NIF file
NIF Files
NIF files are the meshes of TCS. Currently the options to edit NIF files are limited because no NIF exporter for the Oblivion format has been released by Bethesda. Hopefully they will soon.
The existing NIF files can be used in creating new objects in the TCS. They will have to be extracted from the BSA files first. See the Meshes and Textures category page for extracting details.
With the tool NifSkope you can do some rudimentary modifications on existing NIF files, like retexturing, adding transparency or emmissive color ("glowing" meshes). You can also remove polygon-blocks when the NIF consists of more than one, but you can't change the model's general shape.
Nif Import/Export Pugins For 3dsmax
3dsmax 6, 7 and 8 nif import and export plugins have been found Its buggy but will edit tes4: oblivion meshes (nif files).
But it does work i have tried it my self. I did not create this, I'm just leting people know, SO DON'T BUG ME! if it dosen't work but you can thank me for posting this and leting everyone know. I do however addvise you to check the site alot for updates.
so without further delay heres the link: http://niftools.sourceforge.net/wiki/index.php/NIF_File_Format_Library_and_Tools#3ds_Max
just click Download 3ds Max NIF Plug-in at the site.
Enjoy!
Cheers Wooby_6 e-mail me if you want: wooby_6@hotmail.com
(NOTE DON'T EDIT MY POST!!!)
Retexturing
Even though they can't be edited currently, they can be re-textured, see the NIF Retexturing page for details.
Exporter
The Main Discussion page has a post about using a Civ4 exporter thats partially compatible with the Oblivion NIF format.