nDO2 normal map Red channel Confuuusion!

MrOneTwo

My problem is that when I crate normal from selection via nDo2 it gives me result with flipped red channel. Sometimes its really hard to interpret normal map but I hope you will be able to know what I mean:



So here is normal. Only part I created with nDo is this indent.This is normal map with CORRECTED NORMAL MAP! With the arrows I try to show how I see normal map. Since those colours (right side; those were baked in max) represent downward slope from left to right (like in drawings in boxes ;p) I figure they should be same in this indent. Here I already switched red channel so they look ok. But right from nDo2 those vertical lines of the indent are switched. Why does it work like that ? Arrow 1 shows green channel which is fine. Arrow number 2 shows red channel.

Using 3ds max 2012 with nitrous.

Joshua Stubbles

You can set the normal creation options in NDo and specify what channels are flipped if any. If it still remains a problem, you can always invert the base normals to match, then when the output is final, invert as needed.

MrOneTwo

Thx for replying. How come it even happens ? It seems like something that can't go wrong. Especially that no one else had problems like that here (not that I know).

odium

Hmmm... Call me crazy, but to my eyes, that "indent" is actually sticking up, i.e. not an indent? Now granted everybody has slightly different green channels and directions and all that jazz, but I was under the impression we were all slowly moving away from all that and going with a standard?

Makes no difference like, as its all down to the program that renders the normal map anyway

MrOneTwo

It looks like its sticking up but its illusion since it depends on colours. Thats why I made those arrows and drawings ;p At least thats how I understand normal maps. I think the illusion works because our eyes are used to top lighting. Since upper border is light green/blue and lower is purple the difference in lightness forces our brains to think its sticking up. But When you look at the right side of normal map its other way around. Since right side is baked in max and it looks ok in viewport I suppose its like it should and thats my 'formula'. At least thats how I see this topic. Feel free to prove me wrong

Ace-Angel

What standards? Some games still keep the Red channel or Green channel in the Alpha slot for better compression, I would hardly call that a standard.

odium

Standard as in, back when normals started, it was hit/miss what way up the channel was going to be, but these days you find more and more games using X+ Y- Z+, rather than the other way around. In fact I can't think of a game right now that uses the other way?

I'm not saying its a standard, or that it even matters at all, because as long as the engine displays it the same, who cares, right? But when working with so many different assets in so many different engines with so many different programs, you get used to a certain way. For exampple, any id tech game, UE3, any Bethesda game like Skyrim, the COD games etc, they all use X+ Y- Z+. So its odd to see it the other way around, because your eye trains to seeing the normals as a 3d effect.

Farfarer

That doesn't look broken to me.

More red = surface points more to the right of the texture.
More green = surface points more to the bottom of the texture.

Both of those surfaces (the leftmost edge of your indent and the leftmost edge of your baked detail) are supposed to be pointing towards the right hand side of the image as they're both the sides of indents. therefore are both strongly red.

MrOneTwo

Like I said this pic shows normal AFTER FIXING! I knew it will cause troubles but I made that pic and then trashed what I was doing. Was easier to post fixed and write "ITS FIXED ONE!". Sorry for that.