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Format for normal maps... why are they showing gray?


misterbk

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Hi guys, hopefully this is a simple question...

 

I'm used to normal maps being RGB images representing normals as components of tangent-space on the model, i.e. R='U' , G='V', B='Geometry Normal'.

 

But when I open up normal maps from texture packs I've downloaded from the Nexus in Photoshop using the DDS plugin, they are grayscale, i.e. the R,G,B (and A) values are the same. (Natural Bodies is what I've opened so far.) It looks more like a 'bump' map.

 

Stranger still, it looks like parts of the maps were at one point RGB = UVN (tangent space normal maps) but someone took the R channel and copied it to G and B to make a grayscale image out of the U component of the normals, i.e. surface details that would face to the left are brighter and surface details that would face to the right are darker.

 

So, which of these is most likely going on...

 

1: Does Dragon Age use a different normal map format than what I've been (successfully) using in Fallout3 and New Vegas?

2: Is my import / export busted somehow, i.e. am I not seeing the same thing you are seeing if you open e.g. HF_100_n.dds?

3: or, did the mods "cheat" and use a grayscale image because they could pull it from the color map, because it saves work and does give some bumpiness effect in game?

 

 

I'm opening the normal maps on Windows 7 x64, and they appear the same through each of these viewing methods:

 

* Photoshop CS4 32-bit, using the 32-bit DDS plugin (that has previously worked and I got correct results in Fallout)

* Photoshop CS4 64-bit, using the 64-bit DDS plugin (which is a bit newer, just got it, and haven't tested it, but it opens my other normal maps fine.)

* The DDS thumbnail viewer plugin for Explorer. (The normal maps show grayscale through it as well.)

 

 

Also I searched around for a bit but I figured a search for "normal map" would get me something if it existed... But only five topics showed, none of them helped.

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Hrrmmmm... Maybe I posted too soon. Browsing around through some posts led to a wiki that explains the normals use grayscale RGB for the U coordinate and Alpha for the V coordinate and then calculate N on the fly, which is still a bit odd since the textures I've opened all had 100% identical R,G,B and A channels.

 

Because of that I'm still not 100% sure my tools are working correctly for opening DA normal maps. Do other people see an alpha channel that is different from the R,G,and B channels?

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OK, I think I've figured it out.

 

In creating the "Grainy HD" normal map being used for the Wet Skin variant I installed with Natural Bodies, looks like the author blew away the info that was in the Alpha channel of that normal map, leaving the R,G,B and A values the same. When I opened up some of the original Natural Bodies normal maps (from the core files) they did have an Alpha channel with different color information than the RGB.

 

So, never mind, I figured it out.

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