Normal Maps Format/Update (?)

[durp]

Hello,

after digging around and figuring out why the 'bump maps' (wrongly assumed it is a bump map) for the files like
AV8_B1.dds, AV8_B2.dds, .... AV8_B8.dds don't work as expected I had a closer look at them.

Those files appear to have a light direction baked in, which is not the case for bump maps, as their value change (dark to bright) is supposed to
change the (bump)-height.

 

 

this is from AV8_B2.dds, and the baked-in light directionality can be clearly seen.. so this excludes those are bump maps (assumption was based on the name, but it appeared weird those were used in the NORMAL_MAP slot in the lua file:
 

{"AV8B2",	NORMAL_MAP			,	"av8_b2", false};

 

With the presence of the alpha map I figured this could be something that was required in other flightsims to 'correct' the normal maps
by moving the red channel to alpha and usually leaving green and blue untouched.

Doing that I do get something that does resemble a (tangent) normal map where RED does relate to the light change in X and GREEN in the light change in Y (the Z change, however seems wrong imho)

(RED->X and GREEN->Y value changes present, so XY does seem to be baked into Green and Alpha)

The harrier textures contain some some 'normal' normal maps for parts like the pilot model and interior stuff, but the outside geometry solely uses those grayscale-non-heightmap-and-not-really-normal-map texutes.
Are those from a different engine still? (My reconstruction did not succeed, but I may missed a step) 

I do not believe that DCS does display those textures correct either, the alpha channel is not used for normals other than something related to damage (picked that up somewhere, so my explanation might be a bit... simplistic) 
The look does not change when removing the alpha, so this excludes that DCS might use something like other sims where the red->alpha channel copy was required.

 

walking a light  (direction top-bottom-top...) over the surface gives this:

 

The first part is a quick and dirty bump map I generated out of the panel-lines mask and converted it to normals
the second part is the original 'normal map'. (by normals I mean normal-map)

You can see the light transition in those dimples and groove has a weird looking specular direction change on the original texture,
which makes me believe that those are not working as intended.

 

Maybe I miss out something here, so I am open for feedback, the idea was to also implement adjusted normalmaps for liveries.

 

Edited July 27, 2023 by durp
null null null, pasting images still gives null-text...