Need explanation for Skyrim Facegen

[tomomi1922]

I understand character body mesh and texture pretty well for both Skyrim, SSE, and FO4. Been playing with Bodyslide and Unique Player Mod for the longest time.  I am currently playing Skyrim SE and am aware of the new _sk.dds for Sub-Surface Scattering effect.

I am still very lost for Facegen stuff.  I know there are head mesh and textures, that I presume takes care of the generic skin diffuse/normal/spec/sss.  And here are the questions:

- The head mesh (.nif) file will determine the head shape?  Per race?  

- What is tint mask and how does it fit into the system?

- Facegen is another mesh file (.nif) that determines exactly how a character looks?  Or is it stored in different formats?  (Why is it so hard to alter/copy a face?)

- When black face happens, beside missing one of the 4 texture files, what else would cause this?

It would be nice if someone can explain in plain English, or point me to a video tutorial that is easier to understand.  This bothers me for years that I am unable to have a clear understanding.  A lot of reading on the web makes my head spins than helps.  Thanks in advance.

[RomeoZero]

I don't have SE but can explain how Vanilla Creation Kit works in general for humanoids.Generally i think this game was made by Indian devs.To much mistakes.

About head mesh :

Spoiler

 

The body parts as fe-malebody\hands\feet\head are constructor for their races,each race have its unique assets for creating variable NPC facegen.

 Creation kit body parts are using its assets from this mesh folders "Female\Male" to create same generic body for all races.That's why there are no diversity in body shapes.Instead they made variable headparts with race morphing files (.tri data) to somehow distinguish Races,but they all using single head mesh source.

About tint mask :

Each Race use its detailed face normal maps (object space map _msn) for random face generator (if you use the same map for all races they will be just clones no matter the morphing data).All NPCs will look the same in faces.So they made facetint maps (detail maps~ age\scarring\roughness)  for facegen shaders (face tint ~ skin color\color lips\shades) to also compensate engine face randomizer, instead of dynamic normal mapping data pipeline, and they fucked up.
about body color shaders :

Spoiler

 

Face tint shader* -  in head mesh  is the source to use face detail map complexions on its face such as :  dirt \ age\etc with face tint color (FaceTint folder)

Face tint folder* -  source for chargen texture skin colors and face tint masks in them such as tattoos\lip color\eye shades\nose shade\etc. Comes with 2 files in tga and dds formats.Tga is prob for lod mapping data. If somehow you change the color tint in dds file and not apply the same in CK character skin color,you will get face color mismatch and black face bug.Bcs data is drawn by engine in CK esp plugin instead.That is why you need to export new facetint  data by ctrl + f4 every time you change body color of NPCs or thier tint masks.  

Skin Tint body shader* -  used to match color in the game chargen menu of skin color tab. 

 

***Shader flag 2 : SLSF2  soft lighting ~ is sub - surface shader map that also defines body shading for ENB SSS tab. 

_sk maps also can differ body color parts such as hands\feet\head\body if they are not the same color or have different data in clothes\armour\bodies.***

And they fucked it up again.

 

 Blankdetailmap.dds map is the source for neck and body color match,it also used for fe-maledetail map [age 40\etc]

If detail map pixel bits are compressed, they will get color mismatch and character neck from body can be either darker or lighter.

Texture color depth are known to be destroyed by compression and make wrong colors. 

FaceGen - So if game engine need to generate a random breton npc bandit it draws sources from default male head nif and breton texture assets with breton tint masks.Each Race have its 5- 6 slot presets of random generated NPC.