already taking 4.5h hours each.

heres some settings:

IR map min/max: -4, -2
Hsubs: 70

adaptive amount: 0.5
noise threshold: 0.004
min samples: 12

IES lights have their value lowered from 8000 to 500 and vray sphere lights in centre of spaces are 500mm diameter with a multiplier of 5. This creates a fairly dark scene, so to get the outside and inside brighter the colormapping multiers are set to 6/6. Could this be the cause of grain and blotching? my lights are not actually bright enough?

[timmatron]

I've never tried color mapping as high as 6/6 so I don't know if that has any impact on the spots. The color mapping does look funny to me. You are trying to simulate sunlight but at the same time all the other lighting indicates night render. The lighting is too even.

Hsubs at 70 seem high. What are your interp. samples? Your easiest fix for the ceiling spots would probably be to increase that amount.

Are you using qmc or light cache for second bounce? If lightmap, increase the size of the filter to reduce the ceiling spots.

And do you have Max/Viz exposure control enabled? If you do, turn it off & you might see better results.

Finally, damn that's a huge TV!

[Gijs]

I would render it first with all materials set to light gray (220) and adjust your lights until you can render a satisfying illuminance with 1/1 for color mapping. You should use the colormapping values only to slightly adjust the image although I am quite sure that the colormapping can't be the cause of the artifacts.

The simulated sunlight does not seem bright enough to me. What color mapping are you using?

[paulison]

Hi guys and thanks for comments. Colormapping is HSV and after looking after several other peoples images I can see what you mean....the sunlight isnt bright enough so im going to crank this value up

my interp samples are on 25 because i read somewhere that if you make this value too high/low then you can get black blotches everywhere. I'll try it out on 40 and see how that goes (thanks i totally for got about tweaking this value)

MY problem is clients all like to see a bright scene, but the only way i can do this is to use vray sphere lights and ies downlights to brighten things up which kind of kills the realism. I can see now that i need to make the sunlights effect on the scene more prominant than the interior lighting because at the moment they are contributing about the same to the scene. The balance is damned hard to figure out!

ill redo the scene with colormapping multipliers around 1/1 and see how this works. I found this method a bit slower though for some reason (but maybee more accurate?)

[timmatron]

It IS really hard to balance daylight & artificial light. Keep working on it & keep us posted with what you come up with.

[Gijs]

Well, in general you can say that in a daylight situation where sunlight is entering the room, it should be possible to make a good lit photograph. The same should apply to a rendering.
You should however keep things simple when balancing the light in order to keep your test renderings fast. One way is, to add one light at a time. This will help you better see the contribution of each light. If you add all the lights at once, it will be very hard to tweak your scene, since you don't know the contribution of each light to the overall image appearance.