Hello,
though I am capable of using nifskope a bit, I am certanly not of using any other 3d-prog. I made a mesh with yacobys cell2nif program. everything is fine except the uv-map is much too small so I see some blurry thingy when I assign a texture. nifskope is able of manipulating uv-maps, but sadly cannot scale them. so may someone be so kind to scale them (attention, the nif is already scaled to twice of the normal landscape size)

http://www.2shared.com/file/11903687/5cad1460/MM_desert.html is the link.

The problem sounds more like the texture is too low-resolution. A full cell mesh is quite large, and Morrowind only supports textures around the 1024/2048 range. When DirectX tries to scale the texture up, it ends up blurring.

You can fix it by splitting the mesh and using multiple textures (not really feasible in NifSkope) or using a detail map as well (more possible, but requires a second set of UV coords).

in the CS, you can apply the same texture repeatedly over the same cell. now, if you export the landscape using yacobys tool, you can only apply this texture one time on the whole cell-mesh. I now thought, with my negligible knowledge of 3d-modelling, that you can scale the uv map so the texture appears multiple times repeated, like in the CS. It is intended to use the same texture (should be some kind of desert mesh)
yeah, splitting the mesh would also be possible (but still not with my modelling experience...)

This is best done in a 3D modelling programme such as http://www.blender.org. Admittedly, I have very little experience using 3D modelling software, but the UV map on your mash is far too big to make editing it with NifSkope easy or efficient.

There are many free UV mapping stand-alone easy to use programs that work with obj format, e.g.
http://www.uvmapper.com/index.html

yeah, Mr. Swiveller, that was my thought, too. so I asked around, if some professional is willing to help

@A1x2e3l: never knew, these programs exist. thanks for suggesting it, worked like a charm.

... well, I've just finished implementing scaling / translation / rotation of UVs in NifSkope - the http://niftools.sourceforge.net/forum/viewtopic.php?f=4&t=2487 has them (as well as some zoom / grid improvements in the UV editor)

that's great news! I was tempted to suggest the implementation of these features in the niftools-forum

edit: tried it out immediately. scaling and rotation works perfectly. the undo-feature is also new, isn't it? may I suggest adding another feature: to flip the UV-map of selected vertices horizontally or vertically.

... I was about to say "scale it by -1" until I realised that I'd set the limits wrong...

Undo/redo has been in the UV editor since 2007.