DDS Files
DDS is the file extension used to denote the Microsoft DirectDraw Surface (.dds) texture file format.
Oblivion employs the DDS format for textures. The Microsoft DirectDraw Surface (.dds) file format stores textures and cubic environment maps, with or without mipmaps. It was introduced with DirectX 7.0.
Although the format is not natively supported by most graphic editing applications, there are a number of Tools designed to handle the format.
DDS Settings used by Oblivion
| Usage | Save Format | Mip Maps | Image Type | Use of Alpha Channel |
|---|---|---|---|---|
| Textures without Transparency
(Most Models and all Landscape) |
DXT1,
RGB |
Yes | Color map | Alpha channel not available |
| Textures with optional Transparency
(Needs to be activated in NIF-File) |
DXT3, DXT5
ARGB |
Yes | Color map | Transparency
(Black = Invisible, |
| Textures with Parallax displacement mapping
(must be activated in NIF file) |
DXT3, DXT5
ARGB |
Yes | Color map | Displacement mapping
(Black = recessed, |
| Normal Maps
(*_n.dds) |
DXT3, DXT5
ARGB |
Yes | Tangent Space | Specular shine
(Black = no shine, White = high shine) |
| Glow Maps
(*_g.dds) |
DXT1
RGB |
Yes | Color map | - |
| Icons
(And other GUI elements) |
DXT3
ARGB |
No | Color map | Transparency in GUI
(e.g. Weapon Icons) |
| BookArt | DXT3
ARGB |
No | Color map | Transparency on Page
(Show Book's Background Texture) |
| Loading Screens | DXT5
RGB |
No | Color map | - |
NOTES: Saving a Normal map as DXT1 does not eliminate the alpha map per se, but simply packs it as a highly compressible all-white channel. This has the unwanted side effect of causing full specular highlighting over the whole mesh to which the texture is assigned to. DXT3 or DXT5 are strongly recommended for normal maps.
DXT5 can also function as a normal map format. DXT3 uses an Explicit alpha map, which has a noticeable step in the grayscale gradients of the map. DXT5 uses an Interpolated alpha map, which does not have this step and may be better suited for some situations.
Though parallax and transparency mapping can function at the same time, the formats in which the alpha channel must be configured for the two effects is usually incompatible and may produce unwanted effects.
Oblivion can also use uncompressed texture files, specifically 8.8.8.8 Unsigned format. This completely eliminates compression artifacts not pre-existing, but is significantly larger in file size (and thus harder on the video RAM resources).