How to get better VRay renders (aka working in linear space)

[Gijs]

Just note that setting the bitmap input to 2.2 adversly effects HDRs/EXRs (if you plan on using them.)

if you load a hdr into Vray HDR loader, it is *not* affected by the bitmap input gamma.

[timmatron]

Shhh! At least make yourself look better for a few years - this way they dont fire you and you get better raises. Or give credit to me as I live around the corner from you so I can get a high-paying job there... (this had crossed my mind before simplifying the steps.) I don't want my 'competitors' in this city running me out of town...

Hey no worries! I already got them to switch over from Brazil to Vray so I already look good .

[Morbid Angel]

I took some time to follow the steps and see the differences in the renderings. My goal was not to match the colors or reflectance of objects, it was to see how the luminosity and color transmittance would work.



First image is richard's photo of cornell box. Second is unadjusted vray as we would normally get by default. Third is vray in gamma space 2.2 and finally maxwell.
We can see that in vray with gamma 2.2 the luminance is much nicer, and the colors seem to be more correct. However the new issue of extra noise have arised. I assume that by lifting the image so high the noise samples started to show. To get a clean render good for animation would take much more time as normal. I need to do more tests in that area, but this seems to be a great way for interrior stills etc.
Thanks to throb, gijis and juju.

[flipside]

Can't see your image.

Do you use gamma color mapping or do you use the 2.2 gamma output setting to convert the linear image into the 2.2?

[Morbid Angel]

sorry i had technical difficulties, try now. I used steps described in gijs's tutorial.

[Gijs]

Dmitry,

if you render to Vray framebuffer with gamma correction color mapping, the noise should disappear. In fact I am sure that your render is more noisy then normal, but also faster.

[Morbid Angel]

gijis its execlty as you have said, color mapping and vray frame buffer...

[Gijs]

hmm. pretty strange that you get a more noisy image in that case. Anyhow, I think there will be no much difference in render times with comparable noise level.

[timmatron]

But Morbid, what I don't understand is that your gamma corrected version has much less noise than the uncorrected version - except for the light at the top. What are the rendering times between the two versions? It would seem to me that the uncorrected rendering (linear) would need higher settings to get a clean rendering than your gamma corrected version.

[Morbid Angel]

well i thought of it and came to conclusion that you guys all use irmap for primary and i use qmc, because i cant use irmap, and that explains it all.

timmatron, the uncorrected version is with low sampling. gamma corrected version took 30 hours on a single node.

[timmatron]

well i thought of it and came to conclusion that you guys all use irmap for primary and i use qmc, because i cant use irmap, and that explains it all.

timmatron, the uncorrected version is with low sampling. gamma corrected version took 30 hours on a single node.

Woah, 30 hours. I'm sorry if you've explained this already, but why can't you use irmaps?

[Morbid Angel]

we do full on character animations and other complex animations with very setups which have moving objects which means irmap will have to be recalculated for every frame. This infact is longer and can produce worse results then of qmc. Things like sss surfaces that emmit gi onto another surfaces can be a big problem for irmap and lc, but qmc can turn it into noise and have it acceptable for render.

[timmatron]

Ahh now I see. Thanks.

[fewlo]

Hi all,

After studying this post (over and over!!) I believe I am now working in a Linear workspace and I am happy with my lighting levels, but after adding the colour correct plugin to my materials they appear very dark in the mat editor and do not really represent the final output in the VFB.

Am I doing something wrong or is this to be expected?

Thanks,

Fewlo

[flipside]

The color correct plugin is only needed when you want to convert old scenes to this linear workflow. If you made your materials from scratch, with the gamme 2.2 display ON, there is no need to put a color correct map in your color slots.