ok I figured it out ;) Thanks everyone for the clues you gave ! For those who will have the same problem : As you can see when you click on "edit uv" on nifskope, the uv map is messed up. So before editing your nif files, Import your .obj files in outfit studio (oldrim version) and save them as .nif (uv map is now correct) Open your new .nif in Nifskope (1.2 is ok for me ) and export the NitriShape to a new .obj (with good uv map !) Then do your textures in any software At the end, you will have to scale the .obj to the game size. Go back to c4d or else, and rescale the .obj (with good uv maps) according to a game base file (by extracting a .nif from the game) and save each part of your project at this size. Then re edit the mod's nif files with these new .obj. Done !!! I have to say that I succeed on a very simple mesh and textures. Some other problems may appear.