Brute force Test Very slow :(

[^Lele^]

Thanks so much Lele. Glad I found this thread and hence the 31-page giant thread about this low albedo approach.

Argh, i hope you didn't read all of it!

[jasonhuang1115]

Argh, i hope you didn't read all of it!

haha....not word by word, but I got the gist of it after flipping through all the pages. And it all makes sense when I re-read your posts of this thread.

[Ihno]

It's entirely my fault.
I spent a wee bit of time with hundreds of VRScans, profiling their measured response in RGB in a way which returned the exact albedo value (as Normal fraction, or 0.0-1.0, or %, as you wish to read it) at each incidence angle (more precisely, i sampled it at 10 bit, or 1024 samples across the 90 degree angles), and then we all got lost into other stuff, and I personally never came around to preparing the post.

Too bad, will you come back to this by any chance? I think it would be incredibly useful for getting a feeling of how real world albedos are.

[piotrus3333]

that would definitely be interesting.

[Crayox13]

Guys...how would that translate in vray setups? I mean I often had problems with noise popping up where it shouldn't because I often had scenes with dark materials that I needed to be even darker. Also they had lights with mult 1.0 so my scenes had cameras with shutter speed and f number of like 2, and 4. In the end you get the same result but I guess those low light settings messed up some thresholds so vray couldn't clear the noise even on high settings. I know that progressive render cleared certain areas of my scenes but the problematic areas just continued to have a lot of weird noise. I sent the scene to chaos but they too said they don't know what to do really.
So my question is what multipliers for sun/sky do you use? If vray sky is in light dome texture.

[piotrus3333]

VRaySun on 1 or 0.04-0.05 if cameras are without exposure.
how dark are your darkest materials? (rgb of color swatch in max or lowest rgb of textures)

[Crayox13]

Sometimes I get to 1/1/1 - 3/3/3 in rgb, then I usually just use color correction to make them even darker, since around these values I also loose any color, it's either 0 or 255 in saturation.
With sun 1.0 do you guys use values of 10-30 for dome light with vraysky?

[piotrus3333]

way too low albedos. unrealistic input will give you unrealistic results. start with good input and everything will fall in place by itself.

[Crayox13]

What is a good input?

[piotrus3333]

start here (terrestial albedo section):
https://en.m.wikipedia.org/wiki/Albedo

you can find tables for more materials online.

[Crayox13]

But that's for developers. As I'm sure you understood, I meant how does that translate in terms of default settings. By now vray has come out of its developing stage. I know that many scenes need special tweaks, but there should be a guide, as you get with every tool you buy , how to start. What are the main light intensities one should use to get a daylight scene? Or...if should we keep the camera in shutter speed range of about 100, f number 8 and then adjust our lights to match this? Should we still use rgb values of about 128 for our whites or is it ok to use say 220 now?

I've came across few bugs if you use low camera values...also low light mult values.

I often read vray docs and they are helpful but sometimes they miss these basic settings - how to start. (unless I missed something?)

I know we were in an era of discovery and development but now I feel we are out of that and we should start using the research results that came out of it.

[piotrus3333]

But that's for developers.

it is for users. so they feed the engine with proper data. you put in numbers and vray spits out pixels. it is setup by default to simulate real life light. so is vray sun and camera - defaults represent sunny day.
so it should be logical that you should follow real life while creating shaders. your dark ones reflect 10 times less photons that darkest material on this planet (more or less). vray will see them as almost black holes sucking in light.

[Rens]

Keep in mind that albedo means the total of light reflecting back, so that includes diffuse part + reflecton + specular, not just diffuse. That could make a couple of % difference.

[piotrus3333]

but that is handled automatically in VRayMtl.

[Rens]

True, diff gets multiplied by the reflection filter.