Octane Basic PBR Setup Tweet

[tcheng00]

Hey Guys,

I made a video on using the Slate Editor to setup a PBR texture set with Universal Materials. Good for those who are starting out. Enjoy.

https://youtu.be/Op_JUQUa1_g

-tom

[maneality]

Looking good. Is there any way to figure out if we need to invert the normal map G channel at all or is it trial and error to see what looks good?

[tcheng00]

Looking good. Is there any way to figure out if we need to invert the normal map G channel at all or is it trial and error to see what looks good?

There's no easy way to figure it out without trying it. You can only ask the author how it was done. Otherwise, trial and error unfortunately.

[samsue]

Hallo,

About the Normal Map, paride commented in another topic that as a general rule the normal map should always be 2.2, which makes sense.

"Note: When you use a bitmap for bump or displacement mapping (including normal mapping), 3ds Max considers only the numerical value of the pixels, so gamma correction is not needed. When you load such bitmaps, we recommend you choose Override and set the gamma value to 1.0 (no correction). This can be especially important if the values are computed exactly, as for normal bump maps, height maps, and so on."

Fonte
https://help.autodesk.com/view/3DSMAX/2 ... F5172219B5

.....

maybe I'm wrong, but thinking now, if you use gamma 2.2 on the octane rgb map, leads to wrong values.

viewtopic.php?f=27&t=74322&start=10

[tcheng00]

It will depend on the application. It is true that if you use 3ds max bake to texture, the normals are baked out of max with a 2.2 gamma. I already spoke to the max development team about introducing a proper gamma output control. They are looking into implementing it. So we are both correct

Btw, you can overcome this max gamma problem by baking out to .exr and resaving from .exr to another format.

[samsue]

Hey,

yea, about the "proper gamma output control" would be good not only on maps, but in general, gamma in Octane is a bit tricky. " gamma hack, response, gamma, order... "

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But I don't think that theoretically that example below is right, because even though it looks okay, max is seeing a lot darker this map than he should be.

[tcheng00]

Gamma is a complicated topic that was created to compensate for CRT Tvs that had a weird logarithmic curve when displaying color. Basically, CRT was displaying the source material too dark. So they compensated for this technical problem by adding a 2.2 gamma hack to the source material. These days, LCD tv do not have that problem due to compensation with LUTs, but due to legacy workflow from the old days, we still apply a 2.2 (or similar) gamma to the color output for our display. If we are not displaying the texture on screen as color information directly, a linear color space should be applied to all data texture maps, which should also include Normals. However, it is a complicated topic and can be very confusing to decide what is 1.0 and what is 2.2 gamma. So I think Autodesk just kept it simple by making everything 2.2 gamma when you bake out of Max. In a way, this makes sense if you work in Photoshop, it treats everything with a 2.2 gamma, unless you use .EXR. This is technically not correct way to work, unless you also account for the file format. .jpg and .png usually carries a 2.2 gamma (not a hard definition), but .exr carries a 1.0 gamma (this is inherent in EXR design). That is why I contacted them to add a gamma output control. Anyway, as you can see, you can get confusing texture gamma, and you will need to see which gamma curve works for you. If it was up to me, I would make everything standard to 1.0 gamma curve, but you will need to fight the entire industry(software, tv manufacturers, recording equipment, broadcast standards, etc.) to change that.

Typical gamma settings are:

1) 1.0 (linear - no gamma curve)
2) 2.2 (gamma curve)

Also, if you want to use imager, I would leave "gamma hack" on and set the Viewport to HDR instead of LDR, if you want to save out the texture beyond 8 bit range from the OctaneRender Viewport.

[samsue]

I didn't want to cover it that much, but that's exactly what you said.

That's why when dealing with linear working environments (3DS MAX, Nuker ... ), all textures that deal only with information (normal maps, rough, bump ...) when we're working with jpge that comes standard applied gamma 2.2, with exception, from Albedo, all maps in Octane's RGB Map should be set to gamma 1.

I've been confused again

1. 3DS Max apply a invert gamma curve too all loaded images
2. Octane Gamma 1.0 applyes 2.2 (gamma curve) so all look bright but this only in the view, but the image is "lienar"
3. For the albedo, i dont get anymore how should work

[tcheng00]

I didn't want to cover it that much, but that's exactly what you said.

That's why when dealing with linear working environments (3DS MAX, Nuker ... ), all textures that deal only with information (normal maps, rough, bump ...) when we're working with jpge that comes standard applied gamma 2.2, with exception, from Albedo, all maps in Octane's RGB Map should be set to gamma 1.

I've been confused again

1. 3DS Max apply a invert gamma curve too all loaded images
2. Octane Gamma 1.0 applyes 2.2 (gamma curve) so all look bright but this only in the view, but the image is "lienar"
3. For the albedo, i dont get anymore how should work

To keep it simple, think like this -

Color texture should have a 2.2 gamma curved applied
Data texture should be left alone at 1.0 gamma (no gamma modification)

Leave Max display gamma default alone, leave Octane display gamma default alone.

If you want more info - Here's an article related to Gamma and Display Gamma
https://www.cambridgeincolour.com/tutor ... ection.htm

[samsue]

many Thanks tcheng00

I ask because I want to understand the subject in depth