A few questions on "PBR Practice" tutorial on Marmoset's website

dongyfeng

I'm learning the "PBR Practice" tutorial on Marmoset's website. (http://www.marmoset.co/toolbag/learn/pbr-practice)

I have a few questions:

1. Between linear and sRGB, which one should I use in Photoshop and Maya when I input the (HSV and/or RGB) value in those software?

2. "Alternatively, you can find known values from various 3rd party sources, like Quixel’s Megascans service".
Is the Quixel's Megascans available right now? I installed the Quixel Suite, but the Megascans button was grayed out. If not, is there other places I can find the physically accurate values for materials?

3. Workflow problem: about the normal map of the camera lens model in the tutorial, is it baked from high poly model or painted using NDO? (for example, those cavity lines around the camera lens)

AdvisableRobin

2. Not sure about the release date of Megascans, however some charts already exist to serve as guidelines for creating materials.

http://seblagarde.wordpress.com/2014/04/14/dontnod-physically-based-rendering-chart-for-unreal-engine-4/

Also check out this https://docs.google.com/document/d/1Fb9_KgCo0noxROKN4iT8ntTbx913e-t4Wc2nMRWPzNk/edit

jfitch

Hey man! Glad you're learning.

1. RGB

2. Megascans is not yet available, but look at the links robin posted

3. You'd have to ask EQ but I'm pretty sure it's baked from a high poly.

almighty_gir

hi Dongyfeng,

let me try to answer these as best i can for you:
1. photoshop works in sRGB space so unless you're applying any kind of curve math to your textures while authoring them, you'll be working in sRGB. this isn't necessarily a bad thing though, linear is what all the math in shaders uses but sRGB is what your monitor renders with, it also allows you more control over darker values.

2. nobody really knows when megascans will be available in quixel suite. however, the material presets that the suite comes with are all using megascan content.

you can find physically correct values to many materials online, a couple of things to bear in mind is that the most important value to look for is the reflectivity. albedo can almost be anything you like, weirdly enough. but reflectivity is very specific to each material.
eg: black, white, red, blue, magenta plastic all have wildly varying albedo values, but their reflectivity is likely to be the same across all of them.

3. EQ is a magician. he's on holiday at the moment but i'll point him here when he gets back.

dongyfeng

Thank jfitch, almighty_gir for the reply!

Since shaders use linear value, should I convert the textures (albedo/reflectivity/microsurface map) from sRGB space to linear space before putting them into any render system/game engine? I don't understand if I need to do gamma correction in the workflow.

almighty_gir

You shouldn't need to do that. most engines will either only take sRGB, or will have the option to take either.

In Marmoset Toolbag2 you can click "Options" under the texture input, and check/uncheck sRGB to tell Toolbag2 which your texture is using. In UE4, there is a similar checkbox in the texture properties, i'm not sure exactly where but it's there.

kodde

Your game engine/shader will probably handle the conversion from gamma -> linear -> and the back from linear -> gamma before displaying it on screen for you. You might be able to set this as well if you want to deviate from how the game engine handles it by default. For instance UE4 will handle this for you automatically so you don't have to worry about it.

grimsonfart

Megascans can't come soon enough!!

EarthQuake

3. Base shape is baked from highpoly mesh, small details like text are added in 2d.

Highpoly looked like this:

dongyfeng

Thanks everyone for the reply!
almighty_gir, I found the sRGB options in Toolbag 2. Thanks!
EarthQuake, thank you for sharing your workflow. I learnt a lot from your "PBR In Practice" tutorial!