[Texturing] N-suffixed textures

[Aiwyn the Breton]

...I can hear someone say "Oh crap, not another one!"
Yess, guys, Aiwyn is here with a brand new tecnical question for you!

In Oblivion's data, there are several n-suffixed textures with the same name of normal textures (as rope.dds and rope_n.dds). These textures looks as bump/displacement maps to me (as I have seen loads of bump maps in my modeling experience) or perhaps light related maps (I have seen a few of them, but I'm quite new on using them, mostly in poser/Daz Studio), but I didn't see any reference to them in the nif models, nor as bump maps nor as other kind of additional/effect maps. So, what are they? How they are used? I have to set up something in the NIF for using them as far as you know?
Plus I wonder about the "_n" thing... underscores "seems to confuse the engine" (I quote Lady Nerevar on a previous topic), so why they have the underscore in the name? Or it's because this kind of maps have an undercored filename the engine gets "confused" when you use it on a normal mesh/texture filename?

Or, last minute thought, are they alternate map for the nighteye vision? If they were bumps the should have been named as "_b" not "_n"...

Anyone knows?

[aro101]

They are "bump" maps, it is only that they are called "normal maps"... That's from where the n is from. The _n is also used by the game engine, because it automatically looks up for every texture if it has an _n equivalent. You can get more info here: http://cs.elderscrolls.com/constwiki/index.php/Normal_Maps

[Aiwyn the Breton]

so the engine automatically recognizes them automatically?

[aro101]

Yes. That's why there is no reference in the nif files. It is not needed. There is a simillar situation with nif files with _far added at the end of the filename.

[Aiwyn the Breton]

Thank you. So if I ever make a custom tx I'll have to make the _n as well.

[aro101]

No, but it is highly recommended. The game works fine without normal maps.

[Lady Nerevar]

actually, i think that normal maps make clothing appear transparent (either its that or some other error i make frequently when retexing).

anyways, there are several suffixes that correspond to maps that are automatically recognized by the engine. you need to know _n and _g, and maybe _far. _n is the normal map, which is a bump map plus an optional alpha chanel for reflections. _g is the glow map, used for things like gems that need to be uber reflective and glow in the dark. _far is for models and contains a low polygon equivalent of the main model to be used if the model is marked Visible when Distant.

having underscores that dont correspond to other maps sometimes causes the engine to not render the textures correctly. we had a problem with the goldmoor rocks for example where they would not respond to light because their texture contained an extra underscore. underscore textures are useful however if you want to do recolors that use the same normal map (thereby saving space). say you want a blue flag and a red flag, you could have flag_red.dds, flag_blue.dds and flag_n.dds, where the normal map would be the same for both flags. or at least in theory, havent tried this myself yet

[Gez]

They're suffixed _n because they're normal maps. What you call a "normal texture" is not about [url=http://en.wikipedia.org/wiki/Surface_normal]normals[/url] at all (and this betrays ignorance of the jargon), it's a [url=http://en.wikipedia.org/wiki/Texture_mapping]texture map[/url]. Then there are also glow maps, parallax maps, and many others. Height mapping for example, is a type of displacement mapping. Transparency can be handled by an alpha mapping.

In short, texture is just one type of mapping that can go on a model.

[Aiwyn the Breton]

What you call a "normal texture" is not about normals at all (and this betrays ignorance of the jargon), it's a texture map. Then there are also glow maps, parallax maps, and many others. Height mapping for example, is a type of displacement mapping. Transparency can be handled by an alpha mapping.

I knew that, Gez. It happens sometimes, that foreigner modeling slang - specially in italian architecture college - it's slight different from strict tecnical jargon, and sometimes I use that slang (or something equivalent) instead of the right terms. I apologize for that, I should have learned not to post in a non-mother language after 11pm without having drink a Vodka Red Bull. Anyway, I think missing two quotation marks around the word "normal" betrays lazyness in posting. Mea Culpa.
Thanks, anyway, I got it.

[aro101]

actually, i think that normal maps make clothing appear transparent (either its that or some other error i make frequently when retexing).

If your clothing appears transparent, take the normal map of it and remove (RGBA -> RGB) the alpha channel from it.


AMEN

[Lady Nerevar]

nah, thats the point, it doesnt have a normal map when it disappears. when i get one it appears again. anyways, its not a problem, i got it sorted out

[aro101]

omg, shit, wierdstuff.

[Aiwyn the Breton]

uhm, that's weird. In which kind of objects happens this? Only on clothes?

[Lady Nerevar]

ive only had it happen on clothes. its not really something to worry about, but if something doesnt appear or work right the normal map is something to check out.

[NexUmMonastica]

A "NORMAL MAP" is not a bump map.
NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO

It is a texture filter which depicts the way light reflects off of an object. Bump maps have no light characteristics: and are usualy coupled with "specular" maps. Normal maps don't 'bump' the texture at all, but as a light moves past the object the texture will react as if it was a "displaced" map (or simply put: 3D) Its how the walls in the starting dungeon in OB look so real: If the texture is illuminated within the mapping tree it looks plain, but if you shine a light upon it it will appear 3d.

hope that helps.