SSE Architecture normal map problem, turns diffuse dark

[Nap1985]

https://www.flickr.com/photos/196879697@N03/52707819343/in/photostream/

https://www.flickr.com/photos/196879697@N03/52706810777/in/photostream/

 

I'm really just messing around, but I'd like to work on making my own city texture replacers. I'm pretty newb, have only done textures and normal maps for player/npc skins, and the process I used then isn't working correctly for architecture. You can see in the pictures I linked above, when I apply the normal map I made, it turns the diffuse texture really dark for some reason, and the normal map is completely flat when applied to the mesh, but looks correct when opened in Gimp. Anyone have any ideas?

[maxarturo]

Your normal map doesn't have an 'Alpha Channel', so the mesh hasn't any light reflectivity for the normal map's high and low values to work in-game.

[Nap1985]

Thank you, that's interesting. I had considered that and they DO have an alpha channel. Though what it's doing I'm not certain, and not certain how to make it functional, but for example when I open in Gimp it says "RGB Alpha" and if I click the "Transparency" selection it has the option to remove alpha channel. I just tried "Color to alpha" and made everything white transparent, and this sort of worked. The normal map now has texture (Highs/lows) and is no longer dark, however, now it's absurdly reflective like it's made of polished metal or something. But this is progress...I think!

 

Edit: Ok, when using the normal map plugin in Gimp, if I change the Alpha Channel selection to height or inverse height, it seems to work. Mostly. But still makes it super reflective. I've been opening other maps (made by other modders) just to see how they look in gimp, and they look like the ones I was making (without changing alpha selection to height), and yet they work. They don't have visible transparency anywhere in the image, all blue/red/green, and yet the only way mine function is with visible transparent areas (checkered background in gimp). Am I making sense?

 

I've made normal maps before for tattoos in Fallout 4 and they worked fine without having these issues. Which is why I don't understand what's so different for architecture.

Edited February 24, 2023 by Nap1985

[scorrp10]

Highly recommended:

https://wiki.beyondskyrim.org/wiki/Arcane_University:NIF_Data_Format

 

Alpha of the normal is specular. Black means completely non-reflective, white is shiny-glossy.

Here is an example of textures\architecture\riftenplazabrick01

Left is diffuse, middle is its normal's RGB, right is normal's alpha.

 

 

As you can see, mortar lines on the alpha are black, brick faces are varying shades of gray.

Taking a desaturate of the diffuse and pasting it into alpha is usually a good start, but you usually also want to give it an S-curve.

In Blender, you can observe the effect by taking the texture's alpha output into BSDF specular input.

[Nap1985]

That's very helpful, thank you! I was making the mistake of desaturating and then cranking up brightness and contrast for very bright whites and deep blacks. Still having issues with reflectivity, but better.

 

I suppose I'm missing a step? I have been simply desaturating the diffuse and creating the normal map from that, which is what the guides/videos I've found recommended.

[scorrp10]

That only works to a point, and only where recessed = dark and raised = light. Consider generating a normal map for a wooden chess board. Or dark stitching on light leather.

Take a look at this article as well:

https://katsbits.com/tutorials/textures/how-not-to-make-normal-maps-from-photos-or-images.php