Author Topic: Megascans/Bridge Exporter Updates + Workflow  (Read 75086 times)

2016-09-15, 20:18:40
Reply #15

GabaCGStudio

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Those combined with AO + Albedo is taking care of the deep shadows.

can you show workflow of creating this maps? using shadermap or pixplants or something like this?

2016-09-21, 07:00:54
Reply #16

subpixelsk

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Hi dubcat

what is the correct workflow/values for reflection in 1.5 dailies and megascans? do we still need to use LUT for glossiness maps? and how about reflection color/level? should it stay at full white and default 1.0?

Thanks

2016-09-21, 17:36:21
Reply #17

dubcat

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can you show workflow of creating this maps?[/quote]
Who knows whats going on behind the secret walls of Quixel. There are a few papers online on how to extract roughness, height, normals from photos. No idea how they calculate the specular maps. Those are F0 values in linear.

what is the correct workflow/values for reflection in 1.5 dailies and megascans? do we still need to use LUT for glossiness maps? and how about reflection color/level? should it stay at full white and default 1.0?
- Download my latest Megascan exporter, send to 3ds Max.
- Open the specular map in Photoshop and apply my Specular to IOR LUT in 16bit mode.
- Load the new IOR map in 3dsMax with gamma 1.0.

If you want to do everything manually.
Leave Reflection Level at 1 and 255 RGB.
Plug and play the rest of the maps, no hacks needed :)
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2016-09-23, 21:33:49
Reply #18

Majeranek

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If you want to do everything manually.
Leave Reflection Level at 1 and 255 RGB.
Plug and play the rest of the maps, no hacks needed :)

Tell me if I'm thinking correctly. When building shader from scratch I need:
- correct diffuse map
- reflection leaved at level 1.0 255rgb
- IOR (gamma 1.0) and glossiness map

I assume that by IOR map corona engine "knows" what kind of reflection strengh is applied. How do you make a difference between metals and non-metals? And how to prepare correct IOR map?
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2016-09-23, 23:48:39
Reply #19

dubcat

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Quote
- correct diffuse map
- reflection leaved at level 1.0 255rgb
- IOR (gamma 1.0) and glossiness map
Correct :)

Quote
I assume that by IOR map corona engine "knows" what kind of reflection strengh is applied.
And how to prepare correct IOR map?
I don't know how they sample the IOR from materials. But I can show you how the LUT works, and how you can make your own IOR maps if you only know what IOR you want.

Specular to IOR

#1 Convert a specular map to 32bit in Photoshop and sample a value.
      In this case the value is 0.0370



#2 Open my secret little IOR spreadsheet and input the value you just sampled. This will tell you the IOR value. (Just ignore all the stuff on the right side of the spreadsheet, that's stuff I use to generate LUTs).



IOR map to IOR

When it comes to IOR maps. Corona does this (1 / IOR map).

#1 Lets say this is your IOR map



#2 Convert it to 32bit

1 / 0,66 = 1,51 IOR



This is what my IOR LUT is doing behind the scenes. But now you know how to do it yourself.

Quote
How do you make a difference between metals and non-metals
Megascans doesn't have metals yet. I will update the Corona Bridge exporter when they include metals.

Head over to my Substance Painter 2 thread for PBR metal.
« Last Edit: 2016-09-24, 00:12:57 by dubcat »
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2016-09-24, 00:17:30
Reply #20

Majeranek

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Thanks for the explanation! It's really helpful.

Based on what you wrote. When I want build a plastic shader with unified reflection I can still use [1.0 reflection 255 rgb and 1.4-1.6 IOR] or [1.0 reflection 255 rgb and CoronaColor map with Solid HDR color set to 0,02-0,06 in IOR map slo]" and both of those will be pretty much the same, right?

Is it still correct in 'PBR Mode' to use  Reflection Map 1.4-1.6 IOR for shaders which don't have unified reflection like concrete, wood, etc.? Or now we must switch to IOR map method? Or maybe I'm completely wrong and things like concrete, etc. have unified reflection?

That PBR is giving me sleepless nights...

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2016-09-24, 00:29:33
Reply #21

dubcat

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Quote
1.0 reflection 255 rgb and 1.4-1.6 IOR
yes

Quote
1.0 reflection 255 rgb and CoronaColor map with Solid HDR color set to 0,02-0,06 in IOR map slo]"
0.66 Solid HDR ;)

IOR = 1 / IOR Map
IOR Map = 1 / IOR

1 / 1.5 = 0.66
1 / 0.66 = 1.5

IOR map is the way to go since you don't clamp the fresnel value. Too bad we need to do math, would be simpler to just load a .hdr/.exr with 1.5 value. But you know, why should 3D stuff ever be simple.

edit:
I just want to add.

Glossiness should take care of most of the fresnel changes. If you have to make big changes to the IOR map, it mostly means that you are compiling different materials into one single material. Try to split the materials up and blend them. Like "Pure Material", "Dirt", "Water" etc.

IOR map shines when you have to fake depth, like grass materials. Glossiness can't do that.

Quote
PBR is giving me sleepless nights
PBR should make your life easier.
Leave IOR at 1.3-1.5.
Control everything with Glossiness.
If you have to fake depth, use IOR map. If not, just leave it alone. (In most cases)
Split materials instead of compiling them into one.
Keep it simple and nice :)
« Last Edit: 2016-09-24, 01:04:33 by dubcat »
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2016-09-24, 06:12:45
Reply #22

subpixelsk

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I am now confused a bit - specular maps converted to ior are used for ior slot but which one should be used in glossiness slot ? Inverted roughness ? Or something else ?

2016-09-24, 10:15:03
Reply #23

Majeranek

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Quote
PBR is giving me sleepless nights
PBR should make your life easier.
Leave IOR at 1.3-1.5.
Control everything with Glossiness.
If you have to fake depth, use IOR map. If not, just leave it alone. (In most cases)
Split materials instead of compiling them into one.
Keep it simple and nice :)

Now when you explained everything and I know how it works it should be easy. Thanks!
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2016-09-25, 20:28:48
Reply #24

dubcat

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But which one should be used in glossiness slot ? Inverted roughness ? Or something else ?
Yes, check invert in the output section of the roughness map :)
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2016-10-13, 17:23:18
Reply #25

dubcat

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New Corona Exporter update!
If there is a fuzz map available, the exporter will generate my Unreal 4 FuzzyShading port.
Core Darkness, Edge Brightness and Power are labeled, so people know what to adjust.

This is what you get

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2016-10-15, 20:25:24
Reply #26

SmurfN

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so what download settings for materials is the best to use? specular + gloss maps?

2016-10-15, 21:17:46
Reply #27

dubcat

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so what download settings for materials is the best to use? specular + gloss maps?

For Corona yes :)

I've been chatting with one of the developers. They will include my Specular to IOR LUT in one of the Bridge updates. We can use the new Corona LUT map to auto convert specular to IOR :D
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2016-10-17, 17:25:18
Reply #28

ktulu

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Hey Dubcat,
first, thanks a million for developing this script - it works like a charm and is a real time saver!

I was just wondering, why doesn't the script load bitmaps as CoronaBitmaps but regular max ones? Is there any reason why you chose not to do it?
I know I could run DeadClowns script and batch convert them after the import process, but this is one step I would like to do without if possible.

Cheers

2016-10-18, 09:09:12
Reply #29

dubcat

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I tried CoronaBitmap when it was new, but I saw no reason to use it over Bitmap.
Did a test now to see if there was anything new, CoronaBitmap still give me 5-15% slower render time.

But if you guys really want CoronaBitmap, I can make the change.
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