I need to create some sand dunes to act as a perimeter wall around certain parts of my map. What's the best method to create them so they look realistic?
depends on how much time you have. You could try easygen (google search) but when i tried it, it did not work for me. Patches will work, but if it is too steep the texture gets distorted. I find that a mixture of patches and brushes work well. If it is a very large area that you are thring to make then dont use one patch because it is a b*gger to edit. Use 3x3 or 5x5 then merge them at the end with bobtools extentions, if indeed you merge them at all, it is not nessessary.
Take EasyGen, I take it too, it's easy to make, looks a bit strange, but it's not bad ;)
www.darth-arth.de) - here you can download it and you'll found a tutorial (In german)
Trisoup it, vertex edit it, then apply a shader to it with q3map_nonplanar and q3map_shadeangle in it. For blending, check SplashDamage for alphaMod blending tutorials.
yep,
nothing over alpha_mod blending:D
But do you need it for a dune?
Possibly, to accent some places with a darker texture.